[Date]

TO EACH HOLDER OF OPTIONS
TO PURCHASE SHARES OF SERIES
A PREFERRED STOCK OF BUILDING
MATERIALS CORPORATION OF AMERICA

Dear Optionee:

     Reference is made to the Option Agreement dated September 13, 1996, as
previously amended by amendment dated June 27, 1997 (the "Agreement"), pursuant
to which you were granted an option to purchase shares of Series A Cumulative
Redeemable Convertible Preferred Stock of Building Materials Corporation of
America.

     The Agreement is hereby amended as follows:

     1. The first sentence of Section 1(b) of the Agreement is hereby amended to
read in its entirety as follows:

     "The Option shall vest and become exercisable as to 20% of the
     Preferred Shares on December 31 in each of the years 1996 through
     2000, in each case to the extent you are employed by the Company or
     its subsidiaries on such date; provided that (i) if your employment
     with the Company and its subsidiaries should terminate as a direct
     result of a divestiture (whether because you are employed by the
     business which is sold, your position is eliminated as a result of the
     divestiture or otherwise) or (ii) if, after a Change of Control of the
     Company, your employment with the Company and its subsidiaries (x)
     should be terminated by the Company other than for cause, (y) is
     terminated as a result of your death or permanent disability, or (z)
     is terminated by you for "good reason", the unvested portion of the
     Option shall become vested on the date of your termination. You shall
     be deemed to terminate your employment for "good reason" if you do so
     as a result of a change or changes in the terms of your employment
     that are materially adverse to you, including with respect to your
     salary and bonus, level of responsibility or geographic location of
     employment."

<PAGE>


     2. The first sentence of Section 1(c) of the Agreement is hereby amended to
read in its entirety as follows:

     "The Option will terminate on the earliest of (i) December 31, 2004,
     (ii) 30 days after the termination of your employment with the Company
     and its subsidiaries for any reason other than your death or permanent
     disability or (iii) one year after the termination of your employment
     with the Company and its subsidiaries as a result of your death or
     permanent disability."

     3. Section 1(d) of the Agreement is hereby amended to read in its entirety
as follows:

     "Notwithstanding anything to the contrary contained in this Agreement,
     in the event the Company or its parent engages in a public offering of
     the common stock of the Company (an "IPO"), (i) you will be entitled
     to receive from the Company, on each vesting date set forth in Section
     1(b) (or, within five days after consummation of the IPO, in the case
     of the unexercised portion, if any, of the Option which is vested as
     of the date of consummation of the IPO), an amount in cash equal to
     the amount by which Book Value (as defined in Section 3(c)) of the
     Common Shares issuable upon conversion of the Preferred Shares subject
     to the portion of the Option which vests (or, in the case described in
     the immediately preceding parenthetical, is vested) on such date,
     determined as of the end of the calendar quarter immediately preceding
     the consummation of the IPO, exceeds the aggregate exercise price of
     such portion of the Option, and (ii) the Company will endeavor to
     grant you options to purchase shares of the Company's Common Stock
     which, together with the rights to receive cash described in clause
     (i) above, provide equivalent economic value to the Options granted to
     you pursuant to this Agreement that are unexercised as of the date of
     consummation of the IPO. Such new stock options will vest on the
     vesting schedule provided in Section 1(b) of this Agreement and will
     be granted under a stock option plan which is appropriate, in the
     judgment of the Board of Directors of the Company, for a public
     company. Your right to receive cash, and to exercise such new stock
     options, will be subject to the conditions to vesting set forth in
     Section 1(b), including the proviso to the first sentence thereof.
     Following consummation of the IPO, this Agreement (other than Section
     3(d) and this Section 1(d)) shall have no further force and effect."

     4. The first two sentences of Section 3(c) of the Agreement are hereby
amended to read in its entirety as follows, and a comparable change shall be
made to the first sentence of the definition of Book Value contained in Section
2(f) of the Certificate of Designation:

          "For purposes of this Agreement, 'Book Value' shall mean, as of
     any date of determination, (x) the sum of (i) the combined
     shareholder's equity


