<PAGE>
 
                                                                 EXHIBIT 10.27
     
                          AGREEMENT AND PLAN OF MERGER

                                  BY AND AMONG

                        GROUP MAINTENANCE AMERICA CORP.

                             YALE ACQUISITION CORP.

                               YALE INCORPORATED

                                      AND

                               THE HOLDERS OF THE
                           OUTSTANDING CAPITAL STOCK
                                       OF
                               YALE INCORPORATED

                                August 18, 1997
<PAGE>
 
                               TABLE OF CONTENTS

<TABLE> 
<CAPTION> 
                                                                                              Page 
<S>                                                                                           <C>  
1.  THE MERGER..............................................................................   1
        1.1     The Merger..................................................................   1
        1.2     Effective Time of the Merger................................................   1
        1.3     Closing.....................................................................   1
        1.4     Effects of the Merger.......................................................   2
                1.4.1  At the Effective Time................................................   2
                1.4.2  Effects on the Surviving Corporation.................................   2
        1.5     Written Consents and Other Actions..........................................   3
                1.5.1  Unanimous Written Consent of the Shareholders; Other Matters.........   3
                1.5.2  Written Consent of the Sole Shareholder of Merger Sub................   3
                1.5.3  All Other Necessary Actions..........................................   3
        1.6     Conversion of Stock.........................................................   3
                1.6.1  Merger Sub Capital Stock.............................................   3
                1.6.2  Cancellation of the Company Treasury Stock...........................   3
                1.6.3  Merger Consideration.................................................   3
        1.7     Exchange of and Payment for Stock...........................................   4
                1.7.1  Delivery of Company Common Stock and Closing Merger Consideration....   4
                1.7.2  Assignments..........................................................   4
                1.7.3  Payment In Full Satisfaction of All Rights...........................   4
        1.8     Determination of Closing Merger Consideration...............................   4
                1.8.1  Delivery of IPO Price to Public; Statement...........................   4
        1.9     Post-Closing Determination of Total Consideration...........................   4
                1.9.1  Statement............................................................   4
                1.9.2  Review...............................................................   5
                1.9.3  Disputes.............................................................   5
                1.9.4  Resolution by Parties................................................   5
                1.9.5  Final Determination..................................................   5
                1.9.6  Expenses.............................................................   6

2.  REPRESENTATIONS AND WARRANTIES OF THE COMPANY AND THE SHAREHOLDER.......................   6
        2.1     Exhibit 2...................................................................   6
        2.2     Stock Ownership.............................................................   6
        2.3     Authority...................................................................   6
        2.4     Consents....................................................................   6
</TABLE>

                                       i
<PAGE>
 
<TABLE> 
<CAPTION> 
<S>                                                                                           <C> 
3.  REPRESENTATIONS AND WARRANTIES OF THE PARENT AND MERGER SUB..............................  7
        3.1     Representations and Warranties..............................................   7
                3.1.1    Organization.......................................................   7
                3.1.2    Capitalization of the Parent.......................................   7
                3.1.3    Authority..........................................................   7
                3.1.4    Consents...........................................................   7
                3.1.5    Defaults...........................................................   7
                3.1.6    Investment Company.................................................   8
                3.1.7    Financial Statements...............................................   8
                3.1.8    Taxes..............................................................   8
                3.1.9    Full Authority.....................................................   8
                3.1.10   Access.............................................................   8
                3.1.11   Disclosure.........................................................   8
                3.1.12   Parent Material Adverse Effect.....................................   9
                3.1.13   Tax-Free Reorganization............................................   9
                3.1.14   Value of Parent Common Stock.......................................  10
        3.2     Representations and Warranties Concerning the Merger Sub....................  10
                3.2.1    Organization and Standing..........................................  10
                3.2.2    Capital Structure..................................................  10
                3.2.3    Authority..........................................................  10

4.  CERTAIN COVENANTS, AGREEMENTS AND PRE-CLOSING MATTERS...................................  10
        4.1     Agreements of the Shareholders to be Effective Upon Closing.................  10
                4.1.1  Covenant Not to Compete..............................................  10
                4.1.2  Release..............................................................  11
        4.2     Elimination of Expense......................................................  11
        4.3     Deferred Compensation Plans.................................................  11
        4.4     Audit.......................................................................  12
        4.5     Certain Payables and Receivables............................................  12
        4.6     Pre-Closing Covenants and Agreements........................................  12
        4.7     Confidentiality.............................................................  12
        4.8     Tax-Free Reorganization.....................................................  12
        4.9     Company Plans...............................................................  12
        4.10    Purchase of Certain Receivables.............................................  12
        4.11    Income Tax Distribution.....................................................  13

5.  CONDITIONS PRECEDENT; CLOSING DELIVERIES................................................  13
        5.1  Conditions Precedent to the Obligations of the Parent and Merger Sub...........  13
             5.1.1  Accuracy of Representations and Warranties..............................  13
             5.1.2  Performance of Covenants................................................  13
             5.1.3  Legal Actions or Proceedings............................................  13
             5.1.4  Approvals...............................................................  13
</TABLE> 

                                     -ii-
<PAGE>
 
<TABLE> 
<S>                                                                                           <C> 
                5.1.5   Closing Deliveries..................................................     14
                5.1.6   No Casualty, Loss or Damage.........................................     14
                5.1.7   Licenses, etc.......................................................     14
                5.1.8   No Material Adverse Change..........................................     14
                5.1.9   IPO.................................................................     14 
                5.1.10  Certain Corporate Actions...........................................     14
        5.2     Conditions Precedent to the Obligations of the Shareholders and the Company.     14
                5.2.1   Accuracy of Representations and Warranties..........................     14
                5.2.2   Performance of Covenants............................................     14
                5.2.3   Approvals...........................................................     14
                5.2.4   Closing Deliveries..................................................     15
        5.3     Deliveries by the Shareholders at the Closing...............................     15
                5.3.1   Closing Certificates................................................     15
                5.3.2   Stock Transfer Restriction Agreement................................     15
                5.3.3   Employment Agreements...............................................     15
                5.3.4   Lease Agreement.....................................................     15
                5.3.5   Registration Rights Agreement.......................................     15
                5.3.6   Opinion of Counsel for the Shareholders and the Company.............     15
                5.3.7   Documents, Stock Certificates.......................................     15
                5.3.8   Discharge of Indebtedness, Releases, Etc............................     15
        5.4     Deliveries by the Parent at the Closing.....................................     16
                5.4.1   Closing Certificates................................................     16
                5.4.2   Registration Rights Agreement.......................................     16
                5.4.3   Opinion of Counsel for the Parent and Merger Sub....................     16
                5.4.4   Closing Merger Consideration........................................     16
                                                                                                   
6. SURVIVAL, INDEMNIFICATIONS...............................................................     17
        6.1     Survival....................................................................     17
        6.2     Indemnification.............................................................     17
                6.2.1   Parent Indemnified Parties..........................................     17
                6.2.2   Parent Indemnity....................................................     18
        6.3     Limitations.................................................................     18
        6.4     Procedures for Indemnification..............................................     18
                6.4.1   Notice..............................................................     18
                6.4.2   Legal Defense.......................................................     19
                6.4.3   Settlement..........................................................     19
                6.4.4   Cooperation.........................................................     19
        6.5     Subrogation.................................................................     20
                                                                                                   
7.  TERMINATION.............................................................................     20
        7.1  Grounds for Termination........................................................     20
                7.1.1   Mutual Consent......................................................     20
                7.1.2   Optional By the Company.............................................     20 
 </TABLE>

                                     -iii-
<PAGE>
 
<TABLE> 
<S>                                                                                            <C> 
                7.1.3   Optional By the Parent..............................................   20
                7.1.4   Breach By the Parent or Merger Sub..................................   20
                7.1.5   Breach by the Company or any Shareholder............................   20
           7.2  Effect of Termination.......................................................   20

8. MISCELLANEOUS............................................................................   20
         8.1    Notice......................................................................   20
         8.2    Further Documents...........................................................   21
         8.3    Assignability...............................................................   21
         8.4    Exhibits and Schedules......................................................   21
         8.5    Sections and Articles.......................................................   21
         8.6    Entire Agreement............................................................   21
         8.7    Headings....................................................................   22
         8.8    CONTROLLING LAW.............................................................   22
         8.9    Public Announcements........................................................   22
         8.10   No Third Party Beneficiaries................................................   22
         8.11   Amendments and Waivers......................................................   22
         8.12   No Employee Rights..........................................................   22
         8.13   Non-Recourse................................................................   23
         8.14   When Effective..............................................................   23
         8.15   Takeover Statutes...........................................................   23
         8.16   Number and Gender of Words..................................................   23
         8.17   Invalid Provisions..........................................................   23
         8.18   Multiple Counterparts.......................................................   23
         8.19   No Rule of Construction.....................................................   23
         8.20   Expenses....................................................................   24
</TABLE>

                                     -iv-
<PAGE>
 
                               LIST OF EXHIBITS
<TABLE>
<S>                                  <C>
Exhibit 1.....................................................Determination of Final Merger Consideration
Exhibit 1.5.1...................................................Unanimous Written Consent of.Shareholders
Exhibit 1.5.2...............................Written Consent of Sole Shareholder of Yale Acquisition Corp.
Exhibit 1.7.........................................................................Letter of Transmittal
Exhibit 2..............................................................................Certain Statements
Exhibit 2.2.............................................................Ownership of Company Common Stock
Exhibit 3.1.4..................................................................Required Consents - Parent
Exhibit 4.3......................... Procedure for Satisfaction of Deferred Compensation Plan Liabilities
Exhibit 4.6.............................................................................Certain Covenants
Exhibit 4.9.............................................................Company Plans to Remain in Effect
Exhibit 4.11.................................................................................Form of Note
Exhibit 5.3.2........................................................Stock Transfer Restriction Agreement
Exhibit 5.3.3..............................List of Employees to Execute and Deliver Employment Agreements
Exhibit 5.3.3A.......................................................................Employment Agreement
Exhibit 5.3.4.............................................................................Lease Agreement
Exhibit 5.3.5...............................................................Registration Rights Agreement
Exhibit 5.3.6......................................Opinion of.Counsel to the Shareholders and the Company
Exhibit 5.3.8......................................................................Terminated Obligations
Exhibit 5.4.3............................................................Opinion of Counsel to the Parent
</TABLE>

