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These shares were sold in multiple transactions ranging from $26.67 to $27.18, inclusive. 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These shares were sold in multiple transactions ranging from $28.76 to $29.02, inclusive. 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These shares were sold in multiple transactions ranging from $28.97 to $29.21, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":160602,"source":{"system":"sec-edgar","filing":"0001104659-18-035503","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918035503/a4.xml","form_type":"4"}},{"id":3937112,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"LP Units of Summit Materials Holdings L.P.","published_at":"2018-05-11T18:54:30.000Z","date":"2018-05-10","kind":"exercise","acquired":false,"shares":75000,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F4","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F4","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F4","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."}],"balance_after":517456,"derivative":{"underlying":"Class A Common Stock","underlying_shares":75000},"source":{"system":"sec-edgar","filing":"0001104659-18-032615","document":"a4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918032615/a4.xml","form_type":"4"}},{"id":3937111,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-05-11T18:54:30.000Z","date":"2018-05-10","kind":"exercise","acquired":true,"shares":75000,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F4","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."}],"balance_after":166902,"source":{"system":"sec-edgar","filing":"0001104659-18-032615","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918032615/a4.xml","form_type":"4"}},{"id":3937110,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-05-11T18:54:30.000Z","date":"2018-05-10","kind":"sale","acquired":false,"shares":6200,"price":29.43,"value":182466.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.13 to $29.71, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":91902,"source":{"system":"sec-edgar","filing":"0001104659-18-032615","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918032615/a4.xml","form_type":"4"}},{"id":3937109,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-05-11T18:54:30.000Z","date":"2018-05-09","kind":"sale","acquired":false,"shares":6300,"price":29.64,"value":186732.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.10 to $29.98, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":98102,"source":{"system":"sec-edgar","filing":"0001104659-18-032615","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918032615/a4.xml","form_type":"4"}},{"id":3953636,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-04-30T18:00:47.000Z","date":"2018-04-27","kind":"sale","acquired":false,"shares":6200,"price":28.49,"value":176638.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $28.21 to $28.675, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":104402,"source":{"system":"sec-edgar","filing":"0001104659-18-028709","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918028709/a4.xml","form_type":"4"}},{"id":3953635,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-04-30T18:00:47.000Z","date":"2018-04-26","kind":"sale","acquired":false,"shares":6300,"price":28.62,"value":180306.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $28.44 to $28.855, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":110602,"source":{"system":"sec-edgar","filing":"0001104659-18-028709","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918028709/a4.xml","form_type":"4"}},{"id":3964011,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-04-13T18:01:08.000Z","date":"2018-04-12","kind":"sale","acquired":false,"shares":6200,"price":29.27,"value":181474.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $28.99 to $29.47, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":116902,"source":{"system":"sec-edgar","filing":"0001104659-18-024008","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918024008/a4.xml","form_type":"4"}},{"id":3964010,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-04-13T18:01:08.000Z","date":"2018-04-11","kind":"sale","acquired":false,"shares":6300,"price":29.32,"value":184716.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.07 to $29.49, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":123102,"source":{"system":"sec-edgar","filing":"0001104659-18-024008","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918024008/a4.xml","form_type":"4"}},{"id":3980881,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-28T18:00:37.000Z","date":"2018-03-27","kind":"sale","acquired":false,"shares":6200,"price":30.18,"value":187116.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.97 to $30.38, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":129402,"source":{"system":"sec-edgar","filing":"0001104659-18-021021","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918021021/a4.xml","form_type":"4"}},{"id":3980880,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-28T18:00:37.000Z","date":"2018-03-26","kind":"sale","acquired":false,"shares":6300,"price":30.37,"value":191331.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.14 to $30.66, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":135602,"source":{"system":"sec-edgar","filing":"0001104659-18-021021","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918021021/a4.xml","form_type":"4"}},{"id":3992593,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Options (right to 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ownership guidelines for the Reporting Person, requiring that he hold a value of 6 times his base salary in the Issuer's equity.  After the above reported sales the Reporting Person will hold almost 34 times his base salary in the Issuer's equity (using the closing price of $31.81 on March 13, 2018, the day before the first sale reported).  This calculation does not include unvested options or performance share units."