Exhibit 10.2

EXCHANGE AGREEMENT

EXCHANGE AGREEMENT (this “Agreement”), dated as of March 11, 2015, among Summit
Materials, Inc., a Delaware corporation, Summit Materials Holdings L.P., a
Delaware limited partnership, and the holders of LP Units (as defined herein)
from time to time party hereto.

WHEREAS, the parties hereto desire to provide for the exchange of LP Units for
shares of Class A Common Stock (as defined herein), on the terms and subject to
the conditions set forth herein.

NOW, THEREFORE, in consideration of the mutual covenants and undertakings
contained herein and for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:

ARTICLE I

SECTION 1.1. Definitions

The following definitions shall be for all purposes, unless otherwise clearly
indicated to the contrary, applied to the terms used in this Agreement.

“Agreement” has the meaning set forth in the preamble of this Agreement.

“Class A Common Stock” means the Class A common stock, par value $0.01 per
share, of the Corporation.

“Class B Common Stock” means the Class B common stock, par value $0.01 per
share, of the Corporation.

“Code” means the Internal Revenue Code of 1986, as amended.

“Corporation” means Summit Materials, Inc., a Delaware corporation, and any
successor thereto.

“Exchange” has the meaning set forth in Section 2.1(a) hereof.

“Exchange Rate” means, at any time, the number of shares of Class A Common Stock
for which a LP Unit is entitled to be exchanged at such time. On the date of
this Agreement, the Exchange Rate shall be 1 for 1, subject to adjustment
pursuant to Section 2.2 hereof.

“Financial Sponsor Holders” means the affiliates of The Blackstone Group L.P.
identified as the Financial Sponsor Holders on the signature pages hereto and
Permitted Transferees thereof.

“IPO” has the meaning set forth in Section 2.1(b) hereof.

“LP Unit” means (i) each Class A Unit (as such term is defined in the Summit
Holdings LP Agreement) issued as of the date hereof and (ii) each Class A Unit
or other interest in Summit Holdings that may be issued by Summit Holdings in
the future that is designated by the Corporation as a “LP Unit.”

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“LP Unitholder” means each holder of one or more LP Units that may from time to
time be a party to this Agreement.

“Permitted Transferee” has the meaning given to such term in Section 3.1 hereof.

“Securities Act” has the meaning set forth in Section 2.1(f) hereof.

“Summit Holdings” means Summit Materials Holdings L.P., a Delaware limited
partnership, and any successor thereto.

“Summit Holdco” means Summit Owner Holdco, LLC, a Delaware limited liability
company, and any successor thereto.

“Summit Holdings LP Agreement” means the Fourth Amended and Restated Limited
Partnership Agreement of Summit Holdings, dated on or about the date hereof, as
such agreement may be amended from time to time.

“Unvested Units” has the meaning given to such term in the Summit Holdings LP
Agreement.

ARTICLE II

SECTION 2.1. Exchange of LP Units for Class A Common Stock.

(a) Each Financial Sponsor Holder shall be entitled at any time and from time to
time, upon the terms and subject to the conditions hereof, to surrender LP Units
(other than Unvested Units) to the Corporation, for the account of Summit
Holdings, in exchange for the delivery to the exchanging Financial Sponsor
Holder of a number of shares of Class A Common Stock that is equal to the
product of the number of LP Units surrendered multiplied by the Exchange Rate
(such exchange, an “Exchange”); provided that any such Exchange is for a minimum
of the lesser of 1,000 LP Units or all of the LP Units (other than Unvested
Units) held by such Financial Sponsor Holder.

(b) Each LP Unitholder that is not a Financial Sponsor Holder shall be entitled
from and after the first anniversary of the date of the closing of the initial
public offering and sale of Class A Common Stock (as contemplated by the
Corporation’s Registration Statement on Form S-1 (File No. 333-201058)) (the
“IPO”), or, if later, the date of the initial filing by the Corporation of a
registration statement with the U.S. Securities and Exchange Commission to cover
delivery of shares of Class A Common Stock to LP Unitholders upon an Exchange
(as defined herein) of LP Units (other than Unvested Units), at any time and
from time to time, upon the terms and subject to the conditions hereof to elect
to effect an Exchange; provided that any such Exchange is for a minimum of the
lesser of 1,000 LP Units or all of the LP Units (other than Unvested Units) held
by such LP Unitholder.

