Exhibit 99.1

Armstrong World Industries Reports

Third Quarter 2020 Results

Key Highlights

LANCASTER, Pa., October 27, 2020 -- Armstrong World Industries, Inc. (NYSE:AWI), a leader in the design, innovation and manufacture of commercial and residential ceiling, wall and suspension system solutions, today reported financial results for the third quarter of 2020.

Net sales decreased compared to the prior year quarter, driven by lower volume in both the Mineral Fiber and Architectural Specialties segments as a result of lower market demand due to COVID-19, as well as unfavorable Mineral Fiber AUV primarily due to regional weakness in major metropolitan areas heavily impacted by COVID-19 and channel mix, partially offset by the positive sales impact of 2020 and 2019 acquisitions.

Operating income decreased from the prior year quarter, driven primarily by lower sales volume in the Mineral Fiber segment and lower earnings from our WAVE joint venture, partially offset by improved manufacturing productivity. Equity earnings in the third quarter of 2019 included a net $21 million gain on WAVE’s sale of its European and Pacific Rim businesses.

“As expected, we saw a sequentially better demand environment in the third quarter, and we expect this improving trend to continue into the fourth quarter.  I am pleased that in a quarter impacted by a pandemic we were able to close on two more strategic acquisitions, Turf Design and Moz Designs, our sixth and seventh acquisitions since 2017.  Turf gives us the leading position in the growing category of felt ceilings, walls and barriers, and Moz extends our leadership position and capabilities in metal ceilings, walls and column covers,” said Vic Grizzle, President and CEO of Armstrong.  “Ceilings play a critical role in the creation of healthy spaces and our recently announced 24/7 Defend line of products represent innovative new solutions to enable everyone to get back to life and work in a healthy and safe way.”

* The Company uses the above non-GAAP adjusted measures in managing the business and believes the adjustments provide meaningful comparisons of operating performance between periods.  The Company also believes that the adjustments help users of our financial information understand the effect of those adjusted items on our selected reported results and provide useful alternative measurements of performance.  See Supplemental Reconciliations of GAAP to non-GAAP results (below) for a breakdown of the adjustments and a reconciliation of the selected reported results to these non-GAAP measures.

Consolidated adjusted EBITDA declined 19% in the third quarter when compared to the same prior year period, driven primarily by lower sales volume, unfavorable AUV and a decrease in WAVE earnings, partially offset by improved manufacturing productivity. Adjusted free cash flow declined primarily due to lower cash earnings driven by volume declines.

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Mineral Fiber net sales decreased due to lower volume and unfavorable AUV. Unfavorable AUV was driven by mix due primarily to regional weakness in major metropolitan areas heavily impacted by COVID-19 and channel mix.  Like for like price was positive in the quarter.

Operating income decreased in the second quarter primarily due to the negative impact of lower sales volume, lower WAVE earnings and the impact of unfavorable AUV, partially offset by improved manufacturing productivity and a reduction in incentive compensation expenses.

Net sales in Architectural Specialties increased slightly due to sales from the recent acquisitions of Turf Design and Moz Designs, mostly offset by a reduction in demand as a result of the COVID-19 pandemic.

Operating income decreased due the negative impact of lower sales volume, excluding the impact of the 2019 and 2020 acquisitions, as well as additional amortization expense related to acquisitions.

Unallocated Corporate

Unallocated corporate income of $5.2 million increased from $1.8 million of expense in the prior year quarter primarily due to gains related to the sale of our idled Mineral Fiber plant in China.

Net sales decreased driven mainly by lower volumes in both the Mineral Fiber and Architectural Specialties segments as a result of the COVID-19 pandemic and unfavorable AUV in the Mineral Fiber segment.

Operating income decreased from the prior year period, primarily due to impact of decreased sales, partially offset by lower SG&A expense, the gain on sale of the idled China plant, and improved manufacturing productivity.

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Market Outlook and 2020 Guidance

“Assuming continued sequential market improvement and no second wave of construction site shutdowns, we expect sales for the full year in the range of $920-$935 million, adjusted EBITDA in the range of $320-$330 million, and adjusted free cash flow of $200-$210 million,” said Brian MacNeal, CFO of Armstrong. “With a strong balance sheet and ample liquidity, we continue to remain confident in our ability to execute on our long-term value creation strategy.”

