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                             June 27, 2022

       Brian Harris
       Chief Financial Officer
       Summit Materials, Inc.
       1550 Wynkoop Street, 3rd Floor
       Denver, Colorado 80202

                                                        Re: Summit Materials,
Inc.
                                                            Form 10-K for the
Fiscal Year Ended January 1, 2022
                                                            Filed February 24,
2022
                                                            File No. 001-36873

       Dear Mr. Harris:

              We have reviewed your filing and have the following comments. In
some of our
       comments, we may ask you to provide us with information so we may better
understand your
       disclosure.

              Please respond to these comments within ten business days by
providing the requested
       information or advise us as soon as possible when you will respond. If
you do not believe our
       comments apply to your facts and circumstances, please tell us why in
your response.

                                                        After reviewing your
response to these comments, we may have additional comments.

       Form 10-K for the Fiscal Year Ended January 1, 2022 Filed February 24,
2022

       Item 2. Properties, page 33

   1.                                                   We note your disclosure
on page 33 that you do not consider any of your individual
                                                        quarrying operations as
material for disclosure purposes. Please tell us how you assess
                                                        mining property
materiality and how you made this determination. In your response
                                                        please consider Item
1301(c)(3) of Regulation S-K which requires the inclusion of all
                                                        related activities from
exploration through the first point of material external sale,
                                                        including processing,
transportation, and warehousing. Additionally, in your response
                                                        please explain the
materiality of your 2 cement sites, which appears to include 2 of your
                                                        approximately 250 sites
and represents approximately 12% of total sales, 26% of
                                                        operating income, 22%
of adjusted EBITDA, and 20% of total assets.
 Brian Harris
FirstName  LastNameBrian Harris
Summit Materials, Inc.
Comapany
June       NameSummit Materials, Inc.
     27, 2022
June 27,
Page 2 2022 Page 2
FirstName LastName
2.       Please disclose annual production for your properties for each of the
most recently
         completed fiscal years preceding the filing as required by Item
1303(b)(2)(i) of Regulation
         S-K.
3.       For each mineral resource and reserve estimate please disclose the
price, selected by a
         qualified person, which provides a reasonable basis for establishing
the prospects of
         economic extraction as required by Item 1303(b)(3)(iv) of Regulation
S-K.
4.       For each mineral resource and reserve estimate please disclose the
specific point of
         reference selected by a qualified person pursuant to Item
1303(b)(3)(v) of Regulation S-
         K. For example, clarify if resources and reserves are presented
in-situ, prior to
         processing, as saleable products, or other.
        We remind you that the company and its management are responsible for
the accuracy
and adequacy of their disclosures, notwithstanding any review, comments, action
or absence of
action by the staff.

       You may contact John Coleman at 202-551-3610 or Craig Arakawa at
202-551-3650
with questions about comments.



                                                              Sincerely,

                                                              Division of
Corporation Finance
                                                              Office of Energy
& Transportation