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(c) An LP Unitholder shall exercise its right to exchange LP Units as set forth
in Section 2.1(a) or Section 2.1(b) hereof, as applicable, by delivering to the
Corporation and to Summit Holdings a written election of exchange in respect of
the LP Units to be exchanged substantially in the form of Exhibit A hereto and
any certificates, if any, representing LP Units, duly executed by such holder or
such holder’s duly authorized attorney, in each case delivered during normal
business hours at the principal executive offices of the Corporation and of
Summit Holdings. As promptly as practicable following the delivery of such a
written election of exchange, Summit Holdings shall deliver or cause to be
delivered at the offices of the then-acting registrar and transfer agent of the
Class A Common Stock or, if there is no then-acting registrar and transfer agent
of the Class A Common Stock, at the principal executive offices of the
Corporation, the number of shares of Class A Common Stock deliverable upon such
Exchange, registered in the name of the relevant exchanging LP Unitholder. To
the extent the Class A Common Stock is settled through the facilities of The
Depository Trust Company, and the exchanging LP Unitholder is permitted to hold
shares of Class A Common Stock through The Depository Trust Company, Summit
Holdings will, subject to Section 2.1(d) hereof, upon the written instruction of
an exchanging LP Unitholder, use its reasonable best efforts to deliver or cause
to be delivered the shares of Class A Common Stock deliverable to such
exchanging LP Unitholder, through the facilities of The Depository Trust
Company, to the account of the participant of The Depository Trust Company
designated by such exchanging LP Unitholder. The Corporation shall take such
actions as may be required to ensure the performance by Summit Holdings of its
obligations under this Section 2.1(c) and Section 2.1(a) and Section 2.1(b)
hereof, including the issuance and sale of shares of Class A Common Stock to or
for the account of Summit Holdings in exchange for the delivery to the
Corporation of a number of LP Units that is equal to the number of LP Units
surrendered by an exchanging LP Unitholder. Any LP Unitholder (other than Summit
Holdco) that surrenders all of its LP Units (other than Unvested Units) held by
such LP Unitholder to the Corporation, for the account of Summit Holdings,
pursuant to this Section 2.1 shall concurrently surrender all shares of Class B
Common Stock held by such LP Unitholder (including any fractions thereof) to the
Corporation.

(d) Summit Holdings and each exchanging LP Unitholder shall bear its own
expenses in connection with the consummation of any Exchange, whether or not any
such Exchange is ultimately consummated, except that Summit Holdings shall bear
any transfer taxes, stamp taxes or duties, or other similar taxes in connection
with, or arising by reason of, any Exchange; provided, however, that if any
shares of Class A Common Stock are to be delivered in a name other than that of
the LP Unitholder that requested the Exchange, then such LP Unitholder and/or
the person in whose name such shares are to be delivered shall pay to Summit
Holdings the amount of any transfer taxes, stamp taxes or duties, or other
similar taxes in connection with, or arising by reason of, such Exchange or
shall establish to the reasonable satisfaction of Summit Holdings that such tax
has been paid or is not payable.

(e) To the extent the Corporation or Summit Holdings shall determine that LP
Units do not meet the requirements of Treasury Regulation Section 1.7704-1(h),
the Corporation or Summit Holdings may impose such restrictions on Exchange as
the Corporation or Summit Holdings may reasonably determine to be necessary or
advisable so that Summit Holdings is not treated as a “publicly traded
partnership” under Section 7704 of the Code; provided, that each LP Unitholder
shall be entitled at any time Exchange LP Units for Class A Common Stock,
provided that the aggregate number of LP Units surrendered by such LP Unitholder
in any such Exchange

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is greater than 2% of the then-outstanding LP Units (provided that such Exchange
constitutes part of a “block transfer” within the meaning of Treasury Regulation
Section 1.7704-1(e)(2)). Notwithstanding anything to the contrary herein, no
Exchange shall be permitted (and, if attempted, shall be void ab initio) if, in
the good faith determination of the Corporation or of Summit Holdings, such an
Exchange would pose a material risk that Summit Holdings would be a “publicly
traded partnership” under Section 7704 of the Code.