Earnings Webcast

Management will host a live internet broadcast beginning at 11:00 a.m. eastern time today, to discuss third quarter 2020 results. This event will be broadcast live on the Company's website. To access the call and accompanying slide presentation, go to www.armstrongceilings.com and click Investors. The replay of this event will also be available on the Company's website for up to one year after the date of the call.

Uncertainties Affecting Forward-Looking Statements

Disclosures in this release, including without limitation, those relating to future financial results, market conditions and guidance, and in our other public documents and comments, contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Those statements provide our future expectations or forecasts and can be identified by our use of words such as “anticipate,” “estimate,” “expect,” “project,” “intend,” “plan,” “believe,” “outlook,” “target,” “predict,” “may,” “will,” “would,” “could,” “should,” “seek,” and other words or phrases of similar meaning in connection with any discussion of future operating or financial performance. Forward-looking statements, by their nature, address matters that are uncertain and involve risks because they relate to events and depend on circumstances that may or may not occur in the future. As a result, our actual results may differ materially from our expected results and from those expressed in our forward-looking statements. A more detailed discussion of the risks and uncertainties that could cause our actual results to differ materially from those projected, anticipated or implied is included in the “Risk Factors” and “Management’s Discussion and Analysis” section of our report on Forms 10-K/A and 10-Q filed with the U.S. Securities and Exchange Commission (“SEC”). Forward-looking statements speak only as of the date they are made. We undertake no obligation to update any forward-looking statements beyond what is required under applicable securities law.

About Armstrong and Additional Information

More details on the Company’s performance can be found in its quarterly report on Form 10-Q for the quarter ended September 30, 2020 that the Company expects to file with the SEC today.

Armstrong World Industries, Inc. (AWI) is a leader in the design and manufacture of innovative commercial and residential ceiling, wall and suspension system solutions in the Americas. With over $1 billion in revenue in 2019, AWI has approximately 2,500 employees and a manufacturing network of 15 facilities, plus five facilities dedicated to its WAVE joint venture.

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Additional forward looking non-GAAP metrics are available on the Company’s website at www.armstrongceilings.com under the Investors tab. The website is not part of this release and references to our website address in this release are intended to be inactive textual references only.

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Supplemental Reconciliations of GAAP to non-GAAP Results (unaudited)

(Amounts in millions, except per share data)

To supplement its consolidated financial statements presented in accordance with accounting principles generally accepted in the United States (“GAAP”), the Company provides additional measures of performance adjusted to exclude the impact of certain discrete expenses and income.  Investors should not consider non-GAAP measures as a substitute for GAAP measures.  Examples of excluded items include plant closures, restructuring charges and related costs, impairments, separation costs, environmental site expenses and related insurance recoveries, and certain other gains and losses. The Company also excludes income/expense from its U.S. Retirement Income Plan (“RIP”) in the non-GAAP results as it represents the actuarial net periodic benefit credit/cost recorded. For all periods presented, the Company was not required and did not make cash contributions to the RIP based on guidelines established by the Pension Benefit Guaranty Corporation, nor does the Company expect to make cash contributions to the plan in 2020. Adjusted free cash flow is defined as cash from operating and investing activities, adjusted to remove the impact of cash used or proceeds received for acquisitions and divestitures, legacy environmental matters and litigation. The Company believes adjusted free cash flow is useful because it provides insight into the amount of cash that the Company generates for discretionary uses, after expenditures for capital investments and adjustments for acquisitions and divestitures. The Company uses these adjusted performance measures in managing the business, including communications with its Board of Directors and employees, and believes that they provide users of this financial information with meaningful comparisons of operating performance between current results and results in prior periods. The Company believes that these non-GAAP financial measures are appropriate to enhance understanding of its past performance, as well as prospects for its future performance.  The Company also uses adjusted EBITDA and adjusted free cash flow as factors in determining at-risk compensation for senior management. These non-GAAP measures may not be defined and calculated the same as similar measures used by other companies.  A reconciliation of these adjustments to the most directly comparable GAAP measures is included in this release and on the Company’s website. These non-GAAP measures should not be considered in isolation or as a substitute for the most comparable GAAP measures. Non-GAAP financial measures utilized by the Company may not be comparable to non-GAAP financial measures used by other companies.

In the following charts, numbers may not sum due to rounding.