                                      -v-
<PAGE>
 
                             INDEX OF DEFINED TERMS
<TABLE>
<S>                                                              <C>
Accountants................................................................... 4
Additional Consideration...................................................... 6
Agreement..................................................................... 1
Applicable Corporate Law...................................................... 1
Business Time..................................................  Exhibit 5.3.3.A
Closing....................................................................... 1
Closing Date.................................................................. 1
Closing Merger Consideration.......................................... Exhibit 1
Closing Outstanding Common Stock Number............................... Exhibit 1
Closing Per Share Cash Amount......................................... Exhibit 1
Closing Per Share Common Stock Amount................................. Exhibit 1
Code.......................................................................... 1
Company....................................................................... 1
Company Accountants.......................................................... 13
Company Common Stock.......................................................... 1
Company Option Plan.......................................................... 14
Company Options.............................................................. 14
Converted Share............................................................... 4
Earn-Out Period............................................................... 6
EBITDA........................................................................ 6
Effective Time................................................................ 1
Excess Expense Level Deduction........................................ Exhibit 1
Final Outstanding Common Stock Number................................. Exhibit 1
Final Per Share Cash Amount........................................... Exhibit 1
Final Per Share Common Stock Amount................................... Exhibit 1
GAAP.................................................................. Exhibit 1
HSR Act...................................................................... 14
Indemnified Party............................................................ 21
Indemnifying Party........................................................... 21
Investments........................................................... Exhibit 1
IPO........................................................................... 2
IPO Price to the Public............................................... Exhibit 1
Long-Term Debt........................................................ Exhibit 1
Losses....................................................................... 20
Measurement Month Date................................................ Exhibit 1
Merger........................................................................ 1
Merger Sub.................................................................... 1
Minimum Proceeds.............................................................. 2
MMR.......................................................................... 12
Monthly Balance Sheet............................................... Exhibit.4.6
Notice of Dispute............................................................. 5
</TABLE>

                                     -vi-
<PAGE>
 
<TABLE> 
<S>                                                                   <C> 
Other Ownership Interests............................................   Exhibit 1
Owner's Policies of Title Insurance.................................. Exhibit 4.6
Parent......................................................................... 1
Parent Common Stock............................................................ 1
Parent Financial Statements...................................................  9
Parent Financial Statements...................................................  8
Parent Indemnified Parties.................................................... 17
Parent Indemnified Parties.................................................... 20
Parent Material Adverse Effect................................................ 10
Parent Material Adverse Effect................................................. 9
Parent Preferred Stock......................................................... 7
Parent Preferred Stock......................................................... 8
Parent Related Documents....................................................... 7
Parent Related Documents....................................................... 8
Permitted Exceptions................................................. Exhibit 4.6
Price Notice................................................................... 4
Principal Shareholders......................................................... 1
Registration Statement......................................................... 7
Registration Statement......................................................... 8
SEC............................................................................ 8
SEC............................................................................ 7
Securities Act................................................................. 2
Settlement Notice..............................................................22
Settlement Notice..............................................................19
Shareholder.................................................................... 1
Shareholder Related Document................................................... 6
Shareholder Related Document................................................... 7
Shareholders................................................................... 1
Statement of Closing Consideration............................................. 4
Statement of Final Per Share Amounts........................................... 5
Statement of Closing Consideration............................................. 4
Statement of Final Per Share Amounts........................................... 5
Stock Certificate.............................................................. 4
Stock Certificate.............................................................. 3
Stock Value.................................................................... 6
Surveys.............................................................. Exhibit 4.6
Survival Period................................................................19
Survival Period................................................................17
Surviving Corporation.......................................................... 1
Terminated Obligations.........................................................18
Terminated Obligations.........................................................16
Third Accountants.............................................................. 5
Title Commitments.................................................... Exhibit 4.6
</TABLE> 

                                     -vii-
<PAGE>
 
<TABLE>
<S>                                                              <C>
Title Insurance Property.........................................Exhibit 4.6
Total Consideration............................................... Exhibit 1
Transaction Costs................................................. Exhibit 1
Working Capital................................................... Exhibit 1
Working Capital Addition.......................................... Exhibit 1
Working Capital Deduction......................................... Exhibit 1
</TABLE>

                                    -viii-
<PAGE>
 
                          AGREEMENT AND PLAN OF MERGER
                          ----------------------------


     This AGREEMENT AND PLAN OF MERGER (this "Agreement") made effective as of
                                              ---------                       
August ___, 1997, by and among Group Maintenance America Corp., a Texas
corporation (the "Parent"), Yale Acquisition Corp., a Minnesota corporation
                  ------                                                   
("Merger Sub"), Yale Incorporated, a Minnesota corporation (the "Company"), and
  ----------
the undersigned holders of all of the outstanding capital stock of the Company
(the "Shareholders").
      ------------   

     WHEREAS, the respective Boards of Directors of the Parent, Merger Sub and
the Company have each approved the merger of the Company with and into Merger
Sub (the "Merger") pursuant to this Agreement and the applicable statutes of the
          ------                                                                
State of  Minnesota and pursuant to the Merger each issued and outstanding share
of Common Stock, no par value, of the Company ("Company Common Stock") will be
                                                --------------------          
converted into the right to receive certain shares of common stock, $.001 par
value per share, of the Parent ("Parent Common Stock"), and certain cash
                                 -------------------                    
consideration, all as provided herein;

     WHEREAS, the Merger has been approved, as required by applicable law, by
the Parent, acting as sole shareholder of Merger Sub, and by the Shareholders.

     WHEREAS, for federal income tax purposes, it is intended that the Merger
shall qualify as a reorganization within the meaning of Section 368(a) of the
Internal Revenue Code of 1986, as amended (the "Code").
                                                ----   

     NOW, THEREFORE, in consideration of the premises and the representations,
warranties and agreements herein contained, the parties hereto agree as follows:

                                1.  THE MERGER

      1.1 The Merger.  Subject to the terms and conditions hereof, and in
          ----------                                                     
accordance with the Minnesota Business Corporation Act (the "Applicable
                                                             ----------
Corporate Law") upon the Effective Time (as defined in Section 1.2), the Company
-------------                                                                   
shall be merged with and into Merger Sub.  Merger Sub, as the surviving entity
following the Merger, is sometimes referred to in this Agreement as the
"Surviving Corporation."
 ---------------------  

      1.2 Effective Time of the Merger.  In accordance with the requirements of
          ----------------------------                                         
applicable law, appropriate Articles of Merger under the Applicable Corporate
Law shall be prepared, executed and submitted for filing with the Secretary of
State of the State of Minnesota immediately following and on the same day as the
Closing (as defined below).  The date of such filing is referred to in this
Agreement as the "Effective Time."
                  --------------  

      1.3 Closing.  The closing of the Merger ("Closing") will take place at the
          -------                               -------                         
offices of Bracewell & Patterson, L.L.P. in Houston, Texas on a date that is
contemporaneous with the closing of the Parent's IPO (as defined below), but in
no event later than December 31, 1997 ("Closing Date"); provided that each of
                                        ------------                         
the conditions precedent to the obligations of the parties to effect the Merger
set forth in Article 5 of this Agreement are then satisfied or waived by the
applicable party.  The parties may agree in writing on another place for the
Closing.  At the Closing, the parties will deliver or cause to be delivered the
documents described in Sections 5.3 and 5.4 below.  The term "IPO" means the
                                                              ---           
first underwritten public offering of 
<PAGE>
 
Parent Common Stock resulting in net cash proceeds to the Parent of at least the
Minimum Proceeds, as defined below (other than any offering pursuant to any
registration statement relating to any capital stock of the Parent or options,
warrants or other rights to acquire any such capital stock issued or to be
issued primarily to directors, officers or employees of the Parent or any of its
subsidiaries, (i) relating to any employee benefit plan or interest therein,
(ii) relating principally to any preferred stock or debt securities of the
Parent, or (iii) filed pursuant to Rule 145 under the Securities Act of 1933, as
amended ("Securities Act"), or any successor or similar provision). The term
          --------------
"Minimum Proceeds" means the aggregate amount necessary to pay in full (i) all
 ----------------
indebtedness of the Parent or any of its subsidiaries outstanding at the closing
of the IPO and incurred for purposes of financing any acquisitions by the Parent
or any of its subsidiaries (including the refinancing of acquired company
indebtedness), (ii) the aggregate redemption prices for the redemption of all of
the Parent's preferred stock outstanding at the closing of the IPO issued by the
Parent in connection with then completed acquisitions by the Parent or any of
its subsidiaries, and (iii) the aggregate cash payable by the Parent or any of
its subsidiaries in connection with all then pending acquisitions.

      1.4 Effects of the Merger.
          --------------------- 

          1.4.1  At the Effective Time.  At the Effective Time, (i) the Company
                 ---------------------                                         
shall merge with and into Merger Sub and as a result thereof, the separate
existence of the Company shall cease, (ii) the Articles of Incorporation of
Merger Sub, as in effect immediately prior to the Effective Time, shall be the
Articles of Incorporation of the Surviving Corporation, except that the Articles
of Incorporation of Merger Sub shall be amended to provide that the name of the
Surviving Corporation shall be changed to "Yale Incorporated," (iii) the Bylaws
of Merger Sub as in effect immediately prior to the Effective Time shall be the
Bylaws of the Surviving Corporation, and (iv) the directors and officers of
Merger Sub immediately prior to the Effective Time shall become the directors
and officers of the Surviving Corporation, until the earlier of their
resignation or removal or until their respective successors are duly elected or
appointed, as the case may be.

