2016 Credit Suisse Homebuilders and Building Products Conference

Safe Harbor and Basis of Presentation Forward-Looking Statement Safe Harbor - This presentation includes "forward-looking statements" within the meaning of the Private Securities Litigation Reform Act of 1995. All of these forward-looking statements are based on estimates and assumptions made by our management that, although believed by us to be reasonable, are inherently uncertain. Forward-looking statements involve risks and uncertainties, including, but not limited to, economic, competitive, governmental and technological factors outside of our control that may cause our business, strategy or actual results to differ materially from the forward-looking statements. In addition, these risks and uncertainties may include, among other things: changes in the prices, supply, and/or demand for products which we distribute; general economic and business conditions in the United States; the activities of competitors; changes in significant operating expenses; changes in the availability of capital and interest rates; adverse weather patterns or conditions; acts of cyber intrusion; variations in the performance of the financial markets, including the credit markets; and other factors described in the "Risk Factors" section in our Annual Report on Form 10-K for the fiscal year ended April 30, 2016, and in our other periodic reports filed with the SEC. In addition, the statements in this presentation are made as of August 9, 2016. We undertake no obligation to update any of the forward looking statements made herein, whether as a result of new information, future events, changes in expectation or otherwise. These forward-looking statements should not be relied upon as representing our views as of any date subsequent to August 9, 2016. Use of Non-GAAP and Adjusted Financial Information - To supplement GAAP financial information, we use adjusted measures of operating results which are non-GAAP measures. This non-GAAP adjusted financial information is provided as additional information for investors. These adjusted results exclude certain costs, expenses, gains and losses, and we believe their exclusion can enhance an overall understanding of our past financial performance and also our prospects for the future. These adjustments to our GAAP results are made with the intent of providing both management and investors a more complete understanding of our operating performance by excluding non-recurring, infrequent or other non-cash charges that are not believed to be material to the ongoing performance of our business. The presentation of this additional information is not meant to be considered in isolation or as a substitute for GAAP measures of net earnings, diluted earnings per share or net cash provided by (used in) operating activities prepared in accordance with generally accepted accounting principles in the United States. 2

GMS at a Glance GMS Overview Net Sales Breakdown (FY 2016) #1 North American specialty distributor of interior construction products (1) 13% market share in wallboard 14% market share in ceilings Critical link between suppliers and highly fragmented customer base 20,000+ interior contractor customers National scale with 190 branches across 41 states and the District of Columbia Broad product offering of 20,000+ SKUs enabling GMS to be a one-stop-shop for the interior contractor Substantial diversification across customers, geographies and end markets Balanced mix of commercial and residential construction as well as new construction and R&R Wallboard $871mm 47% Ceilings $297mm 16% Steel Framing $281mm 15% Other $409mm 22% ($ in millions, April FYE) 5-yr CAGR: 16.1% 5-yr CAGR: 50.8% (2) % Margin 2.0% 3.3% 5.0% 6.4% 6.7% 7.4% % Growth NA 12% 17% 16% 16% 18% Adjusted EBITDA (2) Net Sales (1) Net sales do not reflect net sales attributable to acquired entities for any period prior to their respective dates of acquisition. FY 2015 and FY 2016 Adj. EBITDA includes approximately $8.1 million and $12.1 million, respectively, from entities acquired in FY 2015 and FY 2016, respectively, for the period prior to their respective dates of acquisition. However, Adj. EBITDA margin and the 5-year CAGR exclude the impact of the entities acquired for the period prior to their respective dates of acquisition. For a reconciliation of Adj. EBITDA to Net Income (loss), the most directly comparable GAAP metric, see Appendix. 3 Residential ~40% Commercial ~60% $106 $138 $8 $12 $18 $32 $58 $87 $114 $150 FY-11 FY-12 FY-13 FY-14 FY-15 FY-16 $881 $991 $1,162 $1,353 $1,570 $1,858 FY-11 FY-12 FY-13 FY-14 FY-15 FY-16