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(1) U.S. pension expense represents only the service cost related to the RIP that is recorded within Operating Income. For all periods presented, we were not required and did not make cash contributions to our RIP.

(2) WAVE settled a portion of their pension plan, resulting in a non-cash accounting charge.

(3) Represents Rockfon litigation costs and settlement.

(4) WAVE Fresh Start Accounting asset amortization.

(1) WAVE settled a portion of their pension plan, resulting in a non-cash accounting charge.

(2) Represents Rockfon litigation costs and settlement.

(3) WAVE Fresh Start Accounting asset amortization.

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(1) U.S. pension expense represents only the service cost related to the U.S. pension plan that is recorded within Operating Income. For all periods presented, we were not required and did not make cash contributions to our U.S. Retirement Income Plan.

(1)  Includes related income tax impacts

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(1) RIP expense (credit) represents the entire actuarial net periodic pension expense (credit) recorded as a component of earnings from continuing operations. For all periods presented, we were not required and did not make cash contributions to our RIP.

(2) WAVE settled a portion of their pension plan, resulting in a non-cash accounting charge.

(3) Represents Rockfon litigation costs and settlement.

(4) WAVE Fresh Start Accounting asset amortization.

(5) Adjusted income tax expense is calculated using the as reported tax rate multiplied by the adjusted earnings from continuing operations before income taxes.

(6) 2020 Dilutive shares outstanding for the nine months ended September 30, 2020 include anti-dilutive common stock equivalents which are excluded from U.S. GAAP accounting. Dilutive shares outstanding for the three months ended September 30, 2020 and for the three and nine months ended September 30, 2019 are as-reported.

(7) The tax rate for the nine months ended September 30, 2020 excludes Q1 pension annuitization and the gain on the sale of our idled China facility and for 2019 is our actual tax rate excluding WAVE’s gain on sale to Knauf.

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(1) RIP Expense represents the actuarial net periodic benefit expected to be recorded as a component of other non-operating income. We do not expect to be and do not plan to make cash contributions to our U.S. Retirement Income Plan based on guidelines established by the Pension

Benefit Guaranty Corporation.

(2) U.S. pension expense represents only the service cost related to the U.S. pension plan that is recorded within Operating Income. For all periods presented, we were not required and did not make cash contributions to our U.S. Retirement Income Plan.

(1) Adjusted EPS guidance for 2020 is calculated based on an adjusted effective tax rate of 25% and based on ~48 million of diluted shares outstanding.

(2) RIP expense represents the actuarial net periodic benefit expected to be recorded as a component of other non-operating income. We do not expect to be required to make, nor do we plan to make cash contributions to our U.S. Retirement Income Plan based on guidelines established by the Pension Benefit Guaranty Corporation.

(3) RIP expense represents only the service cost related to the U.S. pension plan and is recorded as a component of operating income. We do not expect to be required to make, nor do we plan to make cash contributions to our U.S. Retirement Income Plan based on guidelines established by the Pension Benefit Guaranty Corporation.

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Earnings Call Presentation 3rd Quarter 2020 October 27, 2020 Exhibit 99.2

Our disclosures in this presentation, including without limitation, those relating to future financial results market conditions and guidance, and in our other public documents and comments contain forward-looking statements within the meaning of the Private Securities Litigation Reform Act. Those statements provide our future expectations or forecasts and can be identified by our use of words such as “anticipate,” “estimate,” “expect,” “project,” “intend,” “plan,” “believe,” “outlook,” “target,” “predict,” “may,” “will,” “would,” “could,” “should,” “seek,” and other words or phrases of similar meaning in connection with any discussion of future operating or financial performance. Forward-looking statements, by their nature, address matters that are uncertain and involve risks because they relate to events and depend on circumstances that may or may not occur in the future. As a result, our actual results may differ materially from our expected results and from those expressed in our forward-looking statements. A more detailed discussion of the risks and uncertainties that may affect our ability to achieve the projected performance is included in the “Risk Factors” and “Management’s Discussion and Analysis” sections of our reports on Forms 10-K and 10-Q filed with the U.S. Securities and Exchange Commission (“SEC”). Forward-looking statements speak only as of the date they are made. We undertake no obligation to update any forward-looking statements beyond what is required under applicable securities law. In addition, we will be referring to non-GAAP financial measures within the meaning of SEC Regulation G. A reconciliation of the differences between these measures with the most directly comparable financial measures calculated in accordance with GAAP are included within this presentation and available on the Investor Relations page of our website at www.armstrongceilings.com. The guidance in this presentation is only effective as of the date given, October 27, 2020 and will not be updated or affirmed unless and until we publicly announce updated or affirmed guidance Safe Harbor Statement