                                     2
<PAGE>


     of the Company and U.S. Intec, Inc. as of December 31, 1995 determined
     in accordance with generally accepted accounting principles, (ii) the
     cumulative consolidated net income or loss of the Company (treating
     U.S. Intec Holdings Inc. as a wholly-owned subsidiary of the Company
     for all periods) for the period January 1, 1996 through the date of
     determination and (iii) the cumulative operating income (or loss), net
     of an amount equal to imputed income taxes on such operating income
     calculated at the same tax rate as is accrued as an expense by the
     Company in its income statement for the applicable period, of GAF
     Fiberglass Corporation ("GAF Fiberglass") for the period January 1,
     1997 through the date of determination, and adding back (A) the charge
     to shareholder's equity relating to the assumption by the Company of
     certain asbestos-related liabilities of GAF Building Materials
     Corporation in connection with the Company's formation and (B) the
     reduction in shareholder's equity resulting from purchases of the
     capital stock of GAF Corporation ("GAF") by persons who participated
     in promoting the management buy-out of GAF in March 1989 (the
     "Acquisition") (predecessor cost basis adjustment), and excluding, to
     the extent occurring after December 31, 1995, (1) nonrecurring
     non-operating losses and nonrecurring non-operating gains, including
     any further charge relating to asbestos-related liabilities, (2) net
     gains or losses in respect of dispositions of assets by the Company
     other than in the ordinary course of business, (3) any dividends or
     distributions paid to the holders of the Company's capital stock, (4)
     any capital contributions made to the Company by its stockholders, (5)
     any amounts received by the Company for shares of its capital stock
     (including from the exercise of options or warrants to purchase
     capital stock or from the conversion into capital stock of convertible
     debt or convertible preferred stock) and (6) any charges relating to
     amortization of goodwill and other intangibles arising from the
     Acquisition divided by (y) 1,000,010. There shall be deducted from
     Book Value an amount equal to a 15% per annum charge on the aggregate
     capital contributions made to the Company by its stockholders during
     the period commencing October 1, 1997 and ending with the date of
     determination (the "Period"), amounts received by the Company during
     the Period for shares of its capital stock and, to the extent not
     actually charged to the Company, on the outstanding principal amount
     of loans and other advances made to the Company by affiliates
     (excluding subsidiaries of the Company) during the Period. There shall
     be added to Book Value a 15% per annum credit on the aggregate
     dividends or distributions made by the Company to its stockholders
     during the Period and, to the extent not actually charged to the
     borrower, on the outstanding principal amount of loans and other
     advances made by the Company to affiliates (excluding subsidiaries of
     the Company) during the Period. Any adjustments to Book Value
     (including the 15% charge and credit referred to in the preceding two
     sentences) shall include the tax effects, if any, associated
     therewith."


                                     3
<PAGE>


     5. Section 3(c) of the Agreement is hereby amended to add the following at
the end thereof, and a comparable change shall be made to the definition of Book
Value contained in Section 2(f) of the Certificate of Designations:

     "The 'Nashville Facility' shall mean the Nashville, Tennessee
     manufacturing facility of GAF Fiberglass."

     6. Section 4(b) of the Agreement is hereby amended to read in its entirety
as follows:

     "In each calendar year you may, at your option, exercisable by notice
     delivered to the Company on or before March 31 of that year, elect to
     sell and, upon the giving of the notice, the Company shall be
     obligated to purchase and you shall be obligated to sell as many
     Common Shares owned by you as you may elect to sell, at their Book
     Value determined as of the last day of the preceding calendar year,
     provided that you owned the Preferred Shares which were converted into
     such Common Shares on or before June 30 of the preceding calendar
     year."

     7. Section 4(d) of the Agreement is hereby amended to read in its entirety
as follows:

     "If you exercise the Option in whole or in part, convert Preferred
     Shares received upon exercise into Common Shares and exercise your
     right to sell such Common Shares to the Company as provided in Section
     4(a) or 4(b), the Company will reimburse you for all interest accrued,
     during the period commencing with the date of exercise of your right
     under Section 4(a) or 4(b) and ending with the date of purchase by the
     Company of your Common Shares, on any loan that financed the purchase
     of your Preferred Shares, provided that the terms of the loan and the
     lender are reasonably satisfactory to the Company. Such interest will
     be paid by the Company when the interest is payable to the lender. The
     Company will introduce you to lenders who the Company believes will be
     willing to provide financing for exercise of the Options."

     8. Section 4(e) of the Agreement is hereby amended to read in its entirety
as follows:

     "As used herein, the "Put/Call Period" shall mean the 30-day period
     commencing with the later of (i) the date which is six months after
     the date on which you exercised the Option to purchase the Preferred
     Shares which were converted into the applicable Common Shares or (ii)
     the Termination Date."


                                     4
<PAGE>


     9. Section 2(a) of the Certificate of Designation shall be amended to
replace "$2.00" with "$1.50" in the fourth and eight lines thereof.

     In all other respects, the Agreement shall remain in full force and
     effect.

     Capitalized terms used herein which are not defined shall have the meanings
ascribed to them in the Agreement.

     Please sign the enclosed copy of this letter to indicate your agreement to
the foregoing.