          1.4.2  Effects on the Surviving Corporation.  As of and after the
                 ------------------------------------                      
Effective Time, the Surviving Corporation shall possess all the rights,
privileges, immunities and franchises of a public as well as of a private nature
previously belonging to the Company and Merger Sub; and all property (real,
personal and mixed), and all debts due on whatever account, including
subscriptions to shares, and all other choses in action, and all and every other
interest of or belonging to or due to each of the Company and Merger Sub shall
be transferred to, and vested in, the Surviving Corporation without further act
or deed; and all such property, rights and privileges, powers and franchises and
all and every other interest shall be thereafter the property of the Surviving
Corporation as they were of the Company and Merger Sub; and the title to any
real estate, or interest therein, whether by deed or otherwise, shall not revert
or be in any way impaired by reason of the Merger.  The Surviving Corporation
shall be responsible and liable for all the liabilities and obligations of the
Company and Merger Sub, and any claim existing, or action or proceeding pending,
by or against the Company or Merger Sub may be prosecuted against the Surviving
Corporation.  Neither the rights of creditors nor any liens upon the property of
the Company or Merger Sub shall be impaired by the Merger, and all debts,
liabilities and duties of each of the Company and Merger Sub shall attach to the
Surviving Corporation, and may be enforced against it to the same extent as if
such debts, liabilities and duties had been incurred or contracted by it, all in
accordance with the Applicable Corporate Law and the terms of this Agreement.

                                      -2-
<PAGE>
 
      1.5 Written Consents and Other Actions.
          ---------------------------------- 

          1.5.1  Unanimous Written Consent of the Shareholders; Other Matters.
                 ------------------------------------------------------------ 
Contemporaneously with the execution hereof, the Shareholders (i) are executing
and delivering to the Company a Unanimous Written Consent in substantially the
form of Exhibits Exhibit 1.5.1 attached hereto and (ii) hereby acknowledge that
they are aware of their dissenter's or appraisal rights and with respect to the
Merger and their receipt of a copy of the provisions of Section 49.41 of the
Applicable Corporate Law and have elected not to exercise such rights.

          1.5.2  Written Consent of the Sole Shareholder of Merger Sub.
                 -----------------------------------------------------  
Contemporaneously with the execution hereof, the Parent is executing and
delivering to Merger Sub a written consent of the sole shareholder of Merger
Sub, in the form of Exhibits Exhibit 1.5.2 attached hereto, pursuant to the
applicable provisions of the Applicable Corporate Law, adopting this Agreement.

          1.5.3  All Other Necessary Actions.  In addition to the actions set
                 ---------------------------                                 
forth in Sections 1.5.1 and 1.5.2, the Parent, Merger Sub and the Company will
take all actions necessary in accordance with the Applicable Corporate Law and
their respective articles of incorporation and bylaws to cause the Merger to be
consummated on, and subject to, the terms set forth in this Agreement and the
Applicable Corporate Law.

      1.6 Conversion of Stock.  As of the Effective Time, by virtue of the
          -------------------                                             
Merger and without further action on the part of any holder of shares of Company
Common Stock or any holder of shares of capital stock of Merger Sub:

          1.6.1  Merger Sub Capital Stock. Each share of capital stock of Merger
                 ------------------------      
Sub issued and outstanding at the Effective Time shall remain outstanding and
shall be unchanged at and after the Merger and immediately following the
Effective Time shall constitute all of the issued and outstanding capital stock
of the Surviving Corporation.

          1.6.2  Cancellation of the Company Treasury Stock.  All shares of
                 ------------------------------------------                
Company Common Stock that are owned by the Company as treasury stock or by any
of its subsidiaries shall be canceled and retired and shall cease to exist and
no stock of the Parent or other consideration shall be delivered in exchange
therefor.

          1.6.3  Merger Consideration. Each share of Company Common Stock (other
                 --------------------     
than shares to be canceled in accordance with Section 1.6.2) shall be converted
into the right to receive (i) that number of shares of Parent Common Stock equal
to the Final Per Share Common Stock Amount (as defined in Exhibits Exhibit 1
attached hereto), and (ii) cash equal to the Final Per Share Cash Amount (as
defined in Exhibit 1 attached hereto). Each share of Company Common Stock so
converted into the right to receive cash equal to the Final Per Share Cash
Amount and shares of Parent Common Stock equal to the Final Per Share Common
Stock Amount (a " Converted Share") shall, by virtue of the Merger and without
                  ---------------                                             
any action on the part of the holder thereof, at the Effective Time no longer be
outstanding and shall at such time be canceled and retired and shall cease at
such time to exist, and each holder of a certificate which prior to the
Effective Time validly evidenced any such Converted Share (a "Stock
                                                              -----
Certificate") shall thereafter cease to have any rights with respect to such
-----------
Converted Share, except, upon the surrender of the Stock Certificate and a duly
executed and completed letter of transmittal in accordance with Section 1.7, the
right to receive such cash and Parent Common Stock at the times and in the
manner set forth herein.

                                      -3-
<PAGE>
 
      1.7 Exchange of and Payment for Stock.
          --------------------------------- 

          1.7.1  Delivery of Company Common Stock and Closing Merger
                 ---------------------------------------------------
Consideration.  Prior to the Closing, the Parent will deliver to each
-------------
Shareholder a letter of transmittal, in substantially the form attached hereto
as Exhibits Exhibit 1.7, to be used for the purpose of surrendering to the
Parent Stock Certificates in exchange for the right to receive the Final Per
Share Cash Amount and the Final Per Share Common Stock Amount for each Converted
Share evidenced by such Stock Certificate.  All of the Company Common Stock held
by the Shareholders will be surrendered by the Shareholders to the Parent
together with properly completed and executed letters of transmittal (with each
such signature guaranteed by a commercial bank or notarized by a notary public
or similar official reasonably satisfactory to the Parent), and the Parent shall
cause to be delivered to the Shareholders at the Closing the Closing Per Share
Cash Amount (as defined in Exhibit 1 attached hereto) and the Closing Per Share
Common Stock Amount (as defined in Exhibit 1 attached hereto) applicable to each
of the Converted Shares evidenced by the Stock Certificates properly surrendered
(with properly executed and completed letters of transmittal) by each
Shareholder to the Parent.

          1.7.2  Assignments. Except for the granting of options to employees of
                 -----------          
the Company and the exercise or assignment thereof as permitted by Section 4.10,
the assignment, transfer or other disposition of record or beneficial ownership
of any shares of Company Common Stock may not be made on or after the date
hereof.

          1.7.3  Payment In Full Satisfaction of All Rights. The delivery of the
                 ------------------------------------------ 
Closing Per Share Cash Amount and the Closing Per Share Common Stock Amount to
the Shareholders with respect to their Converted Shares shall be deemed to be
payment in full satisfaction of all rights pertaining to the outstanding
Converted Shares except for the right to receive additional shares of Parent
Common Stock and cash pursuant to Section 1.9.

      1.8 Determination of Closing Merger Consideration.
          --------------------------------------------- 

          1.8.1  Delivery of IPO Price to Public; Statement. Within five
                 ------------------------------------------   
business days after the Parent and its underwriters agree on the initial price
to the public for a share of Parent Common Stock offered in the IPO, as set
forth in an executed underwriting agreement, the Parent shall deliver to the
Shareholders a written notice (the "Price Notice") setting forth such initial 
                                    ------------     
price to the public and a statement setting forth a calculation of the Closing
Outstanding Common Stock Number (as defined in Exhibit 1 attached hereto), the
Closing Per Share Cash Amount, the Closing Per Share Common Stock Amount and the
Closing Merger Consideration (as defined in Exhibit 1 attached hereto), payable
to the Shareholders at Closing (the "Statement of Closing Consideration"). The
                                     ---------------------------------- 
initial price to the public of a share of Parent Common Stock, as set forth in
the Price Notice, and the Closing Outstanding Common Stock Number, the Closing
Per Share Cash Amount, the Closing Per Share Common Stock Amount and the Closing
Merger Consideration, as set forth in the Statement of Closing Consideration,
shall be final, conclusive and binding for purposes of this Agreement.

      1.9 Post-Closing Determination of Total Consideration.
          ------------------------------------------------- 

          1.9.1  Statement.  No later than 90 days after the Closing, the Parent
                 ---------                                                      
shall deliver to the Shareholders a statement showing the Final Outstanding
Common Stock Number (as defined in Exhibit 1 attached hereto), the Final Per
Share Cash Amount, the Final Per Share Common Stock Amount and the 

                                      -4-
<PAGE>
 
Total Consideration (as defined in Exhibit 1 attached hereto) (the "Statement of
                                                                    ------------
Final Per Share Amounts"). For purposes of determining the Statement of Final
-----------------------
Per Share Amounts, the Final Outstanding Common Stock Number, the Final Per
Share Cash Amount, the Final Per Share Common Stock Amount and the Total
Consideration shall be calculated or determined as of the last day of the month
immediately preceding the month in which the Closing occurs (unless the Closing
occurs on the last day of the month, in which case the Closing Date will be
used).

          1.9.2  Review.  After delivery to the Shareholders of the Statement of
                 ------                                                         
Final Per Share Amounts, the Shareholders and their representatives shall be
afforded the opportunity to review and inspect all of the financial records,
work papers, schedules and other supporting papers relating to the preparation
of the Statement of Final Per Share Amounts, and to consult with the Parent and
its representatives regarding the methods used in the preparation of the
Statement of Final Per Share Amounts.