GMS has an integrated national platform, but operates through over 40 local brands that are highly regarded in their markets Branch managers are empowered and incented to run operations like entrepreneurs within parameters of the overall business model GMS’s model ensures customer and product decisions are made by the individual with the best local market knowledge GMS’s model generates significant economies of scale, while maintaining the high service levels, entrepreneurial culture, and the customer intimacy of a local business National Platform With Local Presence And Independent Brands GMS combines the benefits of national scale with a local “go-to-market” strategy Representative Local Brands 4

Product Overview #1 Market Position Used to finish the interior walls and ceilings in residential, commercial and institutional construction projects Exterior wallboard Description Wallboard Ceilings Steel Framing Other Products #1 Market Position Suspended ceiling systems primarily comprised of mineral fiber, ceiling tile and grid Architectural specialty ceilings systems Steel framing products for interior walls Sold into commercial applications, typically as part of a package with wallboard, ceilings and other products Primarily consists of complementary interior construction products, including joint compound, finishing materials, tools and fasteners, safety products and EIFS (exterior insulation and finishing system) Various types of wallboard including: 1/2 inch standard (residential), 5/8 inch fire rated (commercial), foil backed, lead lined, moisture resistant, mold resistant and vinyl covered Products Acoustical ceiling tiles (standard and architectural specialty) Clips Covered fiberglass Ceiling tile grid Hangers Drywall steel Flat stock Plastering steel Structural framing Studs and track Adhesives EIFS Insulation Joint compound and plaster Safety equipment Tools and fasteners 5

A One-Stop-Shop for the Interior Contractor “One-stop-shop” for the Interior Contractor Interior Contractor Wallboard Steel Framing Joint Compound Tools Safety Products Insulation GMS sells a complementary and complete product offering to the interior contractor who installs wallboard, ceilings, steel framing and all the ancillary products needed to complete the job Wallboard Ceilings Key manufacturers Specialty Distributors (~65%) Lumberyards (~15%) Big Box Retailers (~20%) Specialty Distributors (~90%) Other (~10%) Channel (1) Ceilings Fasteners (1) Based on management estimates. Highlighted box indicates channels in which GMS competes. GMS Serves as a Critical Link Between Suppliers and a Highly Fragmented Customer Base Specialty wallboard distributors lead the wallboard distribution channel with ~65% Specialty distributors account for ~90% of ceilings distribution channel 6

Highly Attractive Industry Structure Source: Management estimates. Based on 2015 financials. Based on USG Corporation’s public filings and our management estimates. Number of North American suppliers declined from 12 in late 1990s to 7 today The top 4 represent ~76% of the market (1) Highly consolidated supplier base Average price increase of ~4% annually since 2007 (2) GMS maintains a strong, long-standing relationship with the supplier of the leading ceiling tile brand, with exclusivity in many of GMS’s markets Ceilings Wallboard Top 3 represent ~95% Consolidated supplier base focused on price and margin optimization 7

Leading Specialty Distributor Poised for Continued Growth Market Leader with Significant Scale Advantages – #1 North American Distributor of Wallboard and Ceilings Differentiated Service Model Drives Market Leadership Multiple Levers to Drive Above-Market Growth – Market Share, Greenfields, M&A, Operating Leverage Capitalizing on Large, Diverse End Markets Poised for Continued Growth Entrepreneurial Culture with Dedicated Employees and Experienced Leadership Driving Superior Execution 8

#1 position in wallboard and ceilings with 13% and 14% market share, respectively National scale and leading market positions drive: Purchasing advantage over smaller competitors Access to market leading ceilings (with exclusivity in many markets) and wallboard brands Ability to sell to large homebuilders and commercial contractors on a national basis (1) Source: Gypsum Association and GMS data. Market Leader with Scale Advantages Virtuous Cycle Creates Defensible Market Position National Scale Combined With Local Expertise Greater Product Availability & Resources for Investment Differentiated Service Model Advantageous Purchasing Market Share Gains #1 Market Position GMS’s scale creates sustainable competitive advantages that are expected to reinforce its market position and lead to further market share gains GMS Branch Locations 9

