VALLEY FORGE, Pa.
Peter Dachowski, President and CEO of CertainTeed Corporation, says the
team sponsorship is a great way to connect with customers. The effects of USG's
Chapter 11 reorganization and the conduct, outcome and costs of the Chapter 11
cases, including the ultimate outcome and costs associated with the
Corporation 's agreement to resolve asbestos liabilities, may differ from
management's expectations.

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8 billion in 2005.

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However, the company's Board of
Directors has the power to accelerate or extend the expiration date of the
rights.
USG Corporation is a Fortune 500 company with subsidiaries that are market
leaders in their key product groups: gypsum wallboard, joint compound and
related gypsum products; cement board; gypsum fiber panels; ceiling panels and
grid; and building products distribution.

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Under the new shareholder rights plan, if any person
acquires beneficial ownership of 5 percent or more of USG's voting stock,
shareholders other than the 5 percent triggering shareholder will have the
right to purchase additional USG common stock at half their market price,
thereby diluting the triggering shareholder.

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, CertainTeed Corporation, one of
North America's leading building products manufacturers, is proud to announce
a partnership with sister companies Norton Abrasives and BPB in a team
sponsorship of the number 66 Best Buy Chevrolet for the 2006 NASCAR Nextel Cup
Season. Today, CertainTeed is a leading North American manufacturer of
residential and commercial roofing; vinyl and fiber cement siding; vinyl and
composite fence, railing and decking; vinyl windows; residential, commercial
and mechanical insulation; pipe and foundations; and access covers. USG shareholders who already own
5 percent or more of USG's common stock as of January 30, 2006, including
Berkshire Hathaway Inc.

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com/cgi-bin/prnh/20010511/USGLOGO )
As announced on January 30, 2006 , USG adopted a Reorganization Rights
Plan, commonly referred to as a "poison pill.

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"NASCAR offers CertainTeed, Norton Abrasives and BPB fantastic brand
exposure in a sport known for its intense, brand-loyal fan base," says
Dachowski. CHICAGO, USG Corporation (NYSE: USG), in
response to an inaccurate news report, said today that it has not declared a
cash dividend with respect to its common stock.

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The Haas/CNC Racing team is based in Harrisburg, North Carolina, and has
recently broken ground on a state-of-the-art 140,000 square foot auto shop in
Kannapolis, North Carolina, where Green and his wife reside. Actual business, market or other conditions may
also differ from management's expectations and accordingly affect the
corporation's sales and profitability or other results.

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The Norton Abrasives brand of Saint-Gobain Abrasives is the world's
largest manufacturer and supplier of performance abrasives.newscom. For more information about USG
Corporation, visit the USG home page at http://www.

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Norton Abrasives and BPB are also featured on
the car.

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One of the top 100
industrial companies in the world, Saint-Gobain's 2005 sales were
approximately $44 billion .

USG Corrects Inaccurate News Report

" These plans are accomplished
by declaring a dividend of preferred stock purchase rights that, until certain
triggering events occur, attach to and cannot be traded separately from the
company's common stock. In addition, the USG Board of Directors has the right, before or after
the rights plan expires, to take such other actions that it determines in the
exercise of its fiduciary duties to be necessary in the future, which could
include the adoption of a new shareholder rights plan or further amendments of
the existing plans.

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Saint-Gobain is a leading producer of construction products
(building materials, insulation and pipe), high-performance materials
(abrasives, industrial ceramics, high-performance plastics, and
reinforcements), flat glass, and glass containers.

The new rights plan will expire on December 31, 2006 or, if later, 30 days
after the effectiveness of the plan of reorganization if the FAIR Act has not
passed in the current session of Congress.
This press release does not constitute an offer of any securities for sale
in the rights offering.

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certainteed.com
CertainTeed, Norton Abrasives , and BPB are subsidiaries of Saint-Gobain of
Paris, France. USG
Corporation assumes no obligation to update any forward-looking information
contained in this press release.

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I am thrilled that BPB
and Norton Abrasives are part of our team.
Founded in 1904 as General Roofing Company, the firm made its slogan "Quality
Made Certain, Satisfaction Guaranteed," which quickly inspired the name
CertainTeed.
Headquartered in Valley Forge, Pennsylvania, CertainTeed employs
approximately 7,000 employees and 40 manufacturing facilities throughout the
U.

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(Logo: http://www.

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CertainTeed had sales of $2.

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"This marks the
sixth year CertainTeed has been part of the one of the largest spectator
sports in America. NASCAR has been an excellent vehicle for doing business
with building professionals who look forward to attending races, meeting
drivers, and interacting with CertainTeed each year .S.

The focus is on the processing of building materials, the manufacture of end products and building components, and the tools used by installers and tradespeople.

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In addition,
CertainTeed has prime positioning on the number 66 car with logo placement
above the rear quarter panel. The company is also a
leading distributor of building products in Europe.

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, will not trigger these rights so long as they do not
increase their percentage ownership of USG common stock by more than an
additional 1 percent while the plan is in effect, other than pursuant to
proportional participation in the $1. Actual results may
differ due to various other factors, including economic conditions such as the
levels of construction activity, employment levels, interest rates, currency
exchange rates and consumer confidence; competitive conditions such as price
and product competition; shortages in raw materials; increases in raw material
and energy and employee benefit costs; loss of one or more customers; the
unpredictable effects of acts of terrorism or war upon domestic and
international economies and financial markets; and acts of God.

This category indexes sites dealing with equipment and supplies used in the building and construction trades.

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BPB, which was
recently acquired by CertainTeed 's parent company Saint-Gobain of Paris,
France, is the world leader in gypsum wallboard and a leading supplier of
ceiling tiles and finishing products.

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The car, driven by 2000 NASCAR Busch Series champion Jeff Green is
owned by Haas/CNC Racing.com .

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CertainTeed Partners With Sister Companies in Team Sponsorship of Haas/CNC NASCAR Nextel Cup Team for 2006

8 billion common stock rights offering
also announced by USG on January 30, 2006 to provide funding to finance a
portion of the payments in its proposed plan to emerge from Chapter 11
proceedings.

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"
As part of the sponsorship, CertainTeed will host 15 race-day hospitality
events at which Green will be on deck to sign autographs and talk with invited
guests of the company, as well as Norton Abrasives and BPB.

About CertainTeed Corporation
Through innovation and creative product design, CertainTeed Corporation
has helped shape the building products industry for more than 100 years.

This press release contains forward-looking statements related to
management's expectations about future conditions.

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fenestration wallbank

http: //www.usg.