(f) For the avoidance of doubt, and notwithstanding anything to the contrary
herein, an LP Unitholder shall not be entitled to exchange LP Units to the
extent the Corporation determines that such Exchange (i) would be prohibited by
law or regulation (including, without limitation, the unavailability of any
requisite registration statement filed under the U.S. Securities Act of 1933, as
amended (the “Securities Act”), or any exemption from the registration
requirements thereunder) or (ii) would not be permitted under any other
agreements with the Corporation or its subsidiaries to which such LP Unitholder
may be party (including, without limitation, the Summit Holdings LP Agreement)
or any written policies of the Corporation related to unlawful or inappropriate
trading applicable to its directors, officers or other personnel.

(g) The Corporation may adopt reasonable procedures for the implementation of
the exchange provisions set forth in this Article II, including, without
limitation, procedures for the giving of notice of an election of exchange.

SECTION 2.2. Adjustment.

(a) The Exchange Rate shall be adjusted accordingly if there is: (a) any
subdivision (by any unit split, unit distribution, reclassification,
reorganization, recapitalization or otherwise) or combination (by reverse unit
split, reclassification, reorganization, recapitalization or otherwise) of the
LP Units that is not accompanied by an identical subdivision or combination of
the Class A Common Stock; or (b) any subdivision (by any stock split, stock
dividend or distribution, reclassification, reorganization, recapitalization or
otherwise) or combination (by reverse stock split, reclassification,
reorganization, recapitalization or otherwise) of the Class A Common Stock that
is not accompanied by an identical subdivision or combination of the LP Units;
provided, however, no adjustment to the Exchange Rate will be made solely as a
result of a stock dividend by the Corporation that is effected in order to
maintain the relationship between the shares of Class A Common Stock and LP
Units . If there is any reclassification, reorganization, recapitalization or
other similar transaction in which the Class A Common Stock is converted or
changed into another security, securities or other property, then upon any
subsequent Exchange, an exchanging LP Unitholder shall be entitled to receive
the amount of such security, securities or other property that such exchanging
LP Unitholder would have received if such Exchange had occurred immediately
prior to the effective date of such reclassification, reorganization,
recapitalization or other similar transaction, taking into account any
adjustment as a result of any subdivision (by any split, distribution or
dividend, reclassification, reorganization, recapitalization or otherwise) or
combination (by reverse split, reclassification, recapitalization or otherwise)
of such security, securities or other property that occurs after the effective
time of such reclassification, reorganization, recapitalization or other similar
transaction. Except as may be required in the immediately preceding sentence, no
adjustments in respect of distributions shall be made upon the exchange of any
LP Unit.

SECTION 2.3. Class A Common Stock to be Issued.

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(a) The Corporation shall at all times reserve and keep available out of its
authorized but unissued Class A Common Stock, solely for the purpose of issuance
upon an Exchange, such number of shares of Class A Common Stock as shall be
deliverable upon any such Exchange; provided that nothing contained herein shall
be construed to preclude Summit Holdings from satisfying its obligations in
respect of the Exchange of the LP Units by delivery of shares of Class A Common
Stock which are held in the treasury of the Corporation or are held by Summit
Holdings or any of their subsidiaries or by delivery of purchased shares of
Class A Common Stock (which may or may not be held in the treasury of the
Corporation or held by any subsidiary thereof). The Corporation and Summit
Holdings covenant that all Class A Common Stock issued upon an Exchange will,
upon issuance, be validly issued, fully paid and non-assessable.

(b) The Corporation and Summit Holdings covenant and agree that, to the extent
that a registration statement under the Securities Act is effective and
available for shares of Class A Common Stock to be delivered with respect to any
Exchange, shares that have been registered under the Securities Act shall be
delivered in respect of such Exchange. In the event that any Exchange in
accordance with this Agreement is to be effected at a time when any required
registration has not become effective or otherwise is unavailable, upon the
request and with the reasonable cooperation of the LP Unitholder requesting such
Exchange, the Corporation and Summit Holdings shall use commercially reasonable
efforts to promptly facilitate such Exchange pursuant to any reasonably
available exemption from such registration requirements. The Corporation and
Summit Holdings shall use commercially reasonable efforts to list the Class A
Common Stock required to be delivered upon exchange prior to such delivery upon
each national securities exchange or inter-dealer quotation system upon which
the outstanding Class A Common Stock may be listed or traded at the time of such
delivery.