All figures throughout the presentation are in $ millions unless otherwise noted. Figures may not add due to rounding. When reporting our financial results within this presentation, we make adjustments to normalize the results. Management uses these non-GAAP measures in managing the business and believes the adjustments provide meaningful comparisons of operating performance between periods. As reported results will be footnoted throughout the presentation. Basis of Presentation Explanation Results throughout this presentation are presented on a normalized basis with the exception of cash flow. We remove the impact of certain discrete expenses and income. Examples include plant closures, restructuring actions, separation costs, environmental site expenses and related insurance recoveries, and other large unusual items. We also adjust for our U.S. pension plan (credit) expense(1). Our tax rate is adjusted for certain discrete items which are identified in the footnotes Investors should not consider non-GAAP measures as a substitute for GAAP measures. U.S. pension (credit) expense represents the actuarial net periodic benefit cost expected to be recorded as a component of earnings from continuing operations. For all periods presented, we were not required and did not make cash contributions to our U.S. Retirement Income Plan based on guidelines established by the Pension Benefit Guaranty Corporation.

Consolidated Company Key Metrics-Third Quarter 2020 As reported EPS: $1.13 in 2020 and $1.83 in 2019. As defined by the terms of our credit agreement 2020 2019 Variance Net Sales $246.3 $0 $277.10000000000002 -0.11115120894983765 Adj. EBITDA $91.745457000000002 $0 $113.5 $0 -0.19166998237885458 % of Sales 0.37249475030450668 0.40959942259112231 -370 bps hardcode watchout Adj. Earnings Per Share (1) $1.072229055775697 $1.3800238847777779 -0.223035870898455 Adj. Free Cash Flow $46 $99 -0.53535353535353536 Cash $138.80000000000001 $98 $40.800000000000011 Revolver Availability $315 $380 $-65 Liquidity $453.8 $478 $-24.199999999999989 Net Debt $542 $538 $4 Leverage(2) 1.5x 1.6x Favorable

COVID-19 impacts demand Manufacturing gains driven by productivity Sales continued to improve sequentially in the quarter Mineral Fiber Third Quarter Results Sales improving sequentially as major metro areas reopen Key Highlights Q1 Q2 Q3 2019 Adjusted EBITDA $82 $96 $99 Current Quarter Comments AUV (5) (5) (4) Positive price offset by channel and geographic mix Volume 0 (36) (21) COVID-19 market disruption Manufacturing 5 7 5 Continued productivity gains and cost out actions Input costs 0 4 2 Lower raw material and energy costs SG&A 4 5 4 Cost out actions WAVE 1 (9) (7) Volume impacted by COVID-19 2020 Adjusted EBITDA $87 $63 $79 Margins contracted 330 bps in Q3 % Change 6% (35%) (21%)

Sales up 1% as acquisitions of Turf Design and Moz Designs add $8 million Architectural Specialties Third Quarter Results Acquisitions offset COVID headwinds Key Highlights Q1 Q2 Q3 2019 Adjusted EBITDA $10 $12 $14 Current Quarter Comments Sales 4 (2) 5 Direct margin improvement relating to acquisitions Period Expense (2) (3) (3) Manufacturing expenses relating to acquisitions SG&A (2) (1) (4) SG&A expenses relating to acquisitions 2020 Adjusted EBITDA $10 $6 $13 Margins contracted 720 bps in Q3 % Change (2%) (48%) (9%)

Adjusted EBITDA Bridge – Third Quarter 2020 vs. PY ($16) ($4) $2 ($0) $3 ($7) Lower volumes due to COVID-19… Sequential improvement within quarter Normalized(1) May not sum due to rounding

Adjusted Free Cash Flow Bridge - Third Quarter 2020 vs. PY $2 Cash earnings decline driven by volume declines due to Covid-19 ($48) $2 ($6) (2) NOTE: Adjustments include cash used or proceeds received for acquisitions and divestures, legacy environmental matters and litigation May not sum due to rounding Includes cash earnings, working capital and other current assets and liabilities Normalized(1) $46 ($3)