Differentiated Service Model Drives Market Leadership Delivery Execution Safety Customer Support Product Availability Breadth of Product Availability Differentiates GMS from Smaller Competitors Ensures product availability Access to latest product innovations; significant customer for its top suppliers Leading ceiling tile line with exclusivity in certain markets Approximately 600 Salespeople Helping Customers Succeed in the Market Place Deep technical expertise and knowledge of local markets Key intermediary for suppliers in reaching the end customer Provides business development, bid support, expertise, and sourcing Differentiated Service Model Logistics Execution is Critical Given Weight And Delivery Requirements Reputation for best-in-class delivery execution Strong processes, sequenced loading, coordinated delivery, and leading technology and equipment Customized delivery plan and unique degree of quality control Network of Regional Safety Managers Strict and consistent safety procedures Safety protocol critical to larger commercial contractor customers Superior Safety Track Record is Highly Valued by Customers GMS believes it sets the industry standard in product availability, customer support, delivery execution and safety; this differentiated service model has driven attractive gross profit margins 10

Multiple Levers to Drive Growth End Market Recovery and Expansion Market Growth Operating Leverage Operational Excellence Margin Expansion Organic Growth Strategic Acquisitions ($ in millions, April FYE) 5-yr CAGR: 16.1% 5-yr CAGR: 50.8% (2) % Margin 2.0% 3.3% 5.0% 6.4% 6.7% 7.4% % Growth NA 12% 17% 16% 16% 18% ’10–’15 share gain: ~450 bps GMS Wallboard Market Share Adjusted EBITDA (2) Net Sales (1) Net sales do not reflect net sales attributable to acquired entities for any period prior to their respective dates of acquisition. FY 2015 and FY 2016 Adj. EBITDA includes approximately $8.1 million and $12.1 million, respectively, from entities acquired in FY 2015 and FY 2016, respectively, for the period prior to their respective dates of acquisition. However, Adj. EBITDA margin and the 5 year CAGR exclude the impact of the entities acquired for the period prior to their respective dates of acquisition. For a reconciliation of Adj. EBITDA to Net Income (loss), the most directly comparable GAAP metric, see Appendix. Includes the wallboard volume from entities acquired in FY 2015 assuming they were acquired on January 1, 2014. Includes the wallboard volume from entities acquired in FY 2016 assuming that the entities were acquired on January 1, 2015. (3) (4) Strategic Acquisition Opportunities in Highly Fragmented Market Continued Market Share Gains Greenfield Branch Openings Strong track record of executing profitable growth strategy 11 $106 $138 $8 $12 $18 $32 $58 $87 $114 $150 FY-11 FY-12 FY-13 FY-14 FY-15 FY-16 $881 $991 $1,162 $1,353 $1,570 $1,858 FY-11 FY-12 FY-13 FY-14 FY-15 FY-16 8.6% 8.8% 9.4% 9.9% 13.1% CY2010 CY2011 CY2012 CY2013 CY2014 CY2015 11.1 %

Source: Gypsum Association and GMS data. Includes the wallboard volume from entities acquired in fiscal 2015 assuming that the entities were acquired on January 1, 2014. Includes the wallboard volume from entities acquired in fiscal 2016 assuming that the entities were acquired on January 1, 2015. Strong History of Market Share Gains Organic Growth Drivers Significant Competitive Advantages: Scale and leading market positions drive competitive advantage Breadth of product availability and access to leading brands and latest product innovations Highly trained workforce delivering differentiated service offering High degree of logistics capabilities and expertise, and best-in-class execution Initiatives: Continue to expand retail showroom network within its branches Capitalize on its national homebuilder initiative Continue to strengthen relationships with manufacturers and customers via GMS’s national sales expo Deliver the latest product innovations in order to continue to provide holistic solutions to its customers Above Market Growth (1) 8.8% 9.4% 9.9% 11.1% GMS Wallboard Market Share (2) 13.1% (3) GMS has a proven history of growing faster than the market and gaining share 12 0.8% 10.0% 8.4% 4.9% 2.6% 2.4% 17.3% 14.8% 17.3% 21.7% CY2011 CY2012 CY2013 CY2014 CY2015 GMS Wallboard Volume Growth North American Wallboard Volume Growth