                                          Sincerely,

                                          BUILDING MATERIALS
                                            CORPORATION OF AMERICA

                                          By:  _________________________

AGREED:

----------------------------


                                       5
<PAGE>

                                                                          [Date]

TO EACH HOLDER OF OPTIONS
TO PURCHASE SHARES OF SERIES
A PREFERRED STOCK OF BUILDING
MATERIALS CORPORATION OF AMERICA

Dear Optionee:

     Reference is made to the Option Agreement dated July 1, 1997 (the
"Agreement") pursuant to which you were granted an option to purchase shares of
Series A Cumulative Redeemable Convertible Preferred Stock of Building Materials
Corporation of America.

     The Agreement is hereby amended as follows:

     1. The first sentence of Section 1(b) of the Agreement is hereby amended to
read in its entirety as follows:

     "The Option shall vest and become exercisable as to 20% of the
     Preferred Shares on June 30 in each of the years 1998 through 2002, in
     each case to the extent you are employed by the Company or its
     subsidiaries on such date; provided that (i) if your employment with
     the Company and its subsidiaries should terminate as a direct result
     of a divestiture (whether because you are employed by the business
     which is sold, your position is eliminated as a result of the
     divestiture or otherwise) or (ii) if, after a Change of Control of the
     Company, your employment with the Company and its subsidiaries (x)
     should be terminated by the Company other than for cause, (y) is
     terminated as a result of your death or permanent disability, or (z)
     is terminated by you for "good reason", the unvested portion of the
     Option shall become vested on the date of your termination. You shall
     be deemed to terminate your employment for "good reason" if you do so
     as a result of a change or changes in the terms of your employment
     that are materially adverse to you, including with respect to your
     salary and bonus, level of responsibility or geographic location of
     employment."


<PAGE>


     2. The first sentence of Section 1(c) of the Agreement is hereby amended to
read in its entirety as follows:

     "The Option will terminate on the earliest of (i) June 30, 2006, (ii)
     30 days after the termination of your employment with the Company and
     its subsidiaries for any reason other than your death or permanent
     disability or (iii) one year after the termination of your employment
     with the Company and its subsidiaries as a result of your death or
     permanent disability."

     3. Section 1(d) of the Agreement is hereby amended to read in its entirety
as follows:

     "Notwithstanding anything to the contrary contained in this Agreement,
     in the event the Company or its parent engages in a public offering of
     the common stock of the Company (an "IPO"), (i) you will be entitled
     to receive from the Company, on each vesting date set forth in Section
     1(b) (or, within five days after consummation of the IPO, in the case
     of the unexercised portion, if any, of the Option which is vested as
     of the date of consummation of the IPO), an amount in cash equal to
     the amount by which Book Value (as defined in Section 3(c)) of the
     Common Shares issuable upon conversion of the Preferred Shares subject
     to the portion of the Option which vests (or, in the case described in
     the immediately preceding parenthetical, is vested) on such date,
     determined as of the end of the calendar quarter immediately preceding
     the consummation of the IPO, exceeds the aggregate exercise price of
     such portion of the Option, and (ii) the Company will endeavor to
     grant you options to purchase shares of the Company's Common Stock
     which, together with the rights to receive cash described in clause
     (i) above, provide equivalent economic value to the Options granted to
     you pursuant to this Agreement that are unexercised as of the date of
     consummation of the IPO. Such new stock options will vest on the
     vesting schedule provided in Section 1(b) of this Agreement and will
     be granted under a stock option plan which is appropriate, in the
     judgment of the Board of Directors of the Company, for a public
     company. Your right to receive cash, and to exercise such new stock
     options, will be subject to the conditions to vesting set forth in
     Section 1(b), including the proviso to the first sentence thereof.
     Following consummation of the IPO, this Agreement (other than Section
     3(d) and this Section 1(d)) shall have no further force and effect."

     4. The first two sentences of Section 3(c) of the Agreement are hereby
amended to read in its entirety as follows, and a comparable change shall be
made to the first sentence of the definition of Book Value contained in Section
2(f) of the Certificate of Designation:

     "For purposes of this Agreement, 'Book Value' shall mean, as of any
     date of determination, (x) the sum of (i) the combined shareholder's
     equity