Consolidated Company Key Metrics – YTD 2020 As reported EPS: ($2.48) in 2020 and $3.84 in 2019. 2020 2019 Variance Net Sales $698.2 $0 $791.2 -0.1175429726996966 Adj. EBITDA $257.29755599999999 $0 $313.53100000000001 $0 -0.17935529182122345 % of Sales 0.36851554855342306 0.39627275025278058 -280 Adj. Earnings Per Share (1) $2.86 $3.66 -0.21857923497267762 Adj. Free Cash Flow $145 $173 -0.16184971098265896

Adjusted EBITDA Bridge – YTD 2020 vs. PY ($50) ($14) $7 $6 $8 ($15) Balancing short-term cost containment with long-term growth drivers

Adjusted Free Cash Flow Bridge – YTD 2020 vs. PY ($39) Cash earnings decline driven by volume declines due to Covid-19 $11 $9 ($10) $0

2020 Guidance $3.50 – $3.70 (27%) – (23%) YoY $4.78 Adjusted EBITDA Adjusted EPS* Adjusted Free Cash Flow Revenue $1,038 $403 $920 - $935 (11%) – (10%) YoY $320 - $330 (21%) – (18%) YoY Flat AUV, negative volume Continued sequential improvement Includes recently announced acquisitions Manufacturing productivity Cost containment of $40 - $45 $55 - $60 of total capital expenditures Cash tax rate 25% $25 of cash interest expense Excludes $48 million benefit of one-off tax refund and China plant sale 2019 Actual 2020 Guidance $25 of interest expense 25% book tax rate 48 million average diluted shares outstanding $200 - $210 (18%) – (14%) YoY 22% FCF Margin $244 *As reported EPS: $4.88 in 2019 All projections assume sequential market improvement and no second wave of construction site shutdowns

Appendix

Adjusted EBITDA Reconciliation U.S. pension expense represents only the service cost related to the RIP that is recorded within Operating Income. For all periods presented, we were not required and did not make cash contributions to our RIP. WAVE settled a portion of their pension plan, resulting in a non-cash accounting charge. Represents Rockfon litigation costs and settlement. WAVE Fresh Start Accounting asset amortization. CONSOLIDATED For the Three Months Ended September 30, For the Nine Months Ended September 30, qtr YTD 2020 2019 V 2020 2019 V Earnings (Loss) from continuing operations, Reported 54 91 -37 -119 191 -310 rounding Add: Income tax expense (benefit), as reported 15 16 -1 -51 49 -100 Earnings (Loss) before tax, Reported 69 107 -38 -170 240 -410 rounding Add: Interest/other income and expense, net 3 7 -4 381 16 365 Operating Income, Reported 72 113 -41 211 255 -44 Add: RIP Cost (1) 1 1 0 4 4 0 Add: WAVE Pension Settlement (2) 0 0 0 0 1 -1 Add: Litigation Expense (3) 0 0 0 0 20 -20 Add: Net Proforma International Allocations, Other 0 1 -1 0 0 0 Add: Net Environmental Expenses 0 1 -1 1 1 0 (Less): Gain on Sale of Idled China Plant Facility -7 0 -7 -21 0 -21 Add: WAVE FSA (4) 0 4 -4 0 4 -4 (Less): AWI Portion of WAVE's Gain on Sale to Knauf 0 -25 25 0 -25 25 Add: D&A 25 19 6 62 53 9 Adjusted EBITDA 92 114 -22 257 314 -57 rounding -0.19298245614035092 -0.18152866242038215