Acquisition Strategy Recent GMS Acquisitions February 2016 January 2016 November 2015 September 2015 April 2016 February 2016 November 2015 Tri-Cities Drywall & Supply Industry Structure: Large, highly fragmented industry comprised of ~400 competitors Similar business operations enable efficient integration Limited number of scaled players Acquisition Strategy: Criteria: leading capabilities in targeted new markets / increase existing network density / enhance strategic capabilities Fit GMS culture and platform Deliver scale benefits Attractive purchase price multiples Dedicated M&A team Pipeline: The majority of the market is comprised of local independent competitors representing significant opportunity Maintain active dialogue with many operators at any given time Given GMS’s employee-centric culture and track record in the industry, it is the acquirer of choice, positioning GMS to continue to drive growth through acquisitions Acquirer of Choice in Highly Fragmented Market July 2016 May 2016 Mach 2015 March 2015 February 2015 November 2014 October 2014 August 2014 13

Significant Opportunity to Further Expand the Platform GMS has a significant opportunity to expand its geographic footprint in under served and under penetrated markets through greenfields and acquisitions GMS has a demonstrated history of successful expansion through greenfields and acquisitions GMS has no presence in just under 50% of the top 100 MSAs in the U.S. Significant opportunity for share gains in new and existing markets over time Canada NE KS OK NM CO WY TX LA MS AR AL GA MO KY TN FL NC VA SC IA IL IN OH WV DC MD DE NJ PA NY CT RI MA NH VT SD ND MN MI WI AZ UT ID MT WA OR NV CA HI AK ME Current GMS Branch MSA with limited or no GMS Presence(1) GMS currently has limited or no branches in the areas identified as an MSA with no GMS presence. There can be no assurance that GMS will be able to expand into any of these areas. Additionally, in the event GMS takes measures to expand into these areas, there can be no assurance that GMS will be successful, and any such expansion will be subject to several risks including those discussed under the heading “Risk Factors” in its Annual Report on Form 10-K for the fiscal year ended April 30, 2016. 14

Capitalizing on Large and Diverse End Markets Poised for Continued Growth GMS’ business mix is diversified across commericial and residential as well as new construction and R&R end markets, all of which are expected to continue to see robust growth End markets still we below historic levels New Commercial ~(44%) below prior peak New Residential ~(46%) below prior peak Significant R& exposure, well below prior peak 15

Entrepreneurial Culture And Experienced Leadership Driving Superior Execution Significant management equity ownership with 71 employees owning ~26% (~30% including options); personally invested in the success and growth of the Company Attractive variable compensation structure, consisting of tiered, profit-based structure which incentivizes superior performance Unique culture combining a results driven environment with a highly entrepreneurial, self starter attitude Delivering consistent, above market growth Unwavering focus on operational excellence drives enhanced margin expansion and earnings growth Senior management averages 25 years in the industry and over 20 years with GMS VPs of Operations across all seven geographic divisions have 30+ years of industry experience and have worked with GMS for 25+ years on average Significantly enhanced Yard Support Center team with new leaders in finance, M&A, HR and legal Proven Track Record Significant Experience In The Industry Entrepreneurial / Ownership Culture 16

Financial Highlights Above-Market Growth Attractive Cash Flow Dynamics Continued margin improvement Attractive End Market Dynamics Proven track record of driving consistent above market growth and share gains Ability to deliver superior service and a comprehensive product suite Well positioned to capitalize on recovery in construction end markets Balanced exposure to residential, commercial and R&R end-markets providing tailwinds across the cycle Poised to benefit from significant operating leverage Ongoing focus on cost management and operational efficiency Low capex requirements to fund growth Proven history of generating strong free cash flows (1) Free cash flow defined as adjusted EBITDA less capex. Well positioned to drive continued above-market growth 17