SECTION 2.4. Restrictions. Any restrictions on transfer under any agreements
with the Corporation or any of its subsidiaries to which an exchanging LP
Unitholder may be party shall apply, mutatis mutandis, to any shares of Class A
Common Stock.

ARTICLE III

SECTION 3.1. Additional LP Unitholders. To the extent an LP Unitholder validly
transfers any or all of such holder’s LP Units to another person in a
transaction in accordance with, and not in contravention of, the Summit Holdings
LP Agreement or any other agreement or agreements with the Corporation or any of
its subsidiaries to which a transferring LP Unitholder may be party, then such
transferee (each, a “Permitted Transferee”) shall have the right to execute and
deliver a joinder to this Agreement, substantially in the form of Exhibit B
hereto, whereupon such Permitted Transferee shall become an LP Unitholder
hereunder. To the extent Summit Holdings issues LP Units in the future, Summit
Holdings shall be entitled, in its sole discretion, to make any holder of such
LP Units an LP Unitholder hereunder through such holder’s execution and delivery
of a joinder to this Agreement, substantially in the form of Exhibit B hereto.

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SECTION 3.2. Addresses and Notices. All notices, requests, claims, demands and
other communications hereunder shall be in writing and shall be given (and shall
be deemed to have been duly given upon receipt) by delivery in person, by
courier service, by fax, by electronic mail (delivery receipt requested) or by
registered or certified mail (postage prepaid, return receipt requested) to the
respective parties at the following addresses (or at such other address for a
party as shall be as specified in a notice given in accordance with this
Section 3.2):

(a) If to the Corporation, to:

Summit Materials, Inc.

1550 Wynkoop, 3rd Floor

Denver, Colorado 80202

Attention: Chief Legal Officer

Fax: (303) 893-6993

Email: Legal@Summit-Materials.com

(b) If to Summit Holdings, to:

Summit Materials Holdings L.P.

c/o Summit Materials, Inc.

1550 Wynkoop, 3rd Floor

Denver, Colorado 80202

Attention: Chief Legal Officer

Fax: (303) 893-6993

Email: Legal@Summit-Materials.com

(c) If to any LP Unitholder, to the address and other contact information set
forth in the records of Summit Holdings from time to time.

SECTION 3.3. Further Action. The parties shall execute and deliver all
documents, provide all information and take or refrain from taking action as may
be necessary or appropriate to achieve the purposes of this Agreement.

SECTION 3.4. Binding Effect. This Agreement shall be binding upon and inure to
the benefit of all of the parties and, to the extent permitted by this
Agreement, their successors, executors, administrators, heirs, legal
representatives and assigns.

SECTION 3.5. Severability. If any term or other provision of this Agreement is
held to be invalid, illegal or incapable of being enforced by any rule of law,
or public policy, all other conditions and provisions of this Agreement shall
nevertheless remain in full force and effect so long as the economic or legal
substance of the transactions is not affected in any manner materially adverse
to any party. Upon a determination that any term or other provision is invalid,
illegal or incapable of being enforced, the parties hereto shall negotiate in
good faith to modify this Agreement so as to effect the original intent of the
parties as closely as possible in a mutually acceptable manner in order that the
transactions contemplated hereby be consummated as originally contemplated to
the fullest extent possible.

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SECTION 3.6. Amendment. The provisions of this Agreement may be amended only by
the affirmative vote or written consent of each of (i) the Corporation,
(ii) Summit Holdings, (iii) LP Unitholders holding a majority of the then
outstanding LP Units (excluding LP Units held by the Corporation) and (iv) for
so long as the Financial Sponsor Holders collectively own, in the aggregate, at
least 5% of the outstanding LP Units, each of the Financial Sponsor Holders.

SECTION 3.7. Waiver. No failure by any party to insist upon the strict
performance of any covenant, duty, agreement or condition of this Agreement or
to exercise any right or remedy consequent upon a breach thereof shall
constitute waiver of any such breach of any other covenant, duty, agreement or
condition.

SECTION 3.8. Submission to Jurisdiction; Waiver of Jury Trial.