},{"field":"price","element":"transactionPricePerShare","label":"F8","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.70 to $31.68, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":141902,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":12,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992587,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-16","kind":"sale","acquired":false,"shares":5600,"price":30.59,"value":171304.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The Board of Directors of the Issuer has instituted robust ownership guidelines for the Reporting Person, requiring that he hold a value of 6 times his base salary in the Issuer's equity.  After the above reported sales the Reporting Person will hold almost 34 times his base salary in the Issuer's equity (using the closing price of $31.81 on March 13, 2018, the day before the first sale reported).  This calculation does not include unvested options or performance share units."},{"field":"price","element":"transactionPricePerShare","label":"F7","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.50 to $30.68, inclusive. 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After the above reported sales the Reporting Person will hold almost 34 times his base salary in the Issuer's equity (using the closing price of $31.81 on March 13, 2018, the day before the first sale reported).  This calculation does not include unvested options or performance share units."},{"field":"price","element":"transactionPricePerShare","label":"F6","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.25 to $30.38, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":141902,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":9,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992584,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-15","kind":"sale","acquired":false,"shares":7006,"price":31.07,"value":217676.42,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The Board of Directors of the Issuer has instituted robust ownership guidelines for the Reporting Person, requiring that he hold a value of 6 times his base salary in the Issuer's equity.  After the above reported sales the Reporting Person will hold almost 34 times his base salary in the Issuer's equity (using the closing price of $31.81 on March 13, 2018, the day before the first sale reported).  This calculation does not include unvested options or performance share units."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.00 to $31.23, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":196271,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":8,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992583,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-15","kind":"exercise","acquired":true,"shares":61375,"price":18,"value":1104750.0,"ownership":{"direct":true},"balance_after":203277,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":7,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992582,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-14","kind":"sale","acquired":false,"shares":123104,"price":31.01,"value":3817455.04,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The Board of Directors of the Issuer has instituted robust ownership guidelines for the Reporting Person, requiring that he hold a value of 6 times his base salary in the Issuer's equity.  After the above reported sales the Reporting Person will hold almost 34 times his base salary in the Issuer's equity (using the closing price of $31.81 on March 13, 2018, the day before the first sale reported).  This calculation does not include unvested options or performance share units."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.80 to $31.26, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":141902,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":6,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992581,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-14","kind":"sale","acquired":false,"shares":18748,"price":31.6,"value":592436.8,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The Board of Directors of the Issuer has instituted robust ownership guidelines for the Reporting Person, requiring that he hold a value of 6 times his base salary in the Issuer's equity.  After the above reported sales the Reporting Person will hold almost 34 times his base salary in the Issuer's equity (using the closing price of $31.81 on March 13, 2018, the day before the first sale reported).  This calculation does not include unvested options or performance share units."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.50 to $31.98, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":265006,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":5,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992580,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-14","kind":"sale","acquired":false,"shares":300,"price":31.26,"value":9378.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"The Board of Directors of the Issuer has instituted robust ownership guidelines for the Reporting Person, requiring that he hold a value of 6 times his base salary in the Issuer's equity.  After the above reported sales the Reporting Person will hold almost 34 times his base salary in the Issuer's equity (using the closing price of $31.81 on March 13, 2018, the day before the first sale reported).  This calculation does not include unvested options or performance share units."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.25 to $31.28, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":283754,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992579,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-14","kind":"exercise","acquired":true,"shares":47959,"price":17.07,"value":818660.13,"ownership":{"direct":true},"balance_after":284054,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992578,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-14","kind":"exercise","acquired":true,"shares":89850,"price":18,"value":1617300.0,"ownership":{"direct":true},"balance_after":236095,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3992577,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-16T19:22:45.000Z","date":"2018-03-14","kind":"exercise","acquired":true,"shares":4343,"price":18,"value":78174.0,"ownership":{"direct":true},"balance_after":146245,"source":{"system":"sec-edgar","filing":"0001104659-18-018405","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918018405/a4.xml","form_type":"4"}},{"id":3996374,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-14T18:30:44.000Z","date":"2018-03-13","kind":"sale","acquired":false,"shares":6200,"price":32.01,"value":198462.