Record Fiscal Q4 2016 and FY 2016 Sales Net Sales ($ mm) Fiscal Q4 2016 Net Sales (1) +30.3% YOY (5) Net Sales ($ mm) Twelve Months 2016 Net Sales (1) +18.3% YOY GMS continues to outpace construction end market expansion (5) +16.0% Base Business YOY +7.6% Base Business YOY Completed three acquisitions in Fiscal Q4 2016 and seven in FY 2016 Net sales do not reflect net sales attributable to acquired entities for any period prior to their respective dates of acquisition. When calculating its “base business” results, GMS excludes any branches that were acquired in the current fiscal year, prior fiscal year and three months prior to the start of the prior fiscal year. $1,570.1 $404.5 $527.2 Fiscal Q4 2016 Performance Twelve Months 2016 Performance 18 ($ in millions) Fiscal Q4 YOY Base 4/30/15 4/30/16 Growth Business (2) Wallboard Volume (MSF) 600 816 36.0% 18.9% Wallboard Price ($/'000 Sq. Ft.) 315 $ 305 $ (3.2%) Net Sales Wallboard 189.0 $ 248.8 $ 31.6% 16.7% Ceilings 69.4 78.2 12.6% 6.4% Steel Framing 58.5 77.8 33.0% 16.9% Other Products 87.6 122.4 39.8% 22.4% Total Net Sales 404.5 $ 527.2 $ 30.3% 16.0% ($ in millions) Fiscal Q4 YTD YOY Base 4/30/15 4/30/16 Growth Business (2) Wallboard Volume (MSF) 2,328 2,843 22.1% 9.9% Wallboard Price ($/'000 Sq. Ft.) 309 $ 306 $ (0.7%) Net Sales Wallboard 718.1 $ 871.0 $ 21.3% 9.7% Ceilings 278.7 297.1 6.6% 3.1% Steel Framing 243.2 281.3 15.7% 3.2% Other Products 330.0 408.8 23.9% 10.5% Total Net Sales 1,570.1 1,858.2 18.3% 7.6%

Continued Margin Expansion in Fiscal Q4 2016 and FY 2016 Gross Profit ($ mm) Fiscal Q4 2016 Adjusted Gross Profit & Margin (1) (5) Adj. EBITDA ($ mm) Fiscal Q4 2016 Adjusted EBITDA (2) Gross Profit ($ mm) FY 2016 Adjusted Gross Profit & Margin (1) Tailored investments in Yard Support Center, IT and branch talent to support expanding activity are paying off $29.8 (5) Adj. EBITDA ($ mm) FY 2016 Adjusted EBITDA (2) $113.9 Excludes cost of sales impact of purchase accounting adjustments. See page 15 for GAAP metric. Fiscal Q4 2015, FY 2015, Fiscal Q4 2016 and FY 2016 Adj. EBITDA includes approximately $1.0 million, $8.1 million, $0.1 million, and $12.1 million, respectively, from entities acquired in FY 2015 and FY 2016, respectively, for the period prior to their respective dates of acquisition. However, Adj. EBITDA margin excludes the impact of the entities acquired for the period prior to their respective dates of acquisition. For a reconciliation of Adj. EBITDA to Net Income (loss), the most directly comparable GAAP metric, see Appendix. $43.7 +32.0% YOY Margin(2): 7.1% 8.3% Margin(2): 6.7% 7.4% 19

