Exhibit 99(A)(7)
 
  [LOGO]
   BIRD
CORPORATION
                                                                  April 12, 1996
 
Dear Stockholder:
 
  I am pleased to report that on April 8, 1996, Bird Corporation (the
"Company") entered into an amended and restated merger agreement (the "Merger
Agreement") with CertainTeed Corporation ("CertainTeed") and its wholly owned
subsidiary, BI Expansion Corp. (the "Purchaser"), that provides for the
acquisition of the Company by CertainTeed through the acquisition by the
Purchaser of all the outstanding shares of the common stock, $1 par value per
share, of the Company (the "Common Shares") and all the outstanding shares of
the $1.85 Cumulative Convertible Preference Stock, $1 par value per share, of
the Company (the "Preference Shares", and together with the Common Shares, the
"Shares"). Pursuant to the Merger Agreement, the Purchaser has today commenced
a cash tender offer (the "Offer") for all outstanding Common Shares and
Preference Shares at a price of $7.50 per Common Share and $20 plus all accrued
and unpaid dividends through the expiration date of the Offer per Preference
Share. The tender offer is currently scheduled to expire at 12:00 midnight, New
York City time, on Thursday, May 9, 1996.
 
  Following the successful completion of the Offer, upon approval by
stockholder vote, the Purchaser will be merged (the "Merger") with and into the
Company, and all Shares not purchased in the Offer will be converted into the
right to receive in cash $7.50 per Common Share and (unless the Preference
Shares have previously been redeemed) $20 plus all accrued and unpaid dividends
through the effective date of the Merger per Preference Share.
 
  YOUR BOARD OF DIRECTORS HAS UNANIMOUSLY APPROVED THE OFFER AND THE MERGER AND
DETERMINED THAT THE TERMS OF THE OFFER AND THE MERGER ARE FAIR TO AND IN THE
BEST INTERESTS OF THE COMPANY'S STOCKHOLDERS. ACCORDINGLY, THE BOARD OF
DIRECTORS UNANIMOUSLY RECOMMENDS THAT THE COMPANY'S STOCKHOLDERS ACCEPT THE
OFFER AND TENDER THEIR SHARES.
 
  In arriving at its recommendations, the Board of Directors gave consideration
to a number of factors. These factors included the opinion of Dillon, Read &
Co. Inc., financial advisor to the Company, that the consideration of $7.50 per
share in cash to be received by the holders of Common Shares pursuant to the
Offer and the Merger is fair to such holders from a financial point of view.
All of the factors considered by the Board of Directors are more fully
described in the Solicitation/Recommendation Statement on Schedule 14D-9 filed
by the Company with the Securities and Exchange Commission and enclosed with
this letter. We urge you to read carefully the Schedule 14D-9 in its entirety
so that you will be fully informed as to the Board's recommendations.
 
  Also accompanying this letter is a copy of CertainTeed's and the Purchaser's
Offer to Purchase and related materials, including a Letter of Transmittal for
use in tendering Shares. These documents set forth the terms and conditions of
the Offer and provide instructions as to how to tender your Shares. We urge you
to read each of the enclosed materials carefully.
 
  The Board of Directors and management of the Company thank you for the
support you have given the Company.
 
  On behalf of the Board of Directors,
 
                                          Sincerely,
 
                                          /s/ Joseph D. Vecchiolla

                                          Joseph D. Vecchiolla
                                          Chairman of the Board of Directors