          1.9.3  Disputes.  The Final Outstanding Common Stock Number, the Final
                 --------                                                       
Per Share Cash Amount, the Final Per Share Common Stock Amount and the Total
Consideration as shown on the Statement of Final Per Share Amounts shall be
final, conclusive and binding for purposes of this Agreement, unless the
Shareholders shall deliver to the Parent a written notice of disagreement
("Notice of Dispute") with any item or items in the Statement of Final Per Share
  -----------------                                                             
Amounts within 10 business days following receipt of the Statement of Final Per
Share Amounts, specifying in reasonable detail the nature and extent of such
disagreement; provided, however, that no Notice of Dispute may be given with
respect to any items unless such item involves an amount of $1,000 or more and
provided further that in the event such disagreement involves an amount less
than $1,000, the Statement of Final Per Share Amounts shall be final, conclusive
and binding.  If a Notice of Dispute is not properly given within such time, the
Final Outstanding Common Stock Number, the Final Per Share Cash Amount, the
Final Per Share Common Stock Amount and the Total Consideration as set forth in
the Statement of Final Per Share Amounts shall be final, conclusive and binding
for purposes of this Agreement.

          1.9.4  Resolution by Parties.  If  a Notice of Dispute is properly
                 ---------------------                                      
given, the Parent and the Shareholders agree to negotiate in good faith and use
their best efforts to resolve any disagreement with respect to the Statement of
Final Per Share Amounts.  If the Parent and the Shareholders shall not reach
such resolution within 30 days following receipt by the Parent of a properly
given Notice of Dispute, KPMG Peat Marwick LLP (the "Accountants") shall resolve
                                                     -----------                
such dispute within 30 days after its submission to them. The Parent and the
Shareholders (if the dispute is resolved by them or the Statement of Final Per
Share Amounts otherwise becomes final pursuant hereto without referral to the
Accountants) or the Accountants (if a dispute is resolved by them) shall set
forth such resolution in writing and such writing shall (i) set forth the Final
Outstanding Common Stock Number, the Final Per Share Cash Amount, the Final Per
Share Common Stock Amount and the Total Consideration and (ii) be final,
conclusive and binding for purposes of this Agreement.

          1.9.5  Final Determination. Within 10 business days following the
                 -------------------   
final determination of the Final Outstanding Common Stock Number, the Final Per
Share Cash Amount, the Final Per Share Common Stock Amount and the Total
Consideration as provided in this Section 1.9, (i) the Parent shall deliver to
each Shareholder (a) the cash amount, if any, by which the aggregate of the
Final Per Share Cash Amounts payable to such Shareholder, as finally determined
pursuant hereto, exceeds the aggregate of the Closing Per Share Cash Amounts
paid to such Shareholder at the Closing; and (b) the number of shares of Parent
Common Stock, if any, by which the aggregate of the Final Per Share Common Stock
Amounts

                                      -5-
<PAGE>
 
deliverable to such Shareholder, as finally determined pursuant hereto, exceeds
the aggregate of the Closing Per Share Common Stock Amounts delivered to such
Shareholder at the Closing; or (ii) each Shareholder shall deliver to the Parent
(a) the cash amount, if any, by which the aggregate of the Closing Per Share
Cash Amounts paid to such Shareholder at the Closing exceeds the aggregate of
the Final Per Share Cash Amounts payable to such Shareholder as finally
determined pursuant hereto; and (b) the number of shares of Parent Common Stock,
if any, by which the aggregate of the Closing Per Share Common Stock Amounts
delivered to such Shareholder at the Closing exceeds the aggregate of the Final
Per Share Common Stock Amounts deliverable to such Shareholder as finally
determined pursuant hereto.

          1.9.6  Expenses.  The Parent and the Shareholders shall each pay their
                 --------                                                       
own costs incurred in connection with this Section 1.9, including the fees and
expenses of their respective attorneys and accountants, if any.

                      2.   REPRESENTATIONS AND WARRANTIES
                      OF THE COMPANY AND THE SHAREHOLDERS

     The Company and each Shareholder, severally and not jointly, hereby
represent and warrant to the Parent and Merger Sub as follows:

     2.1  Exhibit 2.  The statements in Exhibit 2 attached hereto are true and
          ---------                                                           
correct.

     2.2  Stock Ownership.  Such Shareholder owns, beneficially and of record,
          ---------------                                                     
with full power to vote, the number of shares of Company Common Stock set forth
beside such Shareholder's name on Exhibits Exhibit 2.2 and such shares are so
held by such Shareholder free and clear of all liens, encumbrances and adverse
claims whatsoever.

     2.3  Authority.  Such Shareholder has full right, power, legal capacity and
          ---------                                                             
authority to (i) execute, deliver and perform this Agreement, and all other
documents and instruments referred to herein or contemplated hereby to be
executed, delivered and performed by such Shareholder (each a "Shareholder
                                                               -----------
Related Document") and (ii) consummate the transactions contemplated herein and
----------------                                                               
thereby.  This Agreement has been duly executed and delivered by such
Shareholder and constitutes, and any Shareholder Related Document, when duly
executed and delivered by such Shareholder named as a party therein will
constitute, legal, valid and binding obligations of such Shareholder enforceable
against such Shareholder in accordance with their respective terms and
conditions, except as such enforcement may be limited by bankruptcy, insolvency,
reorganization, moratorium or other similar laws affecting the enforcement of
creditors' rights generally and by general principles of equity (whether applied
in a proceeding at law or in equity).

     2.4  Consents.  No approval, consent, order or action of or filing with any
          --------                                                              
court, administrative agency, governmental authority or other third party is
required for the execution, delivery or performance by such Shareholder of this
Agreement or any Shareholder Related Document.  The execution, delivery and
performance by such Shareholder of this Agreement and any Shareholder Related
Documents do not violate any mortgage, indenture, contract, agreement, lease or
commitment or other instrument of any kind to which such Shareholder is a party
or by which such Shareholder or such Shareholder's assets or properties may be
bound or affected or any law, rule or regulation applicable to such Shareholder
or any court injunction, order or decree or any valid and enforceable order of
any governmental agency in effect as of the date hereof having jurisdiction over
such Shareholder.

                                      -6-
<PAGE>
 
                      3.  REPRESENTATIONS AND WARRANTIES
                         OF THE PARENT AND MERGER SUB

      3.1 Representations and Warranties.  The Parent hereby represents and
          ------------------------------                                   
warrants to the Shareholders and the Company as follows:

          3.1.1  Organization.  The Parent is a corporation duly organized,
                 ------------                                              
validly existing and in good standing under the laws of the State of Texas.  The
Parent is duly qualified or licensed as a foreign corporation authorized to do
business in all states in which any of its assets or properties may be situated
or where its business is conducted except where the failure to obtain such
qualification or license would not have a Parent Material Adverse Effect (as
defined below).

          3.1.2  Capitalization of the Parent.  The total authorized, issued and
                 ----------------------------                                   
outstanding capital stock of the Parent is as set forth in the Confidential
Information Statement dated August __, 1997.  The outstanding shares of the
capital stock of Parent have been duly and validly issued and are fully paid and
non-assessable.

          3.1.3  Authority.  The Parent has the requisite power and authority to
                 ---------                                                      
execute, deliver and perform this Agreement and all documents and instruments
referred to herein or contemplated hereby (the "Parent Related Documents") and
                                                ------------------------      
to consummate the transactions contemplated herein and thereby.  This Agreement
has been duly executed and delivered by the Parent and constitutes, and all the
Parent Related Documents, when executed and delivered by the Parent will
constitute, legal, valid and binding obligations of the Parent, enforceable in
accordance with their respective terms and conditions except as such enforcement
may be limited by bankruptcy, insolvency, reorganization, moratorium or other
similar laws affecting the enforcement of creditors' rights generally and by
general principles of equity (whether applied in a proceeding at law or in
equity).

          3.1.4  Consents.  Except as provided on Exhibits Exhibit 3.1.4, no
                 --------                                                   
approval, consent, order or action of or filing with any court, administrative
agency, governmental authority or other third party is required for the
execution, delivery or performance by the Parent of this Agreement or the Parent
Related Documents or the consummation by the Parent of the transactions
contemplated hereby, except for (i) the filing of the Parent's registration
statement with respect to the IPO ("Registration Statement") with the U.S.
                                    ----------------------                
Securities and Exchange Commission ("SEC") pursuant to the Securities Act and
                                     ---                                     
the SEC's declaration of effectiveness of such Registration Statement and the
completion of all necessary filings required under, and the obtaining of all
necessary consents and approvals required pursuant to, state securities or "blue
sky" laws in connection with the IPO, and (ii) the filing of the Articles of
Merger with the Secretary of State of Minnesota.

          3.1.5  Defaults. The Parent is not in default under or in violation
                 --------      
of, and the execution, delivery and performance of this Agreement and the Parent
Related Documents and the consummation by the Parent of the transactions
contemplated hereby and thereby will not result in a default under or in
violation of (i) any mortgage, indenture, charter or bylaw provision, contract,
agreement, lease, commitment or other instrument of any kind to which the Parent
is a party or by which the Parent or any of its properties or assets may be
bound or affected or (ii) any law, rule or regulation applicable to the Parent
or any court injunction, order or decree, or any valid and enforceable order of
any governmental agency in effect as of the date hereof having jurisdiction over
the Parent, which default or violation prevents the Parent from 

                                      -7-
<PAGE>
 
consummating the transactions contemplated hereby or is reasonably likely to
have a Parent Material Adverse Effect.

     3.1.6     Investment Company.  The Parent is not an "investment company" or
               ------------------                                               
a company "controlled" by an "investment company" within the meaning of the
Investment Company Act of 1940, as amended, or a "holding company," a
"subsidiary company" of a "holding company" or an "affiliate" of a "holding
company" or a "public utility" within the meaning of the Public Utility Holding
Company Act of 1935, as amended.

     3.1.7     Financial Statements.  The Parent has provided certain financial
               --------------------                                            
statements to the Shareholders ("Parent Financial Statements") and such Parent
                                 ---------------------------                  
Financial Statements have been prepared in accordance with GAAP and fairly
present the consolidated financial position, results of operations and cash
flows of the Parent and its then existing consolidated subsidiaries as of the
dates and for the periods indicated, subject to normal year-end adjustments and
any other adjustments described therein or in the notes or schedules thereto.
The books and records of the Parent have been kept in reasonable detail and
accurately and fairly reflect the transactions of the Parent.