Adjusted Diluted Earnings Per Share Reconciliation RIP expense (credit) represents the entire actuarial net periodic pension expense (credit) recorded as a component of earnings from continuing operations. For all periods presented, we were not required and did not make cash contributions to our RIP. WAVE settled a portion of their pension plan, resulting in a non-cash accounting charge. Represents Rockfon litigation costs and settlement. WAVE Fresh Start Accounting asset amortization. Adjusted income tax expense is calculated using the as reported tax rate multiplied by the adjusted earnings from continuing operations before income taxes. 2020 Dilutive shares outstanding for the nine months ended September 30, 2020 include anti-dilutive common stock equivalents which are excluded from U.S. GAAP accounting. Dilutive shares outstanding for the three months ended September 30, 2020 and for the three and nine months ended September 30, 2019 are as-reported. The tax rate for the nine months ended September 30, 2020 excludes Q1 pension annuitization and the gain on the sale of our idled China facility and 2019 is actual tax rate excluding WAVE’s gain on sale to Knauf. CONSOLIDATED For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 Per Diluted 2019 Per Diluted V 2020 Per Diluted 2019 Per Diluted V Share Share Share Share Earnings (Loss) from continuing operations, As Reported $54 $1.1299999999999999 $91 $1.28 $-37 $-,119 $-2.48 $191 $3.84 $-,310 Add/(Less): Income tax expense (benefit), as reported $15 $16 $-1 $-51 $49 $-,100 Earnings (Loss) from continuing operations before income taxes, As Reported $69 $107 $-38 $-,170 $240 $-,410 Add/(Less): RIP Expense (Credit) (1) 0 $-2 $2 $370 $-6 $376 Add: WAVE Pension Settlement (2) 0 0 0 0 $1 $-1 Add: Litigation Expense (3) 0 0 0 0 $20 $-20 Add: Net Proforma International Allocations, Other 0 $1 $-1 0 0 0 Add: Net Environmental Expenses 0 $1 $-1 $1 $1 0 Add: WAVE FSA (4) 0 $4 $-4 0 $4 $-4 $0 (Less): Gain on Sale of Idled China Plant Facility $-7 0 $-7 $-21 0 $-21 0 Add: Accelerated Depreciation from closed St. Helens facility $3.2 0 $3.2 $3.2 0 $3.2 (Less): AWI Portion of WAVE's (gain) on Sale to Knauf 0 $-25 $25 0 $-25 $25 Adjusted earnings from continuing operations before income taxes $65.900543000000027 $85 $-19.099456999999973 $183.14378000000002 $235 $-51.856219999999979 (Less): Adjusted Income tax expense (5) $-14.433548322766573 $-17 $2.5664516772334274 $-45.053369880000005 $-54 $8.9466301199999947 Adjusted net income $51.466994677233458 $1.072229055775697 $68 $1.38 $-16.533005322766542 $138.09041012 $2.86 $181 $3.66 $-42.909589879999999 Adjusted EPS Change versus Prior Year -0.22303587089845506 -0.21857923497267767 Diluted Shares Outstanding (6) 48 49.5 48.3 49.6 Tax Rate (7) 0.22 0.2 0.246 0.23

Adjusted Free Cash(1) Flow Reconciliation Adjusted free cash flow is defined as cash from operations and dividends received from the WAVE joint venture, less expenditures for property and equipment, and is adjusted to remove the impact of cash used or proceeds received for acquisitions and divestitures, legacy environmental matters and litigation. The Company believes adjusted free cash flow is useful because it provides insight into the amount of cash that the Company has available for discretionary uses, after expenditures for capital commitments and adjustments for acquisitions and divestitures. Free cash flow includes discontinued international operations. Includes related income tax impacts For the Three Months Ended September 30, For the Nine Months Ended September 30, 2020 2019 V 2020 2019 V Net cash provided by operating activities $69 $74 $-5 $148 $121 $27 Net cash (used for) investing activities $-63 $-39 $-24 $-52 $-71 $19 Add: Acquisitions, net $74 - $66 $74 $43 $31 Add: Litigation, net - - - - $20 $-20 Add/(Less): Environmental Payments (Recoveries), net - $9 $-9 $1 $4 $-3 (Less)/Add: Proceeds from sale of international, net (2) $-20 $55 $-75 $-21 $55 $-76 Add: Net Payments to WAVE for Portion of Proceeds from Sale of International Businesses $3 - $3 $13 - $13 (Less): Proceeds from sale of Idled China Plant Facility $-19 - $-19 $-19 - $-19 Adjusted Free Cash Flow $46 $99 $-53 $145 $173 $-28 -0.53535353535353536 -0.16184971098265896

Segment Reported Operating Income (Loss) to Adjusted EBITDA U.S. pension expense represents only the service cost related to the RIP that is recorded within Operating Income. For all periods presented, we were not required and did not make cash contributions to our RIP. WAVE Fresh Start Accounting asset amortization. MINERAL FIBER ARCHITECTURAL SPECIALTIES UNALLOCATED CORPORATE For the Three Months Ended September 30, 2016 V 2020 2019 V 2020 2019 V 2020 2019 V Operating Income (Loss) – As Reported 58 104 -46 9 12 -3 5 -2.1 7.1 Add: RIP Cost (1) 0 0 0 0 0 0 1.3660650000000001 1.1902507499999999 0 Add: Net Proforma International Allocations, Other 0 1 -1 0 0 0 0 0 0 Add: Net Environmental Expenses 0 1 -1 0 0 0 0 0 0 (Less): Gain on Sale of Idled China Plant Facility 0 0 0 0 0 0 -7 0 -7 Add: WAVE FSA (2) 0 4 -4 0 0 0 0 0 0 (Less): AWI Portion of WAVE's (gain) on Sale to Knauf 0 -25 25 0 0 0 0 0 0 Add: Depreciation and Amortization 20 16 4 4 3 1 0 0.90974925000000018 -0.90974925000000018 EBITDA – Adjusted 78.84 99.3 -20.459999999999994 12.9 14.2 -1.2999999999999989 0 0 0 -0.20604229607250746 -9.1549295774647765E-2

EBITDA – Guidance Reconciliation Adjusted EBITDA RIP Expense represents the actuarial net periodic benefit expected to be recorded as a component of other non-operating income. We do not expect to be and do not plan to make cash contributions to our U.S. Retirement Income Plan based on guidelines established by the Pension Benefit Guaranty Corporation. U.S. pension expense represents only the service cost related to the U.S. pension plan that is recorded within Operating Income. For all periods presented, we were not required and did not make cash contributions to our U.S. Retirement Income Plan. For the Year Ending December 31, 2020 Low to High Net (loss) $-96 to $-82 Add: Interest expense 25 25 Add: RIP Expense (1) 360 360 (Less): Income tax benefit -25 -29 Add: Net Environmental Expenses 1 1 (Less): Gain on Sale of Idled China Plant Facility -21 -21 Add: U.S. Pension expense (2) 6 6 Add: D&A 70 70 Adjusted EBITDA $320 to $330

Adjusted EPS & Free Cash Flow – Guidance Reconciliation Adjusted Diluted Earnings Per Share Adjusted Free Cash Flow Adjusted EPS guidance for 2020 is calculated based on an adjusted effective tax rate of 25% and based on ~48 million of diluted shares outstanding. RIP expense represents the actuarial net periodic benefit expected to be recorded as a component of other non-operating income. We do not expect to be required to make, nor do we plan to make cash contributions to our U.S. Retirement Income Plan based on guidelines established by the Pension Benefit Guaranty Corporation. RIP expense represents only the service cost related to the U.S. pension plan and is recorded as a component of operating income. We do not expect to be required to make, nor do we plan to make cash contributions to our U.S. Retirement Income Plan based on guidelines established by the Pension Benefit Guaranty Corporation. For the Year Ending December 31, 2020 Low to High Net cash provided by operating activities $195 to $205 Add: Return of investment from joint venture ($60-$65M) 60 65 Adjusted net cash provided by operating activities $255 to $270 (Less): Capital Expenditures ($55-$60M) -55 -60 Adjusted Free Cash Flow $200 to $210 For the Year Ending December 31, 2020 Low Per DilutedShare(1) to High Per DilutedShare(1) Net (loss) $-96 $-2 to $-82 $-1.71 low high Add: Interest expense 25 25 Add: RIP expense (2) 360 360 (Less): Income tax (benefit) -25 -29 Add: Net Environmental Expenses 1 1 (Less): Gain on Sale of Idled China Plant Facility -21 -21 Operating income 244 254 Add: RIP expense (3) 6 6 (Less): Interest expense -25 -25 Adjusted earnings before income taxes 225 to 235 (Less): Income tax expense -56 -59 rate 0.25 0.25 Adjusted net income $169 $3.5 to $176 $3.7 shares 48 48 $226.25 $4.6173469387755102 to $241.3 $4.924489795918368 $40 $40 $-20 $-20 $68.775000000000006 $73.775000000000006 $315.10000000000002 $335.1 $5 $5 $-40 $-40 $280.10000000000002 to $300.10000000000002 $-70.025000000000006 $-75.025000000000006 $210.07500000000002 $4.3765625000000004 to $225.07500000000002 $4.6890625000000004