Attractive Capital Structure Pro forma leverage of ~3.2x Net Debt / LTM Adj. EBITDA as of 4/30/16, after use of net proceeds from IPO together with cash on hand to pay off $160 million Second Lien Term Loan Continued improvement in credit metrics from 6.0x Net Debt / LTM Adj. EBITDA as of 4/30/14 and 4.9x as of 4/30/15 $275.0 million of our variable rate debt is capped at 5.75% through October 31, 2018 There remains a significant degree of liquidity in the business, with $19 million of cash on hand and an additional $187 million undrawn on the ABL facility as of 4/30/16 Commentary Leverage Summary Net Debt / Adjusted EBITDA Note: Fiscal year end April 30. 20 ($ mm) 4/30/14 4/30/15 4/30/16 4/30/16 FYE FYE FYE PF Cash $33 $12 $19 $16 US Asset-Based Revolver - 17 102 102 First Lien Term Loan 390 386 382 382 Second Lien Term Loan 160 160 160 - Capital Lease and Other 2 10 14 14 Total Debt $552 $573 $658 $498 LTM PF Adj. EBITDA $87 $114 $150 $150 Total Debt / LTM Adj. EBITDA 6.3x 5.0x 4.4x 3.3x Net Debt / LTM Adj. EBITDA 6.0x 4.9x 4.3x 3.2x 6.0x 4.9x 4.3x 3.2x 4/30/14 4/30/15 4/30/16 4/30/16 PF

Appendix

Net Income to Adjusted EBITDA Non-GAAP Adjusted EBITDA Reconciliation Commentary Represents compensation paid to certain executives who were majority owners prior to the AEA acquisition of GMS. Following the acquisition, these executives’ compensation agreements were amended and, going forward, GMS does not anticipate additional adjustments Represents non-cash compensation expenses related to stock appreciation rights agreements Represents non-cash compensation expense related to changes in the redemption values of noncontrolling interests Represents non-cash equity-based compensation expense related to the issuance of stock options Represents non-recurring expenses related specifically to the AEA acquisition of GMS Represents severance and other costs for discontinued operations and branch closures One-time costs related to the IPO and acquisitions (other than the AEA acquisition) paid to third party advisors Represents management fees paid to AEA, which were discontinued after the IPO Non-cash cost of sales impact of purchase accounting adjustments to increase inventory to its estimated fair value, primarily related to the AEA acquisition Mark to market adjustments for certain financial instruments Full year (i.e. predecessor) pro forma impact of acquisitions made during FY 2015 and FY 2016 Represents costs incurred in connection with withdrawal from a multi-employer pension plan FY14 is comprised of 11 month period (predecessor) and one month period (successor) 22 ($ in 000s) Fiscal Year Ending April 30, (Unaudited) 2016 2015 2014 (1) 2013 2012 2011 Net income (loss) $ 12,564 $ (11,697) $(219,814) $(182,627) $ (7,830) $ (6,939) Income tax expense (benefit) 12,584 (6,626) (240) 11,534 2,658 2,086 Discountinued operations, net of tax - - - - (362) 23 Interest income (928) (1,010) (922) (798) (885) (711) Interest expense 37,418 36,396 7,180 4,413 2,966 3,236 Change in fair value of mandatorily redeemable shares - 200,004 198,212 8,952 6,978 Depreciation expense 26,667 32,208 16,042 11,665 7,840 7,136 Amortization expense 37,548 31,957 2,556 72 732 4,239 EBITDA $125,853 $ 81,228 $ 4,806 $ 42,471 $ 14,071 $ 16,048 Adjustments Executive compensation (A) $ - $ - $ 2,447 $ 13,420 $ 8,266 $ 3,413 Stock appreciation rights expense (benefit) (B) 1,988 2,268 1,368 1,061 253 (47) Redeemable noncontrolling interests (C) 880 1,859 3,028 2,195 407 (245) Equity-based compensation (D) 2,699 6,455 28 82 (154) (114) AEA transaction related costs (E) - 837 67,964 230 133 53 Severance costs and discontinued operations (F) 379 413 - (30) (205) (824) Transaction costs (acquisition and other) (G) 3,751 1,891 - - - - (Gain) loss on disposal of assets (645) 1,089 (864) (2,231) (556) 14 AEA management fee (H) 2,250 2,250 188 - - - Effects of fair value adjustments to inventory (I) 1,009 5,012 8,289 - - - Interest rate swap / cap mark-to-market (J) 19 2,494 (192) 313 - (586) Contributions from acquisitions (K) 12,093 8,064 - Pension withdrawal (L) - - - - 10,179 - Total Add-Backs 24,423 32,632 82,256 15,040 18,323 1,664 Adjusted EBITDA $150,276 $113,860 $ 87,062 $ 57,511 $ 32,394 $ 17,712