     3.1.8     Taxes.  The Parent has either accrued, discharged or caused to be
               -----                                                            
discharged, as the same have become due, or the Parent Financial Statements
contain adequate accruals and reserves for, all taxes, interest thereon, fines
and penalties of every kind and character, attributable or relating to the
properties and business of the Parent for the period ended covered by the Parent
Financial Statements.

     3.1.9     Full Authority.  The Parent has the corporate power and authority
               --------------                                                   
and has obtained all licenses, permits, qualifications, and other documentation
(including permits required under applicable Environmental Law, as defined in
Exhibit 2) necessary to own and/or operate its businesses, properties and assets
and to carry on its businesses as being conducted on the date of this Agreement,
except such licenses, permits, qualifications or other documentation, the
failure to obtain which is not reasonably likely to result in a Parent Material
Adverse Effect, and such businesses are now being conducted and such assets and
properties are being owned and/or operated in compliance with all applicable
laws (including Environmental Law), ordinances, rules and regulations of any
governmental agency of the United States, any state or political subdivision
thereof, or any foreign jurisdiction, all applicable court or administrative
agency decrees, awards and orders and all such licenses, permits, qualifications
and other documentation, except where the failure to comply will not have a
Parent Material Adverse Effect, and there is no existing condition or state of
facts that would give rise to a violation thereof or a liability or default
thereunder that is reasonably likely to have a Parent Material Adverse Effect.

     3.1.10    Access.  The Parent has cooperated fully in permitting the
               ------                                                    
Shareholders and their representatives to make a full investigation of the
properties, operations and financial condition of the Parent and has afforded
the Shareholders and their representatives reasonable access to the offices,
buildings, real properties, machinery and equipment, inventory and supplies,
records, files, books of account, tax returns, agreements and commitments and
personnel of Parent.

     3.1.11    Disclosure.  No representation or warranty by the Parent in this
                ----------                                                      
Agreement, and no statement contained in any certificate delivered by the Parent
to the Shareholders pursuant to this Agreement, contains any untrue statement of
a material fact or omits any material fact necessary in order to make the

                                      -8-
<PAGE>
 
statements herein or therein, in light of the circumstances under which they are
or were made, not misleading.

       3.1.12 Parent Material Adverse Effect.  The term "Parent Material
              ------------------------------             ---------------
Adverse Effect" shall mean an adverse effect on the properties, assets,
--------------                                                         
financial position, results of operations, long-term debt, other indebtedness,
cash flows or contingent liabilities of the Parent and its consolidated
subsidiaries, taken as a whole, in an amount of $100,000 or more.

       3.1.13 Tax-Free Reorganization.  With respect to the qualification of
              -----------------------                                       
the Merger as a reorganization within the meaning of Section 368(a) of the Code:

       (i)    The Parent has no plan or intention to sell, exchange or otherwise
     dispose or liquidate the Surviving Corporation, to merge the Surviving
     Corporation with or into any other corporation, to sell or otherwise
     dispose of its Surviving Corporation Common Stock except for transfers of
     Surviving Corporation Common Stock to corporations of which the Parent has
     control (within the meaning of Section 368(a) of the Code) at the time of
     such transfer, or to cause the Surviving Corporation to sell or otherwise
     dispose of any of its assets or of any assets acquired in the Merger,
     except for dispositions made in the ordinary course of business or
     transfers of assets to a corporation of which the Surviving Corporation has
     control (within the meaning of Section 368(a) of the Code) at the time of
     such transfer.

       (ii)   The Parent has no plan or intention to cause the Surviving
     Corporation, after the Merger, to issue additional shares of its stock that
     would result in the Parent losing control of the Surviving Corporation
     within the meaning of Section 368(c) of the Code.

       (iii)  Following the Merger, the Surviving Corporation will continue the
     Company's historic business or use a significant portion of its historic
     business assets in a business.

       (iv)   Except as provided in Section 8.20 below, if the Merger is
     effected, the Parent and Merger Sub will each pay their respective
     expenses, if any, incurred in connection with the Merger.

       (v)    The Parent Common Stock that will be issued in connection with the
     Merger is voting stock within the meaning of Section 368(c) of the Code.

       (vi)   At the Effective Time, neither the Parent nor Merger Sub will
     have any outstanding warrants, options, convertible securities, or any
     other right pursuant to which any person could acquire stock in the Parent
     or Merger Sub which, if exercised or converted, would affect the Parent's
     acquisition or retention of control of the Surviving Corporation.

       (vii)  Neither the Parent nor Merger Sub is an investment company as
     defined in Section 368(a)(2)(F) of the Code.

       (viii) None of the Parent Common Stock received by the Shareholders as a
     part of the Final Merger Consideration will be separate consideration for,
     or allocable to, any employment agreement.

                                      -9-
<PAGE>
 
               (ix)      Neither the Parent nor Merger Sub is under the
     jurisdiction of a court in a case under Title 11 of the United States Code,
     or a receivership, foreclosure, or similar proceeding in a federal or state
     court.

               3.1.14    Value of Parent Common Stock. The price used to
                         ----------------------------
determine the value of the Parent Common Stock as part of the Total
Consideration shall be the same for each shareholder of each company that will
be acquired by the Parent at the IPO.

          3.2  Representations and Warranties Concerning the Merger Sub. The
               --------------------------------------------------------
Parent and Merger Sub, jointly and severally, hereby represent and warrant to
the Shareholders and the Company as follows:

               3.2.1     Organization and Standing. Merger Sub is a corporation
                         -------------------------
duly incorporated, validly existing and in good standing under the laws of the
State of Minnesota.

               3.2.2     Capital Structure. The authorized capital stock of
                         -----------------
Merger Sub consists of 5,000 shares of common stock, par value $.01 per share,
1,000 of which are validly issued and outstanding, fully paid and nonassessable
and are owned by the Parent free and clear of all liens, encumbrances and
adverse claims.

               3.2.3     Authority. Merger Sub has the corporate power and
                         ---------
authority to execute, deliver and perform this Agreement and to consummate the
transactions contemplated hereby. The execution and delivery of this Agreement,
the performance by Merger Sub of its obligations hereunder and the consummation
of the transactions contemplated hereby have been duly authorized by its Board
of Directors and the Parent as its sole shareholder, and, except for the
corporate filings required by state law, no other corporate proceedings on the
part of Merger Sub are necessary to authorize this Agreement and the transaction
contemplated hereby. This Agreement has been duly and validly executed and
delivered by Merger Sub and (assuming the due authorization, execution and
delivery hereof by the Company) constitutes a valid and binding obligation of
Merger Sub enforceable against Merger Sub in accordance with its terms, except
as such enforcement may be limited by bankruptcy, insolvency, reorganization,
moratorium or other similar laws affecting the enforcement of creditors' rights
generally and by general principles of equity (whether applied in a proceeding
at law or in equity).

          4.  CERTAIN COVENANTS, AGREEMENTS AND PRE-CLOSING MATTERS

     4.1       Agreements of the Shareholders to be Effective Upon Closing.
               -----------------------------------------------------------  
Effective upon Closing, and without further action on the part of any party or
other person, the Shareholders covenant and agree as follows:

               4.1  Covenant Not to Compete.
                    ----------------------- 

               (i)   For the considerations specified in this Agreement and in
     recognition that the covenants by the Shareholders in this Section are a
     material inducement to the Parent to enter into and perform this Agreement,
     each Shareholder agrees that for the period from the Closing Date to the
     later to occur of (a) the date which is five years after the Closing Date
     or (b) the date which is two years following any termination of such
     Shareholder's employment with the Company, such Shareholder will not
     represent, engage in, carry on, or have a financial interest in, directly
     or 

                                     -10-
<PAGE>
 
     indirectly, individually, as a member of a partnership or limited
     liability company, equity owner, shareholder (other than as a shareholder
     of less than one percent of the issued and outstanding stock of a publicly-
     held company whose gross assets exceed $100 million), investor, officer,
     director, trustee, manager, employee, agent, associate or consultant engage
     in any business that involves indoor air quality, heating, ventilation, air
     conditioning, appliance, mechanical construction or sewer cleaning products
     or services within a 100-mile radius of the city of Minneapolis, Minnesota;
     provided, however, that if John Deblon's employment is terminated without
     Cause (as such term is defined in that certain Employment Agreement between
     the Company and John Deblon dated as of the Closing), John Deblon's non-
     compete period in Section 4.1.1(i)(b) shall be reduced to one year.

               (ii)  Each Shareholder agrees that the limitations set forth
     herein on such Shareholder's rights to compete with the Parent and its
     affiliates as set forth in clause (i) are reasonable and necessary for the
     protection of Parent and its affiliates. In this regard, each Shareholder
     specifically agrees that the limitations as to period of time and
     geographic area, as well as all other restrictions on such Shareholder's
     activities specified herein, are reasonable and necessary for the
     protection of the Parent and its affiliates. Each Shareholder agrees that,
     in the event that the provisions of this Section should ever be deemed to
     exceed the scope of business, time or geographic limitations permitted by
     applicable law, such provisions shall be and are hereby reformed to the
     maximum scope of business, time or geographic limitations permitted by
     applicable law.

               (iii) Each Shareholder agrees that the remedy at law for any
     breach by such Shareholder of this Section 4.1.1 will be inadequate and
     that the Parent shall be entitled to injunctive relief.