                                       2
<PAGE>


          of the Company and U.S. Intec, Inc. as of December 31, 1995
          determined in accordance with generally accepted accounting
          principles, (ii) the cumulative consolidated net income or loss
          of the Company (treating U.S. Intec Holdings Inc. as a
          wholly-owned subsidiary of the Company for all periods) for the
          period January 1, 1996 through the date of determination and
          (iii) the cumulative operating income (or loss), net of an amount
          equal to imputed income taxes on such operating income calculated
          at the same tax rate as is accrued as an expense by the Company
          in its income statement for the applicable period, of GAF
          Fiberglass Corporation ("GAF Fiberglass") for the period January
          1, 1997 through the date of determination, and adding back (A)
          the charge to shareholder's equity relating to the assumption by
          the Company of certain asbestos-related liabilities of GAF
          Building Materials Corporation in connection with the Company's
          formation and (B) the reduction in shareholder's equity resulting
          from purchases of the capital stock of GAF Corporation ("GAF") by
          persons who participated in promoting the management buy-out of
          GAF in March 1989 (the "Acquisition") (predecessor cost basis
          adjustment), and excluding, to the extent occurring after
          December 31, 1995, (1) nonrecurring non-operating losses and
          nonrecurring non-operating gains, including any further charge
          relating to asbestos-related liabilities, (2) net gains or losses
          in respect of dispositions of assets by the Company other than in
          the ordinary course of business, (3) any dividends or
          distributions paid to the holders of the Company's capital stock,
          (4) any capital contributions made to the Company by its
          stockholders, (5) any amounts received by the Company for shares
          of its capital stock (including from the exercise of options or
          warrants to purchase capital stock or from the conversion into
          capital stock of convertible debt or convertible preferred stock)
          and (6) any charges relating to amortization of goodwill and
          other intangibles arising from the Acquisition divided by (y)
          1,000,010. There shall be deducted from Book Value an amount
          equal to a 15% per annum charge on the aggregate capital
          contributions made to the Company by its stockholders during the
          period commencing October 1, 1997 and ending with the date of
          determination (the "Period"), amounts received by the Company
          during the Period for shares of its capital stock and, to the
          extent not actually charged to the Company, on the outstanding
          principal amount of loans and other advances made to the Company
          by affiliates (excluding subsidiaries of the Company) during the
          Period. There shall be added to Book Value a 15% per annum credit
          on the aggregate dividends or distributions made by the Company
          to its stockholders during the Period and, to the extent not
          actually charged to the borrower, on the outstanding principal
          amount of loans and other advances made by the Company to
          affiliates (excluding subsidiaries of the Company) during the
          Period. Any adjustments to Book Value (including the 15% charge
          and credit referred to in the preceding two sentences) shall
          include the tax effects, if any, associated therewith."


                                     3
<PAGE>


     5. Section 3(c) of the Agreement is hereby amended to add the following at
the end thereof, and a comparable change shall be made to the definition of Book
Value contained in Section 2(f) of the Certificate of Designations:

          "The 'Nashville Facility' shall mean the Nashville, Tennessee
          manufacturing facility of GAF Fiberglass."

     6. Section 4(b) of the Agreement is hereby amended to read in its entirety
as follows:

          "In each calendar year you may, at your option, exercisable by
          notice delivered to the Company on or before March 31 of that
          year, elect to sell and, upon the giving of the notice, the
          Company shall be obligated to purchase and you shall be obligated
          to sell as many Common Shares owned by you as you may elect to
          sell, at their Book Value determined as of the last day of the
          preceding calendar year, provided that you owned the Preferred
          Shares which were converted into such Common Shares on or before
          June 30 of the preceding calendar year."

     7. Section 4(d) of the Agreement is hereby amended to read in its entirety
as follows:

          "If you exercise the Option in whole or in part, convert
          Preferred Shares received upon exercise into Common Shares and
          exercise your right to sell such Common Shares to the Company as
          provided in Section 4(a) or 4(b), the Company will reimburse you
          for all interest accrued, during the period commencing with the
          date of exercise of your right under Section 4(a) or 4(b) and
          ending with the date of purchase by the Company of your Common
          Shares, on any loan that financed the purchase of your Preferred
          Shares, provided that the terms of the loan and the lender are
          reasonably satisfactory to the Company. Such interest will be
          paid by the Company when the interest is payable to the lender.
          The Company will introduce you to lenders who the Company
          believes will be willing to provide financing for exercise of the
          Options."

     8. Section 4(e) of the Agreement is hereby amended to read in its entirety
as follows:

          "As used herein, the "Put/Call Period" shall mean the 30-day
          period commencing with the later of (i) the date which is six
          months after the date on which you exercised the Option to
          purchase the Preferred Shares which were converted into the
          applicable Common Shares or (ii) the Termination Date."


                                       4
<PAGE>


     9. Section 2(a) of the Certificate of Designation shall be amended to
replace "$2.00" with "$1.50" in the fourth and eight lines thereof.

          In all other respects, the Agreement shall remain in full force
          and effect.

     Capitalized terms used herein which are not defined shall have the meanings
ascribed to them in the Agreement.

     Please sign the enclosed copy of this letter to indicate your agreement to
the foregoing.


                                               Sincerely,

                                               BUILDING MATERIALS
                                                 CORPORATION OF AMERICA

                                               By:  _________________________


AGREED:

----------------------------


                                       5