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.76 to $32.27, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":141902,"source":{"system":"sec-edgar","filing":"0001104659-18-017534","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918017534/a4.xml","form_type":"4"}},{"id":3996373,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President & CEO"}}],"security":"Class A Common Stock","published_at":"2018-03-14T18:30:44.000Z","date":"2018-03-12","kind":"sale","acquired":false,"shares":6300,"price":31.73,"value":199899.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.48 to $32.04, inclusive. 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These shares were sold in multiple transactions ranging from $31.77 to $32.51, inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":152846,"source":{"system":"sec-edgar","filing":"0001104659-18-014213","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918014213/a4.xml","form_type":"4"}},{"id":4030403,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Restricted Stock Units","published_at":"2018-02-27T18:06:21.000Z","date":"2018-02-24","kind":"exercise","acquired":false,"shares":14381,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F3","text":"Each restricted stock unit represents a contingent right to receive one share of Class A Common Stock. The restricted stock units settle in either Class A Common Stock or cash (or a combination thereof) at the discretion of the Issuer's compensation committee."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F4","text":"On February 24, 2016, the Reporting Person was granted 43,145 restricted stock units that vest in three equal annual installments beginning on February 24, 2017."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F4","text":"On February 24, 2016, the Reporting Person was granted 43,145 restricted stock units that vest in three equal annual installments beginning on February 24, 2017."}],"balance_after":14382,"derivative":{"underlying":"Class A Common Stock","underlying_shares":14381},"source":{"system":"sec-edgar","filing":"0001104659-18-012917","document":"a4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918012917/a4.xml","form_type":"4"}},{"id":4030402,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-02-27T18:06:21.000Z","date":"2018-02-24","kind":"tax_withholding","acquired":false,"shares":3583,"price":31.74,"value":113724.42,"ownership":{"direct":true},"balance_after":159146,"source":{"system":"sec-edgar","filing":"0001104659-18-012917","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918012917/a4.xml","form_type":"4"}},{"id":4030401,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-02-27T18:06:21.000Z","date":"2018-02-24","kind":"exercise","acquired":true,"shares":14381,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Reflects restricted stock units that upon vesting converted into shares of Class A common stock of the Issuer (\"Class A Common Stock\") on a one-for-one basis."}],"balance_after":162729,"source":{"system":"sec-edgar","filing":"0001104659-18-012917","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918012917/a4.xml","form_type":"4"}},{"id":4066228,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-02-12T18:00:37.000Z","date":"2018-02-09","kind":"sale","acquired":false,"shares":4700,"price":28.52,"value":134044.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $28.05 to $29.04, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":148348,"source":{"system":"sec-edgar","filing":"0001104659-18-008584","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":4,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918008584/a4.xml","form_type":"4"}},{"id":4066227,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-02-12T18:00:37.000Z","date":"2018-02-09","kind":"sale","acquired":false,"shares":1500,"price":27.8,"value":41700.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $27.66 to $27.90, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":153048,"source":{"system":"sec-edgar","filing":"0001104659-18-008584","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918008584/a4.xml","form_type":"4"}},{"id":4066226,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-02-12T18:00:37.000Z","date":"2018-02-08","kind":"sale","acquired":false,"shares":6000,"price":29.39,"value":176340.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $28.92 to $29.82, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":154548,"source":{"system":"sec-edgar","filing":"0001104659-18-008584","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918008584/a4.xml","form_type":"4"}},{"id":4066225,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-02-12T18:00:37.000Z","date":"2018-02-08","kind":"sale","acquired":false,"shares":300,"price":28.66,"value":8598.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $28.62 to $28.71, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":160548,"source":{"system":"sec-edgar","filing":"0001104659-18-008584","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918008584/a4.xml","form_type":"4"}},{"id":4091086,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-01-24T18:00:31.000Z","date":"2018-01-23","kind":"sale","acquired":false,"shares":5800,"price":32.06,"value":185948.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F5","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.585 to $32.54, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":160848,"source":{"system":"sec-edgar","filing":"0001104659-18-003821","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918003821/a4.xml","form_type":"4"}},{"id":4091085,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-01-24T18:00:31.000Z","date":"2018-01-23","kind":"sale","acquired":false,"shares":400,"price":31.43,"value":12572.