<PAGE>

                              ELEVENTH AMENDMENT
                                      to
               AMENDED AND RESTATED LOAN AND SECURITY AGREEMENT

     This Eleventh Amendment to Amended and Restated Loan and Security
Agreement (this "Amendment"), dated effective as of December 31, 1997 (the
"Effective Date"), is entered into among American Builders & Contractors
Supply Co., Inc., a Delaware corporation (such corporation, including its
predecessor in interest, the "Borrower") with its chief executive office
located at One ABC Parkway, Beloit, Wisconsin, the financial institutions
listed on the signature pages hereof (individually, a "Lender" and
collectively, the "Lenders") and NationsBank of Texas, N.A. ("NationsBank"),
as Agent for the Lenders (in such capacity, the "Agent"):


                             W I T N E S S E T H

     WHEREAS, the Borrower, the Lenders and ANB are party to that certain
Amended and Restated Loan and Security Agreement (the "Original Loan
Agreement") dated as of July 1, 1993, as amended by that certain First
Amendment to Amended and Restated Loan and Security Agreement dated as of
September 2, 1994 (the "First Amendment"), that certain Waiver and Second
Amendment to Amended and Restated Loan and Security Agreement dated June 19,
1995 (the "Second Amendment"), that certain Third Amendment to Amended and
Restated Loan and Security Agreement dated as of September 18, 1995 (the
"Third Amendment"), that certain Waiver and Fourth Amendment to Amended and
Restated Loan and Security Agreement dated as of September 30, 1995 (the
"Fourth Amendment"); that certain Waiver and Fifth Amendment to Amended and
Restated Loan and Security Agreement dated as of December 29, 1995 (the "Fifth
Amendment"), that certain Waiver and Sixth Amendment to Amended and Restated
Loan and Security Agreement dated as of February 8, 1996 (the "Sixth
Amendment"), that certain Waiver and Seventh Amendment to Amended and Restated
Loan and Security Agreement undated but entered into as of September 30, 1996
(the "Seventh Amendment"), that certain Waiver and Eighth Amendment to Amended
and Restated Loan and Security Agreement entered into as of March 27, 1997
(the "Eighth Amendment"), that certain Ninth Amendment to Amended and Restated
Loan and Security Agreement entered into as of May 7, 1997 (the "Ninth
Amendment") and the certain Tenth Amendment to Amended and Restated Loan and
Security Agreement entered into as of November 3, 1997 (the "Tenth Amendment")
(the Original Loan Agreement, as amended by the First Amendment, the Second
Amendment, the Third Amendment, the Fourth Amendment, the Fifth Amendment, the
Sixth Amendment, the Seventh Amendment, Eighth Amendment, the Ninth Amendment
and the Tenth Amendment, is referred to hereinafter as the "Loan Agreement")
pursuant to which Lenders have agreed to make certain loans and extend certain
other financial accommodations to the Borrower in an aggregate principal
amount of up to Two Hundred Million Dollars ($200,000,000.00) as provided
therein (terms defined by the Loan Agreement, where used in this Amendment,
shall have the same meanings in this Amendment as are prescribed by the Loan
Agreement);
<PAGE>

     WHEREAS, the Borrower has requested the Agent and the Lenders to modify
the Loan Agreement in certain respects and the Agent has agreed to do so
subject to the terms and conditions contained herein, and subject to
confirmation of consent by Requisite Lenders as required by Section 10.15 of
the Loan Agreement;

     NOW, THEREFORE, in consideration of the terms and conditions contained
herein, and of any loans or financial accommodations heretofore, now or
hereafter made to or for the benefit of the Borrower by the Lenders, it hereby
is agreed as follows:

     1.     Amendment to Section 8.18 of the Loan Agreement.  Section 8.18
("Maximum Funded Debt to EBITDA") of the Loan Agreement is hereby amended and
restated to read in its entirety as follows:

     8.18     Maximum Funded Debt to EBITDA.  The ratio of Funded Debt to
     EBITDA, determined as of the last day of each calendar quarter and
     measured for the preceding period of four calendar quarters, shall not
     exceed the following prescribed amounts, as applicable:

     Date                              Ratio
     ----                              -----
     December 31, 1997                 10.00 to 1.0
     March 31, 1998                    10.75 to 1.0
     June 30, 1998                      9.75 to 1.0
     September 30, 1998                 7.00 to 1.0
     December 31, 1998                  6.30 to 1.0
     March 31, 1999                     6.20 to 1.0
     June 30, 1999                      6.80 to 1.0
     September 30, 1999                 6.50 to 1.0
     December 31, 1999                  6.30 to 1.0
     March 31, 2000                     5.90 to 1.0
     June 30, 2000                      6.80 to 1.0

     2.     Representation and Warranties of Borrower.  The Borrower hereby
represents and warrants that as of the date of this Amendment (a) no event has
occurred and is continuing which, after giving effect to this Amendment,
constitutes a Default or an Event of Default, (b) the representations and
warranties of the Borrower contained in the Loan Agreement and the other
Financing Agreements are true and correct on and as of the date hereof to the
same extent as though made on and as of the date hereof, except to the extent
such representations and warranties specifically relate to an earlier date, in
which case they are true and correct as of such earlier date, (c) the
execution and delivery by the Borrower of this Amendment and the performance
by the Borrower of the Loan Agreement, as amended by this Amendment, are
within its corporate power and have been duly authorized by all necessary
corporate action, (d) this Amendment and the Loan Agreement, as amended by
this Amendment, are legal, valid and binding obligations of the Borrower
enforceable against the Borrower in accordance with their terms and (e) the
execution

                                      -2-
<PAGE>

and delivery by the Borrower of this Amendment and the performance by the
Borrower of the Loan Agreement, as amended by this Amendment, do not require
the consent of any Person and do not contravene the terms of the Borrower's
Articles of Incorporation or By-Laws or any indenture, agreement or
undertaking to which the Borrower is a party or by which the Borrower or any
of its property is bound.

     3.     Reference to and Effect on the Loan Agreement.  Except as
expressly provided herein, the Loan Agreement and all other Financing
Agreements shall remain unmodified and in full force and effect and are hereby
ratified and confirmed.  The execution, delivery and effectiveness of this
Amendment shall not operate as a waiver or forbearance of (a) any right, power
or remedy of the Lenders under the Loan Agreement or any of the other
Financing Agreements, or (b) any Default or Event of Default.  This Amendment
shall constitute a Financing Agreement.

     4.     Amendment Fee.  In consideration of this Amendment, Subject to
Section 2.10 of the Loan Agreement, on the signing of this Amendment the
Borrower shall pay to the Agent, for the benefit of the Lenders, an amendment
fee in the amount of Fifty Thousand Dollars ($50,000.00).

     5.     Fees, Costs and Expenses.  The Borrower agrees to pay on demand
all costs and expenses of the Agent in connection with the preparation,
negotiation, execution and delivery and closing of this Amendment and all
related documentation, including the fees and out-of-pocket expenses of
counsel for the Agent with respect thereto.

     6.     Counterparts.  This Amendment may be executed in any number of
counterparts and by different parties hereto as separate counterparts, each of
which counterparts, when so executed and delivered, shall be deemed to be an
original and all of which counterparts, when taken together, shall constitute
but one and the same agreement.  A telecopy of any such executed counterpart
shall be deemed valid and may be relied upon as an original.

     7.     Effectiveness.  This Amendment shall be deemed effective
prospectively as of the Effective Date specified in the preamble upon
execution by the Borrower, the Agent, the Co-Agent and sufficient of the
Lenders whose names appear on the signature pages below to constitute
Requisite Lenders (subject, however, to the prior satisfaction of all
conditions for effectiveness as specified by this Amendment).

     IN WITNESS WHEREOF, the parties hereto have executed this Amendment as of
the day and year first written above.





                             [SIGNATURES FOLLOW]

                                      -3-
<PAGE>

                               AMERICAN BUILDERS &
ATTEST:                        CONTRACTORS SUPPLY CO., INC.


By:                            By:
   -------------------------       ----------------------------------
Name:                          Name:     Kendra Story
     -----------------------        ---------------------------------
Title:                         Title:    Chief Financial Officer
      ----------------------         --------------------------------
                               Date:  March __, 1998

                                      -4-
<PAGE>

                               NATIONSBANK OF TEXAS, N.A.
                               In its capacity as Agent


                              By:
                                   ----------------------------------
                              Name:    Virginia Brown
                                    ---------------------------------
                              Title:    Senior Vice President
                                     --------------------------------
                              Date:  March __, 1998

                                      -5-
<PAGE>

                              AMERICAN NATIONAL BANK AND
                              TRUST COMPANY OF CHICAGO
                              In its capacity as Co-Agent


                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -6-
<PAGE>

                              NATIONSBANK OF TEXAS, N.A.
                              In its capacity as a Lender

                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -7-
<PAGE>

                              AMERICAN NATIONAL BANK AND
                              TRUST COMPANY OF CHICAGO
                              In its capacity as a Lender

                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -8-
<PAGE>

                              BANKAMERICA BUSINESS CREDIT, INC.

                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -9-
<PAGE>

                              LASALLE BUSINESS CREDIT, INC.

                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -10-
<PAGE>

                              HARRIS TRUST AND SAVINGS BANK

                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -11-
<PAGE>

                              FLEET CAPITAL CORPORATION

                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -12-
<PAGE>

                              SANWA BUSINESS CREDIT CORPORATION

                              By:
                                   ----------------------------------
                              Name:
                                    ---------------------------------
                              Title:
                                     --------------------------------
                              Date:  March __, 1998

                                      -13-
<PAGE>

                 CONSENT AND AGREEMENT BY VALIDITY GUARANTORS

     Each of the undersigned consents to the foregoing Eleventh Amendment to
Amended and Restated Loan and Security Agreement ("Amendment") and each of the
undersigned agrees to the continued effectiveness of the Validity
Certification, respectively, previously executed and delivered by the
undersigned for the benefit of the Agent and the Lenders.  All references in
the each Validity Certification, respectively, to the Amended and Restated
Loan and Security Agreement shall be deemed to be to the Amended and Restated
Loan and Security Agreement as amended by the Amendment and all prior and
subsequent amendments thereto.  This agreement has been executed as of the
Effective Date specified in the Amendment.


                                   -------------------------------------
                                           Kenneth A. Hendricks


                                   ------------------------------------
                                             Kendra A. Story

                                      -14-