(a) Any and all disputes which cannot be settled amicably, including any
ancillary claims of any party, arising out of, relating to or in connection with
the validity, negotiation, execution, interpretation, performance or
non-performance of this Agreement (including the validity, scope and
enforceability of this arbitration provision) shall be finally settled by
arbitration conducted by a single arbitrator in New York in accordance with the
then-existing Rules of Arbitration of the International Chamber of Commerce. If
the parties to the dispute fail to agree on the selection of an arbitrator
within thirty (30) days of the receipt of the request for arbitration, the
International Chamber of Commerce shall make the appointment. The arbitrator
shall be a lawyer and shall conduct the proceedings in the English language.
Performance under this Agreement shall continue if reasonably possible during
any arbitration proceedings.

(b) Notwithstanding the provisions of Section 3.8 (a), the parties hereto may
bring an action or special proceeding in any court of competent jurisdiction for
the purpose of compelling a party to arbitrate, seeking temporary or preliminary
relief in aid of an arbitration hereunder, and/or enforcing an arbitration award
and, for the purposes of this Section 3.8(b), each party hereto (i) expressly
consents to the application of Section 3.8 (c) to any such action or proceeding
and (ii) agrees that proof shall not be required that monetary damages for
breach of the provisions of this Agreement would be difficult to calculate and
that remedies at law would be inadequate.

(c)(i) EACH PARTY HERETO IRREVOCABLY SUBMITS TO THE JURISDICTION OF COURTS
LOCATED IN NEW YORK, NEW YORK FOR THE PURPOSE OF ANY JUDICIAL PROCEEDING BROUGHT
IN ACCORDANCE WITH THE PROVISIONS OF THIS SECTION 3.8, OR ANY JUDICIAL
PROCEEDING ANCILLARY TO AN ARBITRATION OR CONTEMPLATED ARBITRATION ARISING OUT
OF OR RELATING TO OR CONCERNING THIS AGREEMENT. Such ancillary judicial
proceedings include any suit, action or proceeding to compel arbitration, to
obtain temporary or preliminary judicial relief in aid of arbitration, or to
confirm an arbitration award. The parties acknowledge that the fora designated
by this Section 3.8(c) have a reasonable relation to this Agreement and to the
parties’ relationship with one another.

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(ii) The parties hereby waive, to the fullest extent permitted by applicable
law, any objection which they now or hereafter may have to personal jurisdiction
or to the laying of venue of any such ancillary suit, action or proceeding
brought in any court referred to in this Section 3.8(c), and such parties agree
not to plead or claim the same.

SECTION 3.9. Counterparts. This Agreement may be executed and delivered
(including by facsimile transmission or by e-mail delivery of a “.pdf” format
data file) in one or more counterparts, and by the different parties hereto in
separate counterparts, each of which when executed and delivered shall be deemed
to be an original but all of which taken together shall constitute one and the
same agreement. Copies of executed counterparts transmitted by telecopy, by
e-mail delivery of a “.pdf” format data file or other electronic transmission
service shall be considered original executed counterparts for purposes of this
Section 3.9.

SECTION 3.10. Tax Treatment. Solely for U.S. federal income tax purposes, this
Agreement shall be treated as part of the partnership agreement of Summit
Holdings as described in Section 761(c) of the Code and
Sections 1.704-1(b)(2)(ii)(h) and 1.761-1(c) of the Treasury Regulations
promulgated thereunder. As required by the Code and the Treasury Regulations,
the parties shall report any Exchange consummated hereunder as a taxable sale of
the LP Units by an LP Unitholder to the Corporation, and no party shall take a
contrary position on any income tax return, amendment thereof or communication
with a taxing authority unless an alternate position is permitted under the Code
and Treasury Regulations and the Corporation consents in writing.

SECTION 3.11. Specific Performance. The parties hereto agree that irreparable
damage would occur in the event that any of the provisions of this Agreement
were not performed in accordance with its specific terms or were otherwise
breached. It is accordingly agreed that the parties shall be entitled to
specific performance of the terms and provisions hereof, in addition to any
other remedy to which they are entitled at law or in equity.

SECTION 3.12. Independent Nature of LP Unitholders’ Rights and Obligations. The
obligations of each LP Unitholder hereunder are several and not joint with the
obligations of any other LP Unitholder, and no LP Unitholder shall be
responsible in any way for the performance of the obligations of any other LP
Unitholder hereunder. The decision of each LP Unitholder to enter into to this
Agreement has been made by such LP Unitholder independently of any other LP
Unitholder. Nothing contained herein, and no action taken by any LP Unitholder
pursuant hereto, shall be deemed to constitute the LP Unitholders as a
partnership, an association, a joint venture or any other kind of entity, or
create a presumption that the LP Unitholders are in any way acting in concert or
as a group with respect to such obligations or the transactions contemplated
hereby. The Corporation acknowledges that the LP Unitholders are not acting in
concert or as a group, and the Corporation will not assert any such claim with
respect to such obligations or the transactions contemplated hereby.