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.40 to $34.445, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":166648,"source":{"system":"sec-edgar","filing":"0001104659-18-003821","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918003821/a4.xml","form_type":"4"}},{"id":4091084,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-01-24T18:00:31.000Z","date":"2018-01-22","kind":"sale","acquired":false,"shares":6300,"price":31.04,"value":195552.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.82 to $31.51, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F3","text":"Total holdings include shares of Class A common stock of the issuer received pursuant to a stock dividend paid on December 22, 2017."}],"balance_after":167048,"source":{"system":"sec-edgar","filing":"0001104659-18-003821","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918003821/a4.xml","form_type":"4"}},{"id":4100530,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-01-12T18:00:48.000Z","date":"2018-01-11","kind":"sale","acquired":false,"shares":6200,"price":31.45,"value":194990.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.17 to $31.65, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":170610,"source":{"system":"sec-edgar","filing":"0001104659-18-002109","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918002109/a4.xml","form_type":"4"}},{"id":4100529,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2018-01-12T18:00:48.000Z","date":"2018-01-10","kind":"sale","acquired":false,"shares":6300,"price":31.03,"value":195489.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.94 to $31.16, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":176810,"source":{"system":"sec-edgar","filing":"0001104659-18-002109","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465918002109/a4.xml","form_type":"4"}},{"id":4122478,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-12-22T18:01:28.000Z","date":"2017-12-21","kind":"sale","acquired":false,"shares":6200,"price":30.58,"value":189596.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.99 to $30.85, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":183110,"source":{"system":"sec-edgar","filing":"0001104659-17-074903","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917074903/a4.xml","form_type":"4"}},{"id":4122477,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-12-22T18:01:28.000Z","date":"2017-12-20","kind":"sale","acquired":false,"shares":6300,"price":29.93,"value":188559.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.63 to $30.18, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":189310,"source":{"system":"sec-edgar","filing":"0001104659-17-074903","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917074903/a4.xml","form_type":"4"}},{"id":4137976,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-12-08T18:00:56.000Z","date":"2017-12-07","kind":"sale","acquired":false,"shares":6200,"price":30.65,"value":190030.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.19 to $31.425, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":195610,"source":{"system":"sec-edgar","filing":"0001104659-17-072566","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917072566/a4.xml","form_type":"4"}},{"id":4137975,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-12-08T18:00:56.000Z","date":"2017-12-06","kind":"sale","acquired":false,"shares":6300,"price":31.02,"value":195426.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.64 to $31.23, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":201810,"source":{"system":"sec-edgar","filing":"0001104659-17-072566","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917072566/a4.xml","form_type":"4"}},{"id":4151713,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-11-24T18:00:22.000Z","date":"2017-11-22","kind":"sale","acquired":false,"shares":6200,"price":29.86,"value":185132.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.75 to $29.96, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":208110,"source":{"system":"sec-edgar","filing":"0001104659-17-070331","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917070331/a4.xml","form_type":"4"}},{"id":4151712,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-11-24T18:00:22.000Z","date":"2017-11-21","kind":"sale","acquired":false,"shares":6300,"price":29.75,"value":187425.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.56 to $29.90, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":214310,"source":{"system":"sec-edgar","filing":"0001104659-17-070331","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917070331/a4.xml","form_type":"4"}},{"id":4156414,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"LP Units of Summit Materials Holdings L.P.","published_at":"2017-11-20T18:00:44.000Z","date":"2017-11-16","kind":"exercise","acquired":false,"shares":100000,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_price","element":"conversionOrExercisePrice","label":"F1","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."},{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."},{"field":"derivative.exercise_date","element":"exerciseDate","label":"F1","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."},{"field":"derivative.expiration_date","element":"expirationDate","label":"F1","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."}],"balance_after":592456,"derivative":{"underlying":"Class A Common Stock","underlying_shares":100000},"source":{"system":"sec-edgar","filing":"0001104659-17-069675","document":"a4.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":3,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917069675/a4.xml","form_type":"4"}},{"id":4156413,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-11-20T18:00:44.000Z","date":"2017-11-16","kind":"exercise","acquired":true,"shares":100000,"ownership":{"direct":true},"footnotes":[{"field":"price","element":"transactionPricePerShare","label":"F1","text":"Pursuant to the terms of an exchange agreement, dated as of March 11, 2015, the limited partnership units of Summit Materials Holdings L.P. (\"LP Units\") reported herein are exchangeable from and after the first anniversary of the closing of the Issuer's initial public offering (subject to the terms of the exchange agreement and vesting requirements, including certain vesting events more fully described in the Issuer's Registration Statement on Form S-1 (File No. 333-201058)) for shares of the Issuer's Class A common stock on a one-for-one basis."