Quarterly Financials Summary Quarterly Financials Note: Fiscal year end April 30. 23 (In millions, except per share data) 1Q15 2Q15 3Q15 4Q15 FY15 1Q16 2Q16 3Q16 4Q16 FY16 (Unaudited) Wallboard Volume (MSF) 578 613 537 600 2,328 681 700 646 816 2,843 Wallboard Price ($ / '000 Sq. Ft.) 307 $ 305 $ 307 $ 315 $ 309 $ 310 $ 306 $ 305 $ 305 $ 306 $ Wallboard 177 $ 187 $ 165 $ 189 $ 718 $ 211 $ 214 $ 197 $ 249 $ 871 $ Ceilings 72 74 63 69 279 79 75 65 78 297 Steel framing 64 65 56 58 243 67 70 66 78 281 Other products 82 87 74 88 330 95 99 92 122 409 Net sales 394 413 358 404 1,570 452 458 420 527 1,858 Cost of sales (exclusive of depreciation and amortization shown separately below) 280 287 246 278 1,091 312 314 286 353 1,265 Gross profit 115 126 112 126 479 141 144 134 174 593 Operating expenses: Selling, general and administrative expenses 96 99 98 103 396 110 114 112 133 470 Depreciation and amortization 17 16 16 16 64 16 15 16 17 64 Total operating expenses 113 115 113 119 460 126 130 128 150 534 Operating income (loss) 2 11 (1) 7 19 15 14 6 24 59 Other (expense) income: Interest expense (9) (9) (9) (9) (36) (9) (9) (9) (9) (37) Change in fair value of financial instruments - - (2) - (2) - - - (0) (0) Other income, net 1 0 0 0 2 1 0 1 2 4 Total other (expense), net (9) (9) (11) (8) (37) (9) (9) (9) (7) (34) Income (loss) from continuing operations, before tax (7) 2 (12) (2) (18) 6 5 (3) 17 25 Income tax expense (benefit) (1) (0) (1) (4) (7) 3 3 (1) 8 13 Net income (loss) (6) 3 (11) 2 (12) 3 3 (2) 9 13 Weighted average shares outstanding: Basic 32,342 32,413 32,499 32,551 32,450 32,677 32,738 32,891 32,893 32,799 Diluted 32,342 32,413 32,499 32,684 32,450 32,831 32,898 32,891 33,155 33,125 Net income (loss) per share: Basic (0.17) $ 0.08 $ (0.34) $ 0.07 $ (0.36) $ 0.09 $ 0.09 $ (0.07) $ 0.27 $ 0.38 $ Diluted (0.17) $ 0.08 $ (0.34) $ 0.07 $ (0.36) $ 0.09 $ 0.09 $ (0.07) $ 0.27 $ 0.38 $

Quarterly Sales Note: Fiscal year end April 30. When calculating its “base business” results, GMS excludes any branches that were acquired in the current fiscal year, prior fiscal year and three months prior to the start of the prior fiscal year. Quarterly business days for FY17 are 63, 65, 63 and 63 for 1Q17, 2Q17, 3Q17 and 4Q17, respectively. Includes greenfields, which GMS considers extensions of “base business.” 24 ($ in millions) 1Q15 2Q15 3Q15 4Q15 FY15 1Q16 2Q16 3Q16 4Q16 FY16 (Unaudited) Base Business (1) 394 $ 406 $ 347 $ 378 $ 1,526 $ 415 $ 420 $ 369 $ 439 $ 1,642 $ Acquisitions 7 11 26 44 38 38 52 88 216 Total Net Sales 394 $ 413 $ 358 $ 404 $ 1,570 $ 452 $ 458 $ 420 $ 527 $ 1,858 $ Business Days (2) 64 65 61 64 254 64 64 61 65 254 Net Sales by Business Day 6.2 $ 6.4 $ 5.9 $ 6.3 $ 6.2 $ 7.1 $ 7.2 $ 6.9 $ 8.1 $ 7.3 $ Base Business Branches (3) 141 143 143 143 143 143 145 146 148 148 Acquired Branches 2 5 6 13 13 13 14 32 38 38 Total Branches 143 148 149 156 156 156 159 178 186 186