SECTION 3.13. Applicable Law. This Agreement shall be governed by, and construed
in accordance with, the law of the State of Delaware.

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[Remainder of Page Intentionally Left Blank]

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IN WITNESS WHEREOF, the parties have caused this Agreement to be duly executed
and delivered, all as of the date first set forth above.

 

Corporation: SUMMIT MATERIALS, INC. By: /s/ Thomas W. Hill Name: Thomas W. Hill
Title: Chief Executive Officer

 

Summit Holdings: SUMMIT MATERIALS HOLDINGS L.P. By: /s/ Thomas W. Hill Name:
Thomas W. Hill Title: Chief Executive Officer Financial Sponsor Holders:
BLACKSTONE PARTICIPATION PARTNERSHIP (CAYMAN) V-NQ L.P. By: BCP V-NQ GP L.L.C.,
its U.S. general partner By:

/s/ Neil P. Simpkins

Name: Neil P. Simpkins Title: Senior Managing Director BLACKSTONE FAMILY
INVESTMENT PARTNERSHIP (CAYMAN) V-NQ L.P. By: BCP V-NQ GP L.L.C., its U.S.
general partner By:

/s/ Neil P. Simpkins

Name: Neil P. Simpkins Title: Senior Managing Director

[Signature Page – Exchange Agreement]

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BLACKSTONE CAPITAL PARTNERS (CAYMAN) V- NQ L.P. By: Blackstone Management
Associates (Cayman) V-NQ L.P., its general partner By: BCP V-NQ GP L.L.C., its
U.S. general partner By:

/s/ Neil P. Simpkins

Name: Neil P. Simpkins Title: Senior Managing Director BLACKSTONE CAPITAL
PARTNERS (CAYMAN) NQ V-AC L.P. By: Blackstone Management Associates (Cayman)
V-NQ L.P., its general partner By: BCP V-NQ GP L.L.C., its U.S. general partner
By:

/s/ Neil P. Simpkins

Name: Neil P. Simpkins Title: Senior Managing Director

[Signature Page – Exchange Agreement]

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SUMMIT BCP INTERMEDIATE HOLDINGS L.P. By: Summit BCP Intermediate Holdings GP,
Ltd., its general partner By:

/s/ Neil P. Simpkins

Name: Neil P. Simpkins Title: Director

[Signature Page – Exchange Agreement]

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Other LP Unitholders: All other LP Unitholders listed in Annex 1 attached hereto
By:

/s/ Anne Lee Benedict

Name: Anne Lee Benedict Title: Attorney-in-Fact

[Signature Page – Exchange Agreement]

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ANNEX 1

Thomas W. Hill

Jane B. Hill, Trustee for The Hill Trust

Silverhawk Summit, L.P.

Gardner Family Investments, LLC

Charles Goodyear

Summit Materials Holding-G, L.L.C.

Michael J. Brady

Robert Price

Anthony Keenan

Anya Fonina Civitella

Damian J. Murphy

Angela Dziubek

R. Michael Johnson

Thomas A. Beck

M. Shane Evans

Val Staker

Filip Wojcikowski

Lane Bybee

Douglas C. Rauh

Clint Pulley

John R. Murphy

Margaret Harris, Trustee of the Harris Family 2014 Trust

Kevin A. Gill

Jennifer Rose

Brienne Wode

Valerie Barker

Shannon Neeley

Ashley Sakwa

Anne Lee Benedict

Howard L. Lance

Hinkle Family Assets Holding Company, LLC

RMD Investment Group, L.L.C.

K Six, LLC

John Ramming

Lance Townsend

William B. Carroll

Grant D. Shelton

Dean K. Lundquist

James D. Ramming

David L. Fuller

Clyde C. Fuller

D’arcy Todd Barten

Perry Glen Shepard

Robert K. Hall

Mark Buster

Bryan Kalbfleisch

Larry Winkleman

Amanda Mohr

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EXHIBIT A

[FORM OF]

ELECTION OF EXCHANGE

Summit Materials, Inc.