               4.1.2  Release. Effective as of the Effective Time, each
                      -------
Shareholder does hereby (i) release, acquit and forever discharge the Surviving
Corporation from any and all liabilities, obligations, claims, demands, actions
or causes of action arising from or relating to any event, occurrence, act,
omission or condition occurring or existing on or prior to the Effective Time,
including, without limitation, any claim for indemnity or contribution from the
Surviving Corporation in connection with the obligations or liabilities of such
Shareholder hereunder, except for salary and benefits payable to such
Shareholder as an employee in the ordinary course of business; (ii) waive all
breaches, defaults or violations of any agreement applicable to the Company
Common Stock and agree that any and all such agreements are terminated as of the
Effective Time, and (iii) waive any and all preemptive or other rights to
acquire any shares of capital stock of the Company and release any and all
claims arising in connection with any prior default, violation or failure to
comply with or satisfy any such preemptive or other rights.

     4.2  Elimination of Expense.  Prior to Closing, the Shareholders will
          ----------------------                                          
produce evidence to the satisfaction of the Parent and its lenders that the
expenses of the Company as generally described in that certain letter from the
Shareholders to the Parent dated August ___, 1997, have been eliminated as
expenses of the Surviving Corporation as of and following the Closing Date.

     4.3  Deferred Compensation Plans.  Prior to Closing, the Shareholders will
          ---------------------------                                          
cause all current or future obligations of the Company under the split dollar
life and other deferred compensation plans covering any Shareholder or any
employee of the Company to be satisfied in full (including current or deferred
tax liabilities arising therefrom) all in accordance with the provisions of
Exhibits Exhibit 4.3 attached hereto.

                                     -11-
<PAGE>
 
     4.4  Audit.  Prior to Closing, the Accountants shall complete an audit of
          -----                                                               
the Company for the fiscal year ended March 31, 1997 and for the period from
such date through June 30, 1997, and such additional audit and/or review work as
may be requested by the Parent through and including the Closing Date and
provide its report to the Parent and the Shareholders.

     4.5  Certain Payables and Receivables.  On or prior to Closing, the
          --------------------------------                              
Shareholders shall cause to be paid in full in cash all accounts receivable,
notes receivable and advances payable by any Shareholder to the Company and the
Company shall pay in full in cash all accounts payable, notes payable (except
any Tax Notes (as defined) which shall be paid according to their terms) and
advances payable by the Company to any Shareholder.

     4.6  Pre-Closing Covenants and Agreements.  The Shareholders, each
          ------------------------------------                         
severally and not jointly, and the Company agree as set forth in Exhibits
Exhibit 4.6  attached hereto.

     4.7  Confidentiality.  Prior to the Effective Time, none of the Parent,
          ---------------                                                   
Merger Sub, the Company or the Shareholders will disclose the terms of this
Agreement or the Merger to any person other than their respective directors,
officers, agents or representatives, except as otherwise provided herein or
unless required by law.  The Company may make appropriate disclosures of the
general nature of the Merger to its employees, vendors and customers to protect
the Company's goodwill and to facilitate the Closing.  The Parent and Merger Sub
may disclose pertinent information regarding the Merger to its existing and
prospective investors, lenders, or investment bankers or financial advisors for
the purpose of obtaining financing, including, without limitation, financing
related to the IPO or other offerings of its securities, and may describe this
Agreement and the transactions contemplated hereby in any registration statement
filed by the Parent under the Securities Act and in reports filed by the Parent
under the Securities Exchange Act of 1934, and may file this Agreement as an
exhibit to any thereof.  The Parent may also make appropriate disclosures of the
general nature of the Merger and the identity, nature and scope of the Company's
operations to prospective acquisition candidates in connection with the Parent's
efforts to effect additional acquisitions.  Each party will have mutual approval
rights with respect to written employee presentations concerning the prospective
merger.

     4.8  Tax-Free Reorganization.  Unless the other parties shall otherwise
          -----------------------                                           
agree in writing, none of the Shareholders, the Parent, Merger Sub, the Company
or the Surviving Corporation shall knowingly take or fail to take any action,
that would jeopardize the qualification of the Merger as a reorganization
withing the meaning of Section 368(a) of the Code.

     4.9  Company Plans.  Except as otherwise contemplated by this Agreement,
          -------------                                                      
the Company Plans (as defined in Exhibit 2) described on Exhibits Exhibit 4.9 in
effect at the date of this Agreement will remain in effect unless otherwise
determined by the Parent after the Effective Time.

     4.10 Purchase of Certain Receivables.  If any accounts receivable included
          -------------------------------                                      
in current assets of the Company for purposes of determining Working Capital (as
defined in Exhibit 1) remain unpaid in full on the date that is 60 days
following the Closing, the Shareholders shall, upon written request by the
Surviving Corporation made on or before the date that is 90 days following the
Closing, purchase the same from the Surviving Corporation, without recourse, for
the uncollected amount thereof (net of any reserve for bad debts on the books of
the Company on the Closing).

                                     -12-
<PAGE>
 
     4.11 Income Tax Distribution.  At or prior to the Closing, the Shareholders
          -----------------------                                               
shall cause the Company to pay to the Shareholders as a dividend and as a
distribution of accumulated S Corporation earnings of all tax periods through
the Effective Time a cash amount, which may be reasonably estimated, equal to
the net taxable income of the Company as determined for Federal income tax
purposes for the Company as an S Corporation less any prior distributions made
by the Company to the Shareholders with respect to such earnings ("Cash Tax
                                                                   --------
Distribution").  In the event that there is insufficient cash of the Company to
------------                                                                   
make the Cash Tax Distribution either in whole or in part, the Company may issue
short term notes payable to the Shareholders in amounts equal to the amount of
the Cash Tax Distribution less the amount of cash actually distributed to the
Shareholders as part of the Cash Tax Distribution ("Tax Notes") in the form of
                                                    ---------                 
Exhibit 4.11.  The Tax Notes, if issued, shall (i) be issued prior to the
Effective Time, (ii) bear interest at a rate not to exceed six percent (6%) per
annum, (iii) provide that the principal and all accrued interest shall be due
and payable six (6) months after the date of the Tax Notes, and (iv) impose no
prepayment penalty.  All cash payments of the Cash Tax Distribution and all
amounts of any Tax Notes shall be deducted from the cash portion of the Total
Consideration.

                 5.  CONDITIONS PRECEDENT; CLOSING DELIVERIES

     5.1  Conditions Precedent to the Obligations of the Parent and Merger Sub.
          --------------------------------------------------------------------  
The obligations of the Parent and Merger Sub to effect the Merger under this
Agreement are subject to the satisfaction of each of the following conditions,
unless waived by the Parent in writing to the extent permitted by applicable
law:

          5.1.1  Accuracy of Representations and Warranties. The representations
                 ------------------------------------------
and warranties of the Shareholders and the Company contained in this Agreement,
in Exhibit 2 and the Disclosure Schedule referred to therein and the other
Exhibits provided by the Shareholders or the Company pursuant to this Agreement
or in any closing certificate or document delivered to the Parent pursuant
hereto shall be true and correct at and as of the Closing Date as though made at
and as of that time other than such representations and warranties as are
specifically made as of another date, and the Shareholders and the Company shall
each have delivered to the Parent and Merger Sub a certificate to that effect.

          5.1.2  Performance of Covenants. The Shareholders and the Company
                 ------------------------
shall have performed and complied with all covenants of this Agreement to be
performed or complied with by them at or prior to the Closing Date, and the
Shareholders and the Company shall each have delivered to the Parent and Merger
Sub a certificate to that effect.

          5.13   Legal Actions or Proceedings.  No legal action or proceeding
                 ----------------------------                                
shall have been instituted after the date hereof against the Company or against
the Parent or Merger Sub arising by reason of the acquisition of the Company
pursuant to this Agreement, which is reasonably likely (i) to restrain, prohibit
or invalidate the consummation of the transactions contemplated by this
Agreement, (ii) to have a Company Material Adverse Effect or (iii) to have a
Parent Material Adverse Effect after giving effect to the consummation of the
transactions contemplated by this Agreement, and the Shareholders and the
Company shall each have delivered to the Parent and Merger Sub a certificate to
that effect.

          5.1.4  Approvals. The Company and the Shareholders shall have procured
                 ---------
all of the consents, approvals and waivers of third parties or any regulatory
body or authority, whether required contractually or by applicable law or
otherwise necessary for the execution, delivery and performance of this
Agreement (including the Company Related Documents and the Shareholder Related
Documents) by the 

                                     -13-
<PAGE>
 
Company and the Shareholders prior to the Closing Date, and the Shareholders and
the Company shall each have delivered to the Parent and Merger Sub a certificate
to that effect.

          5.1.5   Closing Deliveries.  All documents required to be executed or
                  ------------------                                           
delivered at Closing by the Shareholders pursuant to Section 5.3 of this
Agreement shall have been so executed and delivered.

          5.1.6   No Casualty, Loss or Damage. No casualty, loss or damage shall
                  ---------------------------
have occurred on or prior to the Effective Time to any of the properties or
assets of the Company.

          5.1.7   Licenses, etc. The Company shall have obtained all such
                  -------------
licenses and permits as are legally required for the continued operation of the
business after the Effective Time, except such licenses and permits, the absence
of which will not have a Company Material Adverse Effect.

          5.1.8   No Material Adverse Change.  Since March 31, 1997, there shall
                  --------------------------                                    
not have been any event that in the reasonable judgment of the Parent adversely
affects the properties, assets, financial condition, results of operations, cash
flows, businesses or prospects of the Company.

          5.1.9   IPO. The Parent shall have completed the IPO on terms
                  ---
acceptable to it, and the net proceeds thereof shall have been received by the
Parent.

          5.1.10  Certain Corporate Actions.  All necessary director and
                  -------------------------                             
shareholder resolutions, waivers and consents required to consummate the
transactions contemplated hereunder shall have been executed and delivered.

     5.2  Conditions Precedent to the Obligations of the Shareholders and the
          -------------------------------------------------------------------
Company.  The obligations of the Shareholders and the Company under this
-------                                                                 
Agreement are subject to the satisfaction of each of the following conditions,
unless waived by the Shareholders and the Company in writing to the extent
permitted by applicable law:

          5.2.1   Accuracy of Representations and Warranties. The
                  ------------------------------------------
representations and warranties of the Parent and Merger Sub contained in this
Agreement or in any closing certificate or document delivered to the
Shareholders or the Company pursuant hereto shall be true and correct on and as
of the Closing Date as though made at and as of that date other than such
representations and warranties as are specifically made as of another date, and
the Parent and Merger Sub shall have delivered to the Shareholders and the
Company a certificate to that effect.

          5.2.2   Performance of Covenants. The Parent and Merger Sub shall have
                  ------------------------
performed and complied with all covenants of this Agreement to be performed or
complied with by them at or prior to the Closing Date and the Parent and Merger
Sub shall have delivered to the Shareholders and the Company a certificate to
such effect.

          5.2.3   Approvals. The Parent shall have procured all of the consents,
                  ---------
approvals and waivers specified in Exhibit 3.1.4 prior to the Closing Date, and
the Parent shall have delivered to the Shareholders and the Company a
certificate to that effect.

                                     -14-
<PAGE>
 
          5.2.4  Closing Deliveries.  All documents required to be executed or
                 ------------------                                           
delivered at Closing by the Parent pursuant to Section 5.4 of this Agreement
shall have been so executed and delivered.

     5.3  Deliveries by the Shareholders at the Closing.  At the Closing,
          ---------------------------------------------                  
simultaneously with the deliveries by the Parent specified in Section 5.4 below,
and in addition to any deliveries required to be made by the Shareholders and
the Company pursuant to any other transaction document at the Closing, the
Shareholders shall deliver or cause to be delivered to the Parent the following:

          5.3.1   Closing Certificates.  The Shareholders and the Company shall
                  --------------------                                         
deliver the certificates required pursuant to Sections 5.1.1, 5.1.2, 5.1.3 and
5.1.4.

          5.3.2   Stock Transfer Restriction Agreement.  The Shareholders shall
                  ------------------------------------                         
execute and deliver and shall cause the Shareholders to execute and deliver a
Stock Transfer Restriction Agreement on the Closing Date, effective as of the
Effective Time, substantially in the form set forth in Exhibits Exhibit 5.3.2.

          5.3.3   Employment Agreements.  Each Shareholder and certain other
                  ---------------------                                     
employees of the Company specified on Exhibits Exhibit 5.3.3 shall execute and
deliver an Employment Agreement (with the insertion of the appropriate Section
7(b) based on whether such Shareholder or any such employee is designated an
"Executive or Key Employee" or "Manager" on Exhibit 5.3.3 and with the blanks
appropriately completed as set forth in a confidential letter between the
Company and the Parent) with the Company on the Closing Date, effective as of
the Effective Time, substantially in the form set forth in Exhibits Exhibit
5.3.3A.

          5.3.4   Lease Agreement. The Shareholders shall cause the owner of the
                  ---------------
property located at 9649 Girard Avenue South, Minneapolis, Minnesota 55431, to
execute and deliver a lease agreement with the Company substantially in the form
attached as Exhibits Exhibit 5.3.4.

          5.3.5   Registration Rights Agreement.  The Shareholders shall execute
                  -----------------------------                                 
and deliver and shall cause the Shareholders to execute and deliver a
Registration Rights Agreement at the Closing, effective as of the Effective
Time, substantially in the form set forth in Exhibits Exhibit 5.3.5 attached
hereto.

          5.3.6   Opinion of Counsel for the Shareholders and the Company.  The
                  -------------------------------------------------------      
Shareholders shall deliver the favorable opinion of  Faegre & Benson, counsel to
the Shareholders and the Company, dated the Effective Time, substantially in the
form and to the effect set forth in Exhibit 5.3.6 attached hereto.

          5.3.7   Documents, Stock Certificates.  The Shareholders shall execute
                  -----------------------------                                 
and deliver, and shall cause the Company and the Shareholder to execute and
deliver, the documents, certificates, opinions, instruments and agreements
required to be executed and delivered by the Company or its officers or
directors or the Shareholders at the Closing as contemplated hereby or as may be
reasonably requested by the Parent and shall deliver or cause to be delivered
the documents and evidence required under Section 4.  Stock Certificates
representing all of the outstanding Company Common Stock and properly executed
and completed letters of transmittal shall be delivered by the Shareholders to
the Parent.

          5.3.8   Discharge of Indebtedness, Releases, Etc.  The indebtedness of
                  ----------------------------------------                      
the Company referred to in Exhibits Exhibit 5.3.8 attached hereto ("Terminated
                                                                    ----------
Obligations") shall be paid in full or refinanced on terms acceptable to the
-----------                                                                 
Parent, and the Shareholders shall cause all holders of any such Terminated
Obligations to deliver to the Parent, in form reasonably satisfactory to the
Parent and the lenders to the Parent 

                                     -15-
<PAGE>
 
or Merger Sub, such customary releases, termination statements, consents,
approvals or other documents or instruments required, in the judgment of the
Parent, to release and terminate all liens, security interests, claims, or
rights of such holders against the Surviving Corporation or the Parent or any of
their respective assets in connection therewith.

          The consummation of the Closing shall not be deemed to be a waiver by
the Parent or the Surviving Corporation of any of their rights or remedies
against the Shareholders hereunder for any breach of warranty, covenant or
agreement by the Company or the Shareholders herein irrespective of any
knowledge of or investigation made by or on behalf of the Parent or Merger Sub;
provided, however, that if the Company shall disclose in writing to the Parent
prior to the Closing Date a specified breach of a specifically identified
representation, warranty, covenant or agreement of the Company or any
Shareholder herein by the Company or any Shareholder, and requests a waiver
thereof by the Parent, and the Parent shall waive any such specifically
identified breach in writing prior to the Closing Date, the Parent and the
Surviving Corporation, for themselves and for each Parent Indemnified Party (as
defined below) shall be deemed to have waived their respective rights and
remedies hereunder for, and the Shareholders shall have no liability with
respect to, any such specifically identified breach, to the extent so identified
by the Company and so waived by the Parent.

     5.4  Deliveries by the Parent at the Closing.  At the Closing,
          ---------------------------------------                  
simultaneously with the deliveries by the Shareholders specified in Section 5.3
above, and in addition to any other deliveries to be made by the Parent and
Merger Sub pursuant to any other transaction document at the Closing, the Parent
shall deliver or cause to be delivered to the Shareholders the following:

          5.4.1   Closing Certificates.  The Parent and Merger Sub shall deliver
                  --------------------                                          
the certificates required pursuant to Sections 5.2.1, 5.2.2 and 5.2.3.

          5.4.2   Registration Rights Agreement.  The Parent shall execute and
                  -----------------------------                               
deliver to the Shareholders a Registration Rights Agreement at the Closing,
effective as of the Effective Time, substantially in the form set forth in
Exhibit 5.3.5.

          5.4.3  Opinion of Counsel for the Parent and Merger Sub.  The Parent
                 ------------------------------------------------             
shall deliver the favorable opinion of its legal counsel dated the Effective
Time, substantially in the form and to the effect set forth in Exhibits Exhibit
5.4.3.

           5.4.4  Closing Merger Consideration.  The Parent shall deliver the
                  ----------------------------                               
Closing Merger Consideration to the Shareholders.

          The consummation of the Closing shall not be deemed to be a waiver by
the Shareholders of any of their rights or remedies hereunder for breach of any
warranty, covenant or agreement herein by the Parent or Merger Sub irrespective
of any knowledge of or investigation with respect thereto made by or on behalf
of any Shareholder; provided, however, that if the Parent shall disclose in
writing to the Shareholders prior to the Closing a specified breach of a
specifically identified representation, warranty, covenant or agreement of the
Parent or Merger Sub contained herein by the Parent or Merger Sub, and requests
a waiver thereof by the Company and the Shareholders, and the Company and the
Shareholders shall waive any such specifically identified breach in writing
prior to the Closing, the Company and the Shareholders shall be deemed to have
waived their rights and remedies hereunder for, and the Parent and Merger Sub
shall have 

                                     -16-
<PAGE>
 
no liability or obligation to the Shareholders or the Company with respect to,
any such specifically identified breach, to the extent so identified by the
Parent and waived by the Company and the Shareholders.

                         6. SURVIVAL, INDEMNIFICATIONS

     6.1  Survival.  The representations and warranties set forth in this
          --------                                                       
Agreement and the other documents, instruments and agreements contemplated
hereby shall survive after the date hereof to the extent provided herein.  The
representations and warranties of the Shareholders and the Company herein and in
the Shareholder Related Documents and the Company Related Documents (as defined
in Exhibit 2) other than those of the Shareholders and the Company in Sections
2.2, 2.3, 2.4 and in Sections 2, 3, 6, 12 and 18(ii), (iii), (iv), (v), (vi) and
(vii) of Exhibit 2 shall survive for a period of 36 months after the Closing
Date and the representations and warranties of the Shareholders and the Company
contained in Sections 2.2, 2.3, 2.4 and in Sections 2, 3, 6, 12 and 18(ii),
(iii), (iv), (v), (vi) and (vii)  of Exhibit 2 shall survive for the maximum
period permitted by applicable law.  The representations and warranties of the
Parent herein and in the Parent Related Documents, other than those in Sections
3.1.3 and 3.1.4, shall survive for a period of 36 months after the Closing Date
and the representations and warranties of the Parent contained in Sections 3.1.3
and 3.1.4 shall survive for the maximum period permitted by applicable law.  The
periods of survival of the representations and warranties as stated above in
this Section 6.1 are referred to herein as the "Survival Period." The
                                                ---------------      
liabilities of the parties under their respective representations and warranties
shall expire as of the expiration of the applicable Survival Period and no claim
for indemnification may be made with respect to any breach of any representation
or warranty, the applicable Survival Period of which shall have expired, except
to the extent that written notice of such breach shall have been given to the
party against which such claim is asserted on or before the date of such
expiration.  The covenants and agreements of the parties herein (including but
not limited to Exhibit 4.6) and in other documents and instruments executed and
delivered in connection with the closing of the transactions contemplated hereby
shall survive for the maximum period permitted by law.

