Strong First-Quarter Earnings Growth

Positions Company for Success in 2013

Sell-Side Analyst Meeting May 2, 2013 – Amarillo, TX

Michael McMurray Chief Financial Officer

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Forward-Looking Statements and Non-GAAP Measures

This presentation consists of this slide deck and the associated remarks and comments, all of which are integrally related and are intended to be presented and understood together.

This presentation contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Forward-looking statements are any statements that are not historical facts, and they are based upon the Company’s current expectations. Because forward-looking statements involve risks and uncertainties, the Company’s actual results could differ materially from those projected in these statements. Information regarding some of the risks and uncertainties that could cause such differences can be found in the Company’s Securities and Exchange Commission (“SEC”) filings, including under Item 1A of the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2012.

For purposes of this presentation, any discussion referring to “year to date” refers to the period ended December 31, 2012. Otherwise the information in this presentation speaks as of May 2, 2013, and is subject to change. The Company does not undertake any duty to update or revise forward-looking statements. Any distribution of this presentation after May 2, 2013 is not intended and will not be construed as updating or confirming such information.

This presentation contains references to certain "non-GAAP financial measures" as defined by the SEC. A reconciliation of these non-GAAP financial measures to their most directly comparable financial measures calculated and presented in accordance with generally accepted accounting principles can be found in our Current Report on Form 8-K furnished to the SEC on April 24, 2013. This Form 8-K and additional Company information is available on the Owens Corning website: www.owenscorning.com. Adjusted EBIT is earnings before interest, taxes, and other items that management does not allocate to our segment results because it believes they are not a result of the Company’s current operations.

THE PINK PANTHER™ © 1964-2012 Metro-Goldwyn-Mayer Studios Inc. All Rights Reserved. The color PINK is a registered trademark of Owens Corning. © 2012 Owens Corning.

Q1 2013 Outlook and Highlights

Continued to focus on building a safer workplace

Improved adjusted EBIT by $34 million

Grew Roofing EBIT margins from 14% to 20% on effective price execution

Insulation on track for profitability in 2013

Composites completes asset ramp-up; on track to achieve positive operating leverage for remainder of 2013

Strong first-quarter performance supports full-year outlook of at least $100 million improvement in adjusted EBIT with potential upside

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Expect margin performance improvement in each business

Expect adjusted EBIT to grow at least $100 million with potential upside

The upside to the outlook will largely be determined by the pace of the U.S. housing recovery and its impact on Building Materials margins

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2013 Guidance

Owens Corning Composites Positioned for Improved Returns

Sell-Side Analyst Meeting May 2, 2013 – Amarillo, TX

Arnaud Genis President Composites Business

Macro Trends Support Glass Fiber Market Growth

Favorable Economic Trends

6 Sources: 1 .Oxford Economics, 2 .IHS CSM Automotive, 3. MAKE, 4.Feb 2013 Blue Chip Consensus, 5 .IHS Global insight – Relevant Industrial Capex defined as oil & gas, mining

and water supply industries only , 6 . Owens Corning management estimates as of Apr 2013

Economic Indicators 2012 2013F 2014F Supporting Trends

Global Industrial Production

Growth Rate *1

1.7% 2.6% 4.3% Growth recovery

Automotive Builds (mm) *2 81 83 88 8 kg of glass fiber used per

vehicle (and growing) *6

Wind Installations (GW) *3 47 45 50 U.S. Production Tax Credit

extended; 7.5 kT glass fiber per

GW *6

North America Housing Starts

(mm) *4

0.8 1.0 1.2 100 kg glass fiber used per

housing unit on average *6

Relevant Industrial Capex ($B) *5 625 660 700 Rising costs for steel and

aluminum

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10

1981 1991 2001 2011

Gla

ss

Fib

er

De

ma

nd

(M

M T

on

s)

- lo

g b

as

is

Glass Fiber Market Outlook

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Glass Fiber Market Demand 30 Years Averaging 5% CAGR

2013-2016 Growth Forecast

2017

Glass Fiber Market Expected to

Continue to Grow at Historical Rates

About 60% of Growth

Expected to Come from China

Glass fiber market demand excludes E-glass yarns

Sources: Fiber economic bureau, Glass Fiber Europe, Global Trade information Services, inc. and Owens Corning management estimates as of Apr 2013

Annual Market Growth Expected to Absorb the Equivalent of Three

to Four World-Scale Plants on Average in 2013-2016 Timeframe

-

250

500

750

China Americas EMEA Rest of Asia India

Dem

an

d G

row

th (

k t

on

s)

Composites Materials Price History

Market Price of Composites

vs. Traditional Materials

8 Sources: Composite represents a combination of textile glass fiber and thermoset resins. Textile glass fiber, thermoset resin, steel and aluminum US Bureau of Labor Statistics

Composites Materials Have Become More Competitive

60

80

100

120

140

160

180

200

220

1992 1997 2002 2007 2012

Ind

ex

(19

92

=1

00

)

Composite Materials Steel Aluminum

Cost Trends

North

America Europe China

Energy

Labor

Materials

Logistics

Foreign

Exchange

Cost Trends Favor a Global Network

Color coding indicates relative rate of growth compared to other regions. Cost drivers measured in their respective functional currency .

Sources: IHS Global Insight 2012-2015 projections, Owens Corning management estimates as of Apr 2013

China Facing Higher Inflation and Currency Appreciation

9

0.5

1.1 1.1

1.7

0.3

0.5

2005-09 2010-12 2013-16 Change in global demand (MM T) Change in global capacity (MM T)

0.1 / yr 0.3 / yr 0.4 / yr 0.1 / yr 0.3 / yr 0.1 / yr

50%

60%

70%

80%

90%

100%

110%

Es

tim

ate

d C

ap

ac

ity U

tili

za

tio

n

Glass Fiber Industry Capacity

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Glass Fiber Industry Estimated Capacity Utilization

Tighter Capacity Environment

Glass fiber market demand excludes E-glass yarns

Sources: Fiber economic bureau, Glass Fiber Europe, Global Trade information Services, inc. and Owens Corning management estimates as of Apr 2013

Supply Tension

Over 20% of global capacity will need to be rebuilt in China between 2013 and 2016

Owens Corning does not expect to add incremental melting capacity before 2015

(high probability

additions)

2004 2006 2008 2010 2012 2014 2016

Chinese Emergence

Capacity Overbuild

Macro Adjustment

Excess Inventory

Supply Tension

Return on Capital

Glass Fiber Industry Phases Signs of a New Era

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High Utilization Rates and Reinvestment Economics Support Higher Returns

2005 – 2009 2010 – 2012 2013 – 2016

The glass fiber market is healthy and will grow driven by improving economic conditions and continuing material conversion

Glass fiber reinvestment economics in China are changing, as costs increase, currency appreciates, and furnaces require rebuilding

Composites materials remain a great value vs. other materials

Our focus is on offsetting inflation and returning margins to levels that support investment

Owens Corning Composites Positioned for Improved Returns

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