1550 Wynkoop, 3rd Floor

Denver, Colorado 80202

Attention: Chief Legal Officer

Summit Materials Holdings L.P.

c/o Summit Materials, Inc.

1550 Wynkoop, 3rd Floor

Denver, Colorado 80202

Attention: Chief Legal Officer

Reference is hereby made to the Exchange Agreement, dated as of March 11, 2015
(the “Exchange Agreement”), among Summit Materials, Inc., a Delaware
corporation, Summit Materials Holdings L.P., a Delaware limited partnership, and
the holders of LP Units from time to time party thereto. Capitalized terms used
but not defined herein shall have the meanings given to them in the Exchange
Agreement.

The undersigned LP Unitholder hereby transfers to the Corporation, for the
account of Summit Holdings, the number of LP Units set forth below in exchange
for shares of Class A Common Stock to be issued in its name as set forth below,
as set forth in the Exchange Agreement.

Legal Name of LP Unitholder:            
                                                                   

Address:                                                             
                                                                   

Number of LP Units to be exchanged:         
                                              

The undersigned hereby represents and warrants that (i) the undersigned has full
legal capacity to execute and deliver this Election of Exchange and to perform
the undersigned’s obligations hereunder; (ii) this Election of Exchange has been
duly executed and delivered by the undersigned and is the legal, valid and
binding obligation of the undersigned enforceable against it in accordance with
the terms thereof or hereof, as the case may be, subject to applicable
bankruptcy, insolvency and similar laws affecting creditors’ rights generally
and the availability of equitable remedies; (iii) the LP Units subject to this
Election of Exchange are being transferred to the Corporation free and clear of
any pledge, lien, security interest, encumbrance, equities or claim; and (iv) no
consent, approval, authorization, order, registration or qualification of any
third party or with any court or governmental agency or body having jurisdiction
over the undersigned or the LP Units subject to this Election of Exchange is
required to be obtained by the undersigned for the transfer of such LP Units to
the Corporation.

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The undersigned hereby irrevocably constitutes and appoints any officer of the
Corporation or of Summit Holdings as the attorney of the undersigned, with full
power of substitution and resubstitution in the premises, to do any and all
things and to take any and all actions that may be necessary to transfer to the
Corporation, for the account of Summit Holdings, the LP Units subject to this
Election of Exchange and to deliver to the undersigned the shares of Class A
Common Stock to be delivered in exchange therefor.

IN WITNESS WHEREOF the undersigned, by authority duly given, has caused this
Election of Exchange to be executed and delivered by the undersigned or by its
duly authorized attorney.

 

 

Name:  

      Dated:  

 

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EXHIBIT B

[FORM OF]

JOINDER AGREEMENT

This Joinder Agreement (“Joinder Agreement”) is a joinder to the Exchange
Agreement, dated as of March 11, 2015 (the “Exchange Agreement”), among Summit
Materials, Inc., a Delaware corporation (the “Corporation”), Summit Materials
Holdings L.P., a Delaware limited partnership (“Summit Holdings”), and each of
the LP Unitholders from time to time party thereto. Capitalized terms used but
not defined in this Joinder Agreement shall have their meanings given to them in
the Exchange Agreement. This Joinder Agreement shall be governed by, and
construed in accordance with, the law of the State of Delaware. In the event of
any conflict between this Joinder Agreement and the Exchange Agreement, the
terms of this Joinder Agreement shall control.

The undersigned hereby joins and enters into the Exchange Agreement having
acquired LP Units in Summit Holdings. By signing and returning this Joinder
Agreement to the Corporation, the undersigned accepts and agrees to be bound by
and subject to all of the terms and conditions of and agreements of an LP
Unitholder contained in the Exchange Agreement, with all attendant rights,
duties and obligations of an LP Unitholder thereunder. The parties to the
Exchange Agreement shall treat the execution and delivery hereof by the
undersigned as the execution and delivery of the Exchange Agreement by the
undersigned and, upon receipt of this Joinder Agreement by the Corporation and
by Summit Holdings, the signature of the undersigned set forth below shall
constitute a counterpart signature to the signature page of the Exchange
Agreement.

 

Name:                                                                       
Address for Notices: With copies to:

 

 

 

 

 

 

Attention: