FOCUSED ON SHAREHOLDER VALUE

E

Q4 2019This presentation shared at the following events:

12/02/19 OC Roadshow Scott Cripps, Vice President, Investor Relations

11/04/19 OC Roadshow Hosted by Wells Fargo – Texas Brian Chambers, Chief Executive Officer

10/31/19 OC Roadshow Hosted by Zelman – Boston Brian Chambers, Chief Executive Officer

10/29/19 OC Roadshow Hosted by Northcoast – St. Louis Gunner Smith, President, Roofing

FORWARD-LOOKING STATEMENTS AND NON-GAAP MEASURESThis presentation and the associated remarks contain forward-looking statements. We caution you against relying on these statements as they involve risks and uncertainties that are difficult to predict and the Company’s actual results may differ materially from those projected. Such risks and uncertainties include, without limitation: macroeconomic factors like levels of construction activity, global industrial production, and industry, economic and political conditions, including new legislation, policies or other governmental actions in the U.S. or elsewhere; relationships with key customers and demand for our products; competitive and pricing factors; changes to tariff, trade or investment policies or law; currency, commodity and interest rate fluctuations; our level of indebtedness and the availability and cost of credit; weather conditions; ability to protect our intellectual property and information technology systems; energy, transportation, raw material and other input availability, price volatility and cost issues; labor disputes, legal and regulatory proceedings; ability to utilize our net operating loss carry-forwards; uninsured losses; issues related to acquisitions, divestitures and joint ventures; achievement of expected synergies or productivity improvements; levels of goodwill or other indefinite-lived intangible assets; pension obligations; and factors detailed from time to time in the Company’s SEC filings.

The terms “year to date” or last twelve months (“LTM”) refer to the period ended on the last calendar day of the quarter preceding the date of the investor event referenced on the first page above. Otherwise the information in this presentation speaks as of the date of the investor event, and is subject to change. The Company assumes no obligation to update or revise forward-looking statements except as required by law. Any distribution of this presentation after the investor event is not intended and should not be construed as updating or confirming such information.

This presentation contains references to certain "non-GAAP financial measures" as defined by the SEC, which may be referenced in the Appendix. Adjusted EBIT, adjusted EBITDA, adjusted earnings, adjusted EPS and return on capital exclude certain items that management does not allocate to its segment results because it believes they are not representative of the Company’s ongoing operations. When the company provides forward-looking expectations for non-GAAP measures, the most comparable GAAP measures and reconciliations to those GAAPmeasures are generally not available without unreasonable effort due to the variability, complexity and limited visibility of the adjusting items that would be excluded from the non-GAAP measures in future periods. The variability in timing and amount of adjusting items could have significant and unpredictable effects on future GAAP results.

2THE PINK PANTHER™ & © 1964-2019 Metro-Goldwyn-Mayer Studios Inc. All Rights Reserved. © 2019 Owens Corning. All Rights Reserved.

AGENDA

Investment highlights

Three strong businesses

Additional financial information

3

1

2

3

2018 REVENUE COUNTRIES WHERE WE OPERATE

CONSECUTIVE YEARS AS A FORTUNE® 500

COMPANY

OWENS CORNING AT A GLANCE

4

EMPLOYEES

20,000

INSULATION | ROOFING | COMPOSITES

Serving residential, commercial, and industrial markets

DISCIPLINED CAPITAL ALLOCATION

MARKET-LEADING POSITIONS STRONG CASH FLOW GENERATION

INNOVATIVE PRODUCT &PROCESS TECHNOLOGIES

5

We are a global building and industrial materials leader that capitalizes on market-leading positions and innovative technologies to deliver substantial free cash flow and sustainable shareholder value

COMPELLING INVESTMENT THESIS

7%

82%

6%

5%

27%

10%

23%

40%

1%

12%

29%58%

33%

13%

33%

34%

17%

19%

17%

34%

2006 2018

GLOBAL BUSINESSES IN ATTRACTIVE END MARKETSOwens Corning

revenue by end market

U.S. residential new construction

Consolidated figures eliminate intercompany net sales between reportable segments. Source: Owens Corning management estimates; estimated error margin +/- 5%. In the residential markets, certain products are used interchangeably in both new construction and repair and remodeling, and our customers typically sell into both markets. Due to these limitations, we have used management estimates and other assumptions to allocate residential market net sales

InternationalU.S. commercial and industrial

U.S residential repair and remodeling

6

2018 revenue by end market

$5.4B $7.1BRoofing CompositesInsulation

Accelerate organic growth

PURPOSEFUL ACTIONS HAVE RESULTED IN SUSTAINABLE IMPROVEMENT

Adjusted EBIT margin

2013 - 2015

13%9%7%

2006 - 2012

2016 - 2018

Management actions Enterprise improvement

7

Operating priorities

Implemented sustainable cost reductions across businesses

Invested in process and product technologies to fuel organic growth

Completed acquisitions delivering profitable growth and more stable earnings

Drive improved operating efficiencies

Generate strong freecash flow

INVESTMENT HIGHLIGHTS

OWENS CORNING $7,057 $861 12%2018 NET SALES 2018 ADJ EBIT 2018 ADJ EBITAS % OF NET SALES

#1 in North American residential fiberglass

A leader in technical insulation growth markets

$2,720 $290 11%

#2 in attractive industry generating strong operating margins

High margin Components business provides growth upside

$2,492 $434 17%

#1 in glass non-wovens

#2 in global glass fiber market$2,041 $251 12%

9

THREE MARKET-LEADING BUSINESSES

Roofing

Insulation

Composites

10

WELL-POSITIONED TO CAPTURE GROWTH FROM KEY SECULAR TRENDS

ENERGY EFFICIENCY PRODUCT SAFETY & SUSTAINABILITY

RENEWABLE ENERGY RISING LABOR COSTS & WORKER SHORTAGE

INVESTMENT IN INFRASTRUCTURE

Building code compliant

Fire resistant Wind turbines Roads, bridgesEasy and efficient

installation

Full temperature range solutions

Recyclable Solar homesPipes / water management

Pre-fabricated construction

INNOVATIVE PRODUCT & PROCESS TECHNOLOGIES DELIVERING REVENUE GROWTH, IMPROVED MARGINS, AND CAPITAL EFFICIENCY

11

Unique SureNail®

technologyIndustry-leading product designs

Glass material science

Sustainable high margins

Highly-specified applications

Advantaged costposition

DURATION®SHINGLES

SPECIALTY GLASS NON-WOVENS

ECOTOUCH®INSULATION

12

LEVERAGING ENTERPRISE CAPABILITIES

Global footprint and scale

Commercial strength

Material science innovation

Manufacturing technologies

ROOFING

INSULATION

COMPOSITES

Safety and sustainability

FREE CASH FLOW CONVERSION OUTPERFORMS PEER GROUP

Free cash flow conversion defined as (cash flow from operating activities – capital expenditures)/(adjusted earnings)Source: management estimates

0%

25%

50%

75%

100%

125%

Average 2016-18 free cash flow conversion

Owens CorningDow Jones U.S. Construction & Materials Index

13

EBIT margin improvement

Purposeful working capital management

Focused on operating and capital efficiency

FOCUSED ON KEY DRIVERS OF SHAREHOLDER VALUE CREATION

Source: SEC filings, please refer to Appendix for reconciliation to Owens Corning SEC filings.

Return on capital

Adjusted EBIT marginRevenue growth

14

7.2%

9.3%

11.9% 12.2%

10.2%

2014 2015 2016 2017 2018

-0.7%

1.7%

6.1%

12.5%

10.5%

2014 2015 2016 2017 2018

7.8%

10.3%

13.1% 13.4%12.2%

2014 2015 2016 2017 2018

Free cash flow ($mm)

Free cash flow conversion: 103%

$50

$341

$570

$679

$266

2014 2015 2016 2017 2018

CAPITAL ALLOCATION STRATEGY FOCUSES ON INCREASING TSR2016-2018: RETURNED OVER $900MM OF CASH TO SHAREHOLDERS

Cash to shareholders reflects dividends paid plus share repurchases of outstanding common stock. Source: Owens Corning SEC filings. 15

Maintain investment grade balance sheet

with flexibility to support growth and drive shareholder value

Maintain safe, sustainable, and productive operations

in our existing business

Invest in targeted growth opportunities

organic growth and bolt-on acquisitions

Capital allocation strategy Capital allocation targets over time

Return excess cash to shareholders

through dividends and share repurchases

2-3X debt/EBITDA leverage

Deploy capital in line with D&A with a focus on productivity and organic growth investments

Return at least 50% of free cash flow to shareholders

SIGNIFICANT RECOGNITION FOR ESG LEADERSHIP

Ranked #1 seven years consecutively in the Building Products Group (top scores in environmental, social and economic for 3rd year in a row)

Earned “Gold Class” score in 2019 for the 6th consecutive year

Obtained a perfect score on 2019 Corporate Equality Index for the 15th time

Ranked 1st among 100 Best Corporate Citizens in 2019

Included in CDP’s “A List” for climate change, water and supply chain in 2017-2018

Recognized by Ethisphere as 1 of only 4 honorees in the Construction and Building Materials Industry

Earned the following ISS scores in 2019:• Environmental: 1• Social: 1 • Governance: 2

Note: recognitions and rankings as of September 2019 16

First company in the U.S. industrials sector to issue a green bond

THREE STRONG BUSINESSES

18

INSULATION BUSINESS

Source: Owens Corning management estimates and Owens Corning SEC filings; comparability may differ over time. Revenue before inter-segment eliminations.

Five-year financial performance

EBIT as % of net salesNet sales in millions

Leverage broad portfolio in commercial and industrial markets around the world

U.S. residential construction macro environment below historical averages

Drive competitive advantage through operational and commercial technology

0%

2%

4%

6%

8%

10%

12%

$0

$500

$1,000

$1,500

$2,000

$2,500

$3,000

2015 2016 2017 2018 LTM

BUILT A STRONGER GLOBAL INSULATION BUSINESS

NORTH AMERICA EUROPE CHINA

HIGH

MID

LOW

TE

MP

ER

AT

UR

E R

AN

GE

PAROC® is a registered trademark for mineral wool insulation 19

EXPANDED TECHNICAL AND OTHER BUILDING INSULATION TO DELIVER MORE STABLE AND ATTRACTIVE MARGINS

Insulation delivered 19% average EBITDA margin over the period 1985-2008

Acquisitions in technical insulation have grown and strengthened the business with attractive and stable margins

Investments in productivity and process technology enabling network optimization and a lower cost footprint

North American residential fiberglass insulation includes batts & rolls and loosefill sold to insulation contractors and distributors, home centers, and manufactured housing producers in the U.S. and Canada. Technical and other building insulation includes pipe and flexible duct media insulation, cellular glass insulation, foam, mineral fiber, and all building material products sold to Europe, Latin America and Asia. Comparability may differ over time. Margin of error on intra-segment EBITDA estimated to be below $15MM. Source: Historical data based on Owens Corning management estimates. Please refer to appendix for reconciliation to Owens Corning SEC filings. Competitive information based on legally obtained information from third parties and public sources.

(100)

0

100

200

300

400

2006(Peak)

2009(Trough)

2018E

BIT

DA

($

mm

)

North American residential fiberglass insulation

Technical and other building insulation

Insulation EBITDA and margins

% of net sales

30% 22% (11%) 13% 18% 17%

20

21

ROOFING BUSINESS

Source: Owens Corning management estimates and Owens Corning SEC filings; comparability may differ over time. Revenue before inter-segment eliminations.

EBIT as % of net salesNet sales in millions

Track record of strong operating performance

Positive outlook based on product preference and market drivers

Components business growing above market with attractive margins

Commercial & operational performance driving sustainable earnings

Five-year financial performance

0%

5%

10%

15%

20%

25%

$0

$600

$1,200

$1,800

$2,400

$3,000

2015 2016 2017 2018 LTM

POSITIVE OUTLOOK FOR U.S. ASPHALT ROOFING DEMAND

+ + =

Housing activity below long term averages provides growth opportunity

Aging housing stock

Economic factors: existing home sales, home equity, consumer income

~40mm square average storm market in last 10 years

Weather events drive early replacement of roofs

Source: Owens Corning management estimates based on data from Principia Partners Roofing Data and RS Means – average roof size of 30 squares 22

Remodeling New constructionMajor storms & weather events

REMODELING & NEW CONSTRUCTION MARKETS HAVE BEEN GROWING

26 17 11 11 11 14 17 18 19 20 21 22

7573

71 63 61 59 5860 65

68 7477

2523

21 28 31 34 30 2324

3034 24

3 2217

619 11 6 6

4

1515

13

2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

New construction Remodeling Weather events Major storms

U.S. asphalt shingle market in mm squares

Total 129 135 120 108 122 118 111 107 112 133 144 136

Source: Owens Corning management estimates based on data provided by Asphalt Roofing Manufacturers Association - Summary of Asphalt Roofing Industry Shipments, National Oceanic and Atmospheric Administration, National Association of Realtors, U.S. Energy Information Administration, Moody’s Analytics, Oxford Economics reports, U.S. Bureau of Labor Statistics and U.S. Bureau of Economic Analysis 23

24

COMPOSITES BUSINESS

Source: Owens Corning management estimates and Owens Corning SEC filings; comparability may differ over time. Revenue before inter-segment eliminations.

EBIT as % of net salesNet sales in millions

Continued global growth

Favorable industry trends

Well-positioned to leverage market growth with a capital-efficient strategy

Glass non-wovens is an attractive business with strong reinvestment economics

Five-year financial performance

0%

3%

6%

9%

12%

15%

$0

$500

$1,000

$1,500

$2,000

$2,500

2015 2016 2017 2018 LTM

GLASS FIBER – AN $8B MARKET WITH FAVORABLE EXPOSUREMarkets

Size

Building & Construction

Transportation Consumer Industrial Power & Energy

Glass fiber market defined as glass fiber reinforcements and direct conversion products as consumed, excluding yarns. Sources: Fiber Economics Bureau, GlassFibreEurope (APFE), Global Trade Information Services, Inc. and Owens Corning management estimates as of January 2019. 25

% Market Revenue = market revenue in region as % of 2018 global market size; % OC Revenue = OC revenue in region as % of OC Composites global 2018 net sales; Glass reinforcements market defined as glass fiber reinforcements and direct conversion products as consumed, excluding yarns. Sources: Fiber Economics Bureau, GlassFibreEurope (APFE), Global Trade Information Services, Inc. and Owens Corning management estimates of 2018 global market.

POSITIONED TO COMPETE ANYWHERE IN THE WORLD

Glass Non-Wovens

Glass Reinforcements

33%

48%

% MarketRevenue

% OCRevenue

Americas

#1 Position

23% 29%

% MarketRevenue

% OCRevenue

EuropeEmerging position

#1 Position

18%13%

% MarketRevenue

% OCRevenue

Rest of world

26

26%

10%

% MarketRevenue

% OCRevenue

China

#1 Position

ADDITIONAL FINANCIAL INFORMATION

APPENDIX A: KEY FINANCIAL DATA – CORPORATE

Source: Owens Corning SEC filings; reportable segment totals are shown in SEC filings before intercompany eliminations, please refer to Appendix for reconciliation to Owens Corning SEC filings. 28

($ in millions, except per share data) Q3 2019 Q3 2018 YTD 2019 YTD 2018

Net sales 1,883 1,818 5,468 5,333

Net earnings attributable to Owens Corning 150 161 332 374

Diluted earnings per share (EPS) attributable to Owens Corning common stockholders

$1.36 $1.45 $3.02 $3.35

Earnings before interest and taxes (EBIT) 277 259 625 596

Earnings before interest, taxes, depreciation and amortization (EBITDA) 389 366 962 919

Adjusted EBIT 277 267 624 633

Adjusted EBITDA 389 373 961 947

Adjusted earnings 179 174 382 398

Adjusted EPS (diluted) $1.63 $1.57 $3.47 $3.56

Adjusted EBIT as a % of net sales 15% 15% 11% 12%

Adjusted EBITDA as a % of net sales 21% 21% 18% 18%

Depreciation and amortization (D&A) 112 107 337 323

Net cash flow provided by operating activities 309 200 596 506

Free cash flow 208 79 282 81

Net debt 3,155 3,533 3,155 3,533

APPENDIX A: KEY FINANCIAL DATA – BUSINESS

Source: Owens Corning SEC filings; reportable segment totals are shown in SEC filings before intercompany eliminations

Insulation Roofing Composites

($ in millions) Q3 2019 Q3 2018 Q3 2019 Q3 2018 Q3 2019 Q3 2018

Net sales 693 710 713 645 531 508

EBIT 84 94 143 127 67 64

EBIT as % of net sales 12% 13% 20% 20% 13% 13%

D&A 48 47 14 13 37 36

29

($ in millions) YTD 2019 YTD 2018 YTD 2019 YTD 2018 YTD 2019 YTD 2018

Net sales 1,945 1,988 2,105 1,946 1,579 1,560

EBIT 141 175 368 351 191 195

EBIT as % of net sales 7% 9% 17% 18% 12% 12%

D&A 146 138 40 38 114 109

APPENDIX A: 2019 OUTLOOK

Environment consistent with consensus global industrial production growth, U.S. housing starts, and global commercial and industrial construction growth

Macro environment

Business outlook

• Strong cash flow generation

• Prioritize free cash flow to dividends & reduction of term

loan

• Additionally, free cash flow could be available for share

repurchases

• Corporate expenses: $110mm-$115mm

• Interest expense: approximately $130mm

• Capital expenditures: approximately $460mm, in-line

with D&A

• Depreciation & amortization: about $460mm

• Cash tax rate of: 9-11% and book tax rate of 26-28% on

adjusted pre-tax earnings

Other guidance items

Source: Owens Corning management estimates 30

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 1

31

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 2

32

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 3

33

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 4

34

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 5

35

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 6

36

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 7

37

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 8

38

APPENDIX B: NON-GAAP RECONCILIATION – TABLE 9

39