Quarterly Net Income to Adjusted EBITDA GAAP Adjusted EBITDA Reconciliation Commentary Represents non-cash compensation expenses related to stock appreciation rights agreements Represents non-cash compensation expense related to changes in the redemption values of noncontrolling interests Represents non-cash equity-based compensation expense related to the issuance of stock options Represents non-recurring expenses related specifically to the AEA acquisition of GMS Represents severance and other costs for discontinued operations and branch closures One-time costs related to the IPO and acquisitions (other than the AEA acquisition) paid to third party advisors Represents management fees paid to AEA, which were discontinued after the IPO Non-cash cost of sales impact of purchase accounting adjustments to increase inventory to its estimated fair value, primarily related to the AEA acquisition Mark to market adjustments for certain financial instruments Full year (i.e. predecessor) pro forma impact of acquisitions made during FY 2015 and FY 2016 25 ( $ in 000s) 1Q15 2Q15 3Q15 4Q15 FY15 1Q16 2Q16 3Q16 4Q16 FY16 (Unaudited) Net Income (Loss) (5,548) $ 2,728 $ (11,013) $ 2,136 $ (11,697) $ 3,011 $ 2,825 $ (2,212) $ 8,940 $ 12,564 $ Add: Income Tax Expense (1,239) (266) (1,458) (3,663) (6,626) 2,855 2,623 (819) 7,925 12,584 Less: Discontinued Operations, net of tax - - - - - - - - - - Less: Interest Income (305) (244) (238) (223) (1,010) (230) (208) (247) (243) (928) Add: Interest Expense 9,137 9,226 9,162 8,871 36,396 9,257 9,260 9,473 9,428 37,418 Add: Depreciation Expense 9,284 8,097 7,628 7,199 32,208 7,273 6,465 6,469 6,460 26,667 Add: Amortization Expense 7,560 7,714 7,885 8,798 31,957 8,792 8,797 9,540 10,419 37,548 EBITDA 18,889 $ 27,255 $ 11,966 $ 23,118 $ 81,228 $ 30,958 $ 29,762 $ 22,204 $ 42,929 $ 125,853 $ Adjustments Stock appreciation rights expense (benefit) (A) 451 663 391 763 2,268 594 692 337 365 1,988 Redeemable noncontrolling interests (B) 455 452 249 703 1,859 554 451 167 (292) 880 Equity-based compensation (C) 1,864 1,586 1,659 1,346 6,455 498 863 728 610 2,699 AEA transaction related costs (D) 492 345 - - 837 - - - - - Severance costs and discontinued operations (E) - 163 100 150 413 557 824 52 (1,054) 379 Transaction costs (acquisition and other) (F) - 119 157 1,615 1,891 415 1,340 1,057 939 3,751 Loss (gain) on disposal of assets 450 77 312 250 1,089 (25) 305 (205) (720) (645) AEA management fee (G) 562 563 562 563 2,250 562 563 562 563 2,250 Effects of fair value adjustments to inventory (H) 4,486 - 260 266 5,012 - - 786 223 1,009 Interest rate swap / cap mark-to-market (I) - - 2,494 - 2,494 - - - 19 19 Contributions from acquisitions (J) 2,636 3,023 1,400 1,005 8,064 4,896 4,991 2,073 132 12,093 Total Add-Backs 11,396 $ 6,991 $ 7,584 $ 6,661 $ 32,632 $ 8,051 $ 10,029 $ 5,557 $ 785 $ 24,423 $ Adjusted EBITDA 30,285 $ 34,246 $ 19,550 $ 29,779 $ 113,860 $ 39,009 $ 39,791 $ 27,761 $ 43,714 $ 150,276 $

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