<PAGE>   1


                                                                     Exhibit 4.4



                          FIRST SUPPLEMENTAL INDENTURE

         This First Supplemental Indenture is dated as of April 15, 1998, among
American Architectural Products Corporation, a Delaware corporation (the
"Company"), each of Eagle & Taylor Company, Forte, Inc., Western Insulated
Glass, Co., Thermetic Glass, Inc., Binnings Building Products, Inc. (successor
by merger to BBPI Acquisition Corporation), Danvid Window Company (f/k/a DCI/DWC
Acquisition Corporation), American Glassmith Acquisition Corporation and Modern
Window Acquisition Corporation, as Subsidiary Guarantors, VinylSource, Inc., a
Delaware corporation ("VinylSource"), AAPC One Acquisition Corporation, a
Delaware corporation ("AAPC One"), AAPC Two Acquisition Corporation, a Delaware
corporation ("AAPC Two"), Denver Window Acquisition Corporation, a Delaware
corporation ("Denver Window"), Eagle Window & Door Center, Inc., a Delaware
corporation ("EWDC"), Weather-Seal Acquisition Corporation, a Delaware
corporation ("Weather-Seal") (VinylSource, AAPC One, AAPC Two, Denver Window,
EWDC and Weather-Seal are, collectively, the "New Subsidiary Guarantors") and
United States Trust Company of New York, a banking corporation organized and
existing under the laws of the State of New York, in its capacity as trustee
(the "Trustee"). Each defined term used herein shall have the meaning assigned
to it in the Indenture (hereinafter defined), unless the context hereof
otherwise requires or provides.

                                    RECITALS

         1. As of December 10, 1997, the Company, the Subsidiary Guarantors and
the Trustee executed an Indenture (the "Indenture") providing for the issuance
of $125,000,000 of the Company's 11 3/4% Senior Notes due 2007 (the "Notes").

         2. Section 4.20 of the Indenture permits, among other things,
Restricted Subsidiaries to guarantee Indebtedness if the Restricted Subsidiary
becomes a Subsidiary Guarantor by executing a supplemental indenture in which
such Restricted Subsidiary agrees to be bound by the terms of the Indenture as a
Subsidiary Guarantor and executes a Subsidiary Guarantee.

         3. VinylSource is a Restricted Subsidiary that proposes to guarantee
certain Indebtedness of the Company.

         4. AAPC One is a Restricted Subsidiary that proposes to guarantee
certain Indebtedness of the Company.

         5. AAPC Two is a Restricted Subsidiary that proposes to guarantee
certain Indebtedness of the Company.

         6. Denver Window is a Restricted Subsidiary that proposes to guarantee
certain Indebtedness of the Company.

         7. EWDC is a Restricted Subsidiary that proposes to guarantee certain
Indebtedness of the Company.

         8. Weather-Seal is a Restricted Subsidiary that proposes to guarantee
certain 

<PAGE>   2
                                                                Exhibit 4.4

Indebtedness of the Company.

         9. Section 9.01(a)(iv) of the Indenture permits the Indenture to be
amended or supplemented to add Subsidiary Guarantors with respect to the Notes
without the consent of any Noteholder.

         10. The Company, the Subsidiary Guarantors, the New Subsidiary
Guarantors and the Trustee agree as follows for the benefit of each other and
for the equal and ratable benefit of the Noteholders:

                                    ARTICLE 1

                         ADDITIONAL SUBSIDIARY GUARANTOR

         Section 1.01 GUARANTY. Each of the New Subsidiary Guarantors, by
executing this First Supplemental Indenture, agrees to be bound by the terms of
the Indenture as a Subsidiary Guarantor and agrees to execute a Subsidiary
Guarantee in the form attached hereto as Exhibit A.

         Section 1.02 FURTHER ASSURANCES. The parties will execute and deliver
such further instruments and do such further acts and things as may be
reasonably required to carry out the intent and purpose of this First
Supplemental Indenture.

         Section 1.03 TRUST INDENTURE ACT CONTROLS. If any provision of this
First Supplemental Indenture limits, qualifies or conflicts with another
provision hereof that is required to be included in this First Supplemental
Indenture by the TIA, the required provision shall control.

         Section 1.04 COUNTERPART ORIGINALS. This First Supplemental Indenture
may be executed in any number of counterparts, each of which so executed shall
be an original, but all of them together represent the same agreement.

         Section 1.04 HEADINGS. Headings of the Article and the Sections of this
First Supplemental Indenture have been inserted for convenience of reference
only, are not to be considered a part of this First Supplemental Indenture, and
shall in no way modify or restrict any of the terms of provisions hereof.

         Section 1.05 GOVERNING LAW. This First Supplemental Indenture shall be
governed by, and construed in accordance with, the laws of the State of New
York, but without giving effect to applicable principals of conflicts of law to
the extent that the application of the laws of another jurisdiction would be
required thereby.

         Section 1.06 SUCCESSORS. All agreements of the Company, the Subsidiary
Guarantors, the New Subsidiary Guarantors and the Trustee in this First
Supplemental Indenture shall bind their successors.

         Section 1.07 SEVERABILITY. In case any provision of this First
Supplemental Indenture shall be invalid, illegal, or unenforceable, the
validity, legality, and enforceability of the remaining 

<PAGE>   3
                                                                Exhibit 4.4

provisions shall not in any way be affected or impaired thereby.

         Section 1.08 INDENTURE REMAINS IN FULL FORCE AND EFFECT. Except to the
extent amended hereby or in connection herewith, all terms, provisions and
conditions of the Indenture, and all documents executed in connection therewith,
shall continue in full force and effect and shall remain enforceable and binding
in accordance with their terms. Except as specifically modified herein, the
Indenture remains unchanged and in full force and effect.

         Section 1.09 NO THIRD PARTY BENEFITS. Nothing in this First
Supplemental Indenture, express or implied, shall give to any Person, other than
the parties hereto and their successors under the Indenture, and the
Noteholders, any benefit or any legal or equitable right, remedy or claim under
the Indenture.

         Section 1.10 THE TRUSTEE. The Trustee shall not be responsible in any
manner for or in respect of the validity or sufficiency of this First
Supplemental Indenture, or for or in respect of the recitals contained herein,
all of which recitals are made by the Company solely.

         IN WITNESS WHEREOF, the parties hereto have caused this First
Supplemental Indenture to be duly executed as of the date first written above.

                                    American Architectural Products Corporation


                                    By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                             Frank J. Amedia
                                             President


                                    Eagle & Taylor Company


                                    By: /s/ Joseph Dominijanni
                                        ----------------------------------------
                                             Joseph Dominijanni
                                             Vice President


                                    Forte, Inc.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     Western Insulated Glass, Co.
<PAGE>   4
                                                                  Exhibit 4.4



                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              Chief Executive Officer


                                     Thermetic Glass, Inc.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     Binnings Building Products, Inc.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     Danvid Window Company


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     American Glassmith Acquisition Corporation


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     Modern Window Acquisition Corporation


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President

<PAGE>   5
                                                                Exhibit 4.4

                                     VinylSource, Inc.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     AAPC One Acquisition Corporation


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     AAPC Two Acquisition Corporation


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     Denver Window Acquisition Corporation


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     Eagle Window & Door Center, Inc.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President


                                     Weather-Seal Acquisition Corporation


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                              Frank J. Amedia
                                              President

<PAGE>   6

                                                        Exhibit 4.4


                                     United States Trust Company of New York


                                     By: /s/ Cynthia Chaney
                                        ----------------------------------------
                                              Cynthia Chaney
                                              Assistant Vice President






<PAGE>   7
                                                                Exhibit 4.4




FORM OF NOTATION ON SECURITY                                        Exhibit "A"
RELATING TO SUBSIDIARY GUARANTEE                                    -----------