}],"balance_after":220610,"source":{"system":"sec-edgar","filing":"0001104659-17-069675","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917069675/a4.xml","form_type":"4"}},{"id":4165668,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-11-13T18:00:21.000Z","date":"2017-11-09","kind":"sale","acquired":false,"shares":6200,"price":30.33,"value":188046.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.09 to $30.50, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":120610,"source":{"system":"sec-edgar","filing":"0001104659-17-068038","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917068038/a4.xml","form_type":"4"}},{"id":4165667,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-11-13T18:00:21.000Z","date":"2017-11-08","kind":"sale","acquired":false,"shares":6300,"price":30.19,"value":190197.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.87 to $30.58, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":126810,"source":{"system":"sec-edgar","filing":"0001104659-17-068038","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917068038/a4.xml","form_type":"4"}},{"id":4180670,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-10-25T18:00:24.000Z","date":"2017-10-24","kind":"sale","acquired":false,"shares":6200,"price":32.21,"value":199702.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.97 to $32.60, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":133110,"source":{"system":"sec-edgar","filing":"0001104659-17-063773","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917063773/a4.xml","form_type":"4"}},{"id":4180669,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-10-25T18:00:24.000Z","date":"2017-10-23","kind":"sale","acquired":false,"shares":6300,"price":32.04,"value":201852.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.78 to $32.66, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":139310,"source":{"system":"sec-edgar","filing":"0001104659-17-063773","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917063773/a4.xml","form_type":"4"}},{"id":4191071,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-10-05T18:00:58.000Z","date":"2017-10-04","kind":"sale","acquired":false,"shares":6200,"price":32.15,"value":199330.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.78 to $32.315, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":145610,"source":{"system":"sec-edgar","filing":"0001104659-17-061177","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917061177/a4.xml","form_type":"4"}},{"id":4191070,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-10-05T18:00:58.000Z","date":"2017-10-03","kind":"sale","acquired":false,"shares":6300,"price":32.07,"value":202041.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.89 to $32.22, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":151810,"source":{"system":"sec-edgar","filing":"0001104659-17-061177","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917061177/a4.xml","form_type":"4"}},{"id":4202499,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-09-25T18:00:57.000Z","date":"2017-09-22","kind":"sale","acquired":false,"shares":6200,"price":31.61,"value":195982.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F3","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.51 to $31.79, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":158110,"source":{"system":"sec-edgar","filing":"0001104659-17-058685","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917058685/a4.xml","form_type":"4"}},{"id":4202498,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-09-25T18:00:57.000Z","date":"2017-09-21","kind":"sale","acquired":false,"shares":6300,"price":31.51,"value":198513.0,"ownership":{"direct":true},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $31.03 to $31.78, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."}],"balance_after":164310,"source":{"system":"sec-edgar","filing":"0001104659-17-058685","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917058685/a4.xml","form_type":"4"}},{"id":4213634,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-09-08T18:02:00.000Z","date":"2017-09-07","kind":"sale","acquired":false,"shares":6200,"price":30.04,"value":186248.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F4","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.89 to $30.33, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"Reflects securities held by a trust for the benefit of Mr. Hill's family, for which Mr. Hill's spouse serves as trustee."}],"balance_after":360,"source":{"system":"sec-edgar","filing":"0001104659-17-056360","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":2,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917056360/a4.xml","form_type":"4"}},{"id":4213633,"issuer":{"id":16259,"kind":"organization","name":"Summit Materials, Inc.","symbol":"SUM"},"owners":[{"id":45209,"kind":"person","name":"Hill Thomas W.","position":1,"cik":"0001440948","reported_name":"Hill Thomas W.","relationship":{"director":true,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"President and CEO"}}],"security":"Class A Common Stock","published_at":"2017-09-08T18:02:00.000Z","date":"2017-09-06","kind":"sale","acquired":false,"shares":6300,"price":30.27,"value":190701.0,"ownership":{"direct":false,"nature":"See Footnote"},"footnotes":[{"field":"kind","element":"transactionCoding","label":"F1","text":"The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan."},{"field":"price","element":"transactionPricePerShare","label":"F2","text":"The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $30.00 to $30.50, inclusive. The Reporting Person undertakes to provide to the issuer, any security holder of the issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth above."},{"field":"ownership.nature","element":"natureOfOwnership","label":"F3","text":"Reflects securities held by a trust for the benefit of Mr. Hill's family, for which Mr. Hill's spouse serves as trustee."}],"balance_after":6560,"source":{"system":"sec-edgar","filing":"0001104659-17-056360","document":"a4.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1621563/000110465917056360/a4.xml","form_type":"4"}}],"next_cursor":"2017-09-08T18:02:00.000000Z,4213633"}