                              SUBSIDIARY GUARANTEE
                              --------------------

         The Subsidiary Guarantors (as defined in the Indenture (the
"Indenture") referred to in the Note upon which this notation is endorsed and
hereinafter referred to as a "Subsidiary Guarantor," which term includes any
successor person under the primary obligor and not a surety, (such guarantee by
each Subsidiary Guarantor being referred to herein as the "Subsidiary
Guarantee") (a) the due and punctual payment of the principal, premium, if any,
and interest on the Notes, whether at Stated Maturity or interest payment date,
by acceleration, call for redemption or otherwise, (b) the due and punctual
payment of interest on the overdue principal of and interest, if any, on the
Notes, to the extent lawful, (c) the due and punctual performance of all other
monetary Obligations of the Company under the Indenture and the Notes to the
Noteholder or the Trustee, all in accordance with the terms set forth in Article
10 of the Indenture and (d) in case of any extension of time of payment or
renewal of any Notes or any such Obligations, the same will be promptly paid in
full when due or performed in accordance with the terms of the extension or
renewal, whether at Stated Maturity by acceleration or otherwise and (ii) have
agreed to pay any and all costs and expenses (including reasonable attorneys'
fees) incurred by the Trustee or any Noteholders in enforcing any rights under
this Subsidiary Guarantee.

         The Obligations of each Subsidiary Guarantor to the Holders of Notes
and to the Trustee pursuant to this Subsidiary Guarantee and the Indenture are
expressly set forth in Article 10 of the Indenture and reference is hereby made
to such Indenture for the precise terms of this Subsidiary Guarantee.

         No stockholder, officer, director or incorporator, as such, past,
present or future of any Subsidiary Guarantor shall have any liability under
this Subsidiary Guarantee by reason of his or its status as such stockholder,
officer, director or incorporator.

         This is a continuing Subsidiary Guarantee and, except as otherwise
expressly provided for in Section 10.06 of the Indenture, shall remain in full
force and effect and shall be binding upon the Subsidiary Guarantor and its
successors and assigns until full and final payment of all of the Company's
Obligations under the Notes and the Indenture and shall inure to the benefit of
the successors and assigns of the Trustee and the Noteholders and, in the event
of any transfer of the successors and assigns by any Noteholder or the Trustee,
the rights and privileges herein conferred upon that party shall automatically
extend to and be vested in such transferee or assignee, all subject to the terms
and conditions hereof. This is a Subsidiary Guarantee of payment and not of
collectability.

         This Subsidiary Guarantee shall not be valid or obligatory for any
purpose until the certificate of authentication on the Note upon which this
Subsidiary Guarantee is noted shall have been executed by the Trustee under the
Indenture by the manual signature of one of its authorized officers.

         THE TERMS OF ARTICLE 10 OF THE INDENTURE ARE INCORPORATED HEREIN 

<PAGE>   8
                                                                Exhibit 4.4

BY REFERENCE.


         Capitalized terms used herein have the same meanings given in the
Indenture unless otherwise indicated.

                                   Guarantors:

                                   VINYLSOURCE, INC.


                                    By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                      Name:  Frank J. Amedia
                                      Title:  President


                                    AAPC ONE ACQUISITION CORPORATION


                                    By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                      Name:  Frank J. Amedia
                                      Title:  President


                                    AAPC TWO ACQUISITION CORPORATION


                                    By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                      Name:  Frank J. Amedia
                                      Title:  President


                                    DENVER WINDOW ACQUISITION
                                    CORPORATION


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President


                                     EAGLE WINDOW & DOOR CENTER, INC.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
<PAGE>   9
                                                                Exhibit 4.4

                                       Title:  President


                                     WEATHER-SEAL ACQUISITION
                                     CORPORATION


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President


                                     EAGLE & TAYLOR COMPANY


                                     By: /s/ Joseph Dominijanni
                                        ----------------------------------------
                                       Name:  Joseph Dominijanni
                                       Title:  Vice President


                                     FORTE, INC.


                                     By: Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President


                                     WESTERN INSULATED GLASS, CO.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  Chief Executive Officer


                                     THERMETIC GLASS, INC.


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President

<PAGE>   10

                                                                Exhibit 4.4



                                     BBPI ACQUISITION CORPORATION


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President


                                     DANVID WINDOW COMPANY


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President


                                     AMERICAN GLASSMITH ACQUISITION
                                     CORPORATION


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President


                                     MODERN WINDOW ACQUISITION
                                     CORPORATION


                                     By: /s/ Frank J. Amedia
                                        ----------------------------------------
                                       Name:  Frank J. Amedia
                                       Title:  President