     6.2  Indemnification.
          --------------- 

          6.2.1   Parent Indemnified Parties.  Subject to the provisions of
                  --------------------------                               
Sections 6.1 and 6.3 hereof, the Shareholders, severally and not jointly, shall
indemnify, save and hold harmless the Parent, the Surviving Corporation, Merger
Sub and any of their assignees (including lenders) and all of their respective
officers, directors, employees, representatives, agents, advisors and
consultants and all of their respective heirs, legal representatives, successors
and assigns (collectively the "Parent Indemnified Parties") from and against any
                               --------------------------                       
and all damages, liabilities, losses, loss of value (including the value of
adverse effects on cash flow or earnings), claims, deficiencies, penalties,
interest, expenses, fines, assessments, charges and costs, including reasonable
attorneys' fees and court costs (collectively "Losses") arising from, out of or
                                               ------                          
in any manner connected with or based on:

          (i)     the breach of any covenant of the Shareholders or the Company
     or the failure by the Shareholders or the Company to perform any obligation
     of the Shareholders or the Company contained herein or in any Company
     Related Document or Shareholder Related Document;

          (ii)    any inaccuracy in or breach of any representation or warranty
     of the Shareholders contained herein or in any Shareholder Related
     Document;

                                     -17-
<PAGE>
 
          (iii)   any inaccuracy in or breach of any representation or warranty
     of the Company contained herein or in any Company Related Document;

          (iv)    indemnification payments made by the Company or the Surviving
     Corporation to the Company's present or former officers, directors,
     employees, agents, consultants, advisors or representatives in respect of
     actions taken or omitted to be taken prior to the Closing; and

          (v)     any act, omission, occurrence, event, condition or
     circumstance occurring or existing at any time on or before the Effective
     Time and involving or related to the assets, properties, business or
     operations now or previously owned or operated by the Company and not (a)
     disclosed with reasonable specificity in the Disclosure Schedule or (b)
     disclosed in the Company Financial Statements (as defined in Exhibit 2) or
     in working capital or long term debt (in each case as determined for
     purposes of calculating the Final Merger Consideration).

          6.2.2   Parent Indemnity. Subject to the provisions of Sections 6.1
                  ----------------
and 6.3, the Parent shall indemnify, save and hold harmless the Shareholders and
the Shareholders' heirs, legal representatives, successors and assigns from and
against all Losses arising from, out of or in any manner connected with or based
on:

          (i)     any breach of any covenant of the Parent or Merger Sub or the
     failure by the Parent or Merger Sub to perform any of its obligations
     contained herein or in the Parent Related Documents;

          (ii)    any inaccuracy in or breach of any representation or warranty
     of the Parent or Merger Sub contained herein or in the Parent Related
     Documents; and

          (iii)   any act, omission, event, condition or circumstance occurring
     or existing at any time after (but not on or before) the Effective Time and
     involving or relating to the assets, properties, businesses or operations
     of the Company; provided, however, that this clause (iii) shall not apply
     to any Losses to the extent that such Losses result from any Shareholder's
     acts or omissions after the Effective Time as an officer, director and/or
     employee of the Parent, the Surviving Corporation and/or any other
     affiliate of the Parent.

The foregoing indemnities shall not limit or otherwise adversely affect the
Parent Indemnified Parties' rights of indemnity for Losses under Section 6.2.1.

     6.3  Limitations.  The aggregate liability of the Shareholders under
          -----------                                                    
Sections 6.2.1(ii) and (iii) shall not exceed  the cash amount equal to the
Total Consideration with the Parent Common Stock being valued at the IPO Price
to the Public for such purpose. The aggregate liability of the Parent under
Section 6.2.2(ii) shall not exceed the cash amount equal to the Total
Consideration with the Parent Common Stock being valued at the IPO Price to the
Public for such purpose.

     6.4  Procedures for Indemnification.
          ------------------------------ 

          6.4.1   Notice. The party (the "Indemnified Party") that may be
                  ------                  -----------------
entitled to indemnity hereunder shall give prompt notice to any party obligated
to give indemnity hereunder (the "Indemnifying 
                                  ------------

                                     -18-
<PAGE>
 
Party") of the assertion of any claim, or the commencement of any suit, action
-----
or proceeding in respect of which indemnity may be sought hereunder. Any failure
on the part of any Indemnified Party to give the notice described in this
Section 6.4.1 shall relieve the Indemnifying Party of its obligations under this
Article 6 only to the extent that such Indemnifying Party has been prejudiced by
the lack of timely and adequate notice (except that the Indemnifying Party shall
not be liable for any expenses incurred by the Indemnified Party during the
period in which the Indemnified Party failed to give such notice). Thereafter,
the Indemnified Party shall deliver to the Indemnifying Party, promptly (and in
any event within 10 days thereof) after the Indemnified Party's receipt thereof,
copies of all notices and documents (including court papers) received by the
Indemnified Party relating to such claim, action, suit or proceeding.

          6.4.2   Legal Defense.  The Parent shall have the obligation to assume
                  -------------                                                 
the defense or settlement of any third-party claim, suit, action or proceeding
in respect of which indemnity may be sought hereunder, provided that (i) the
Shareholders shall at all times have the right, at their option, to participate
fully therein, and (ii) if the Parent does not proceed diligently to defend the
third-party claim, suit, action or proceeding within 10 days after receipt of
notice of such third-party claim, suit, action or proceeding, the Shareholders
shall have the right, but not the obligation, to undertake the defense of any
such third-party claim, suit, action or proceeding.

          6.4.3   Settlement.  The Indemnifying Party shall not be required to
                  ----------                                                  
indemnify the Indemnified Party with respect to any amounts paid in settlement
of any third-party suit, action, proceeding or investigation entered into
without the written consent of the Indemnifying Party; provided, however, that
if the Indemnified Party is a Parent Indemnified Party, such third-party suit,
action, proceeding or investigation may be settled without the consent of the
Indemnifying Party on 10 days' prior written notice to the Indemnifying Party if
such third-party suit, action, proceeding or investigation is then unreasonably
interfering with the business or operations of the Company or the Surviving
Corporation and the settlement is commercially reasonable under the
circumstances; and provided further, that if the Indemnifying Party gives 10
days' prior written notice to the Indemnified Party of a settlement offer which
the Indemnifying Party desires to accept and to pay all Losses with respect
thereto ("Settlement Notice") and the Indemnified Party fails or refuses to
          -----------------                                                
consent to such settlement within 10 days after delivery of the Settlement
Notice to the Indemnified Party, and such settlement otherwise complies with the
provisions of this Section 6.4, the Indemnifying Party shall not be liable for
Losses arising from such third-party suit, action, proceeding or investigation
in excess of the amount proposed in such settlement offer.  Notwithstanding the
foregoing, no Indemnifying Party will consent to the entry of any judgment or
enter into any settlement without the consent of the Indemnified Party, if such
judgment or settlement imposes any obligation or liability upon the Indemnified
Party other than the execution, delivery or approval thereof and customary
releases of claims with respect to the subject matter thereof.

          6.4.4   Cooperation. The parties shall cooperate in defending any such
                  -----------
third-party suit, action, proceeding or investigation, and the defending party
shall have reasonable access to the books and records, and personnel in the
possession or control of the Indemnified Party that are pertinent to the
defense. The Indemnified Party may join the Indemnifying Party in any suit,
action, claim or proceeding brought by a third party, as to which any right of
indemnity created by this Agreement would or might apply, for the purpose of
enforcing any right of the indemnity granted to such Indemnified Party pursuant
to this Agreement.

                                     -19-
<PAGE>
 
     6.5  Subrogation.  Each Indemnifying Party hereby waives for itself,
          -----------                                                    
himself or herself and its, his or her affiliates (as defined in Exhibit 2) any
rights to subrogation against any Indemnified Party or such Indemnified Party's
insurers for Losses arising from any third-party claims for which the
Indemnifying Party is liable or against which the Indemnifying Party
indemnifies any Indemnifying Party and, if necessary, each Indemnifying Party
shall obtain waivers of such subrogation from its, his or her insurers.

                                7.  TERMINATION

     7.1  Grounds for Termination.  This Agreement may be terminated at any time
          -----------------------                                               
prior to the Closing Date:

          7.1.1   Mutual Consent. By the written agreement of the Company and
                  --------------
the Parent; or

          7.1.2   Optional By the Company. By the Company by written notice to
                  -----------------------
the Parent, if the Closing shall have failed to occur by 5:00 p.m. Houston,
Texas time on December 31, 1997, but only if neither the Company nor any
Shareholder has breached this Agreement or has failed to perform any of their
respective obligations under this Agreement;

          7.1.3   Optional By the Parent. By the Parent, by written notice to
                  ----------------------
the Company, if the Closing shall have failed to occur by 5:00 p.m. Houston,
Texas time on December 31, 1997, but only if neither the Parent nor Merger Sub
has breached this Agreement or has failed to perform any of its obligations
under this Agreement;

          7.1.4   Breach By the Parent or Merger Sub. By the Company, by written
                  ----------------------------------
notice to the Parent, if either the Parent or Merger Sub has materially breached
this Agreement or materially failed to perform any of its obligations under this
Agreement; or

          7.1.5   Breach by the Company or any Shareholder.  By the Parent, by
                  ----------------------------------------                    
written notice to the Company, if the Company or any Shareholder has materially
breached this Agreement or has materially failed to perform any of their
respective obligations under this Agreement.

     7.2  Effect of Termination.  If this Agreement is terminated as permitted
          ---------------------                                               
under Section 7.1, such termination shall be without liability of any party to
any other party, except that such termination shall be without prejudice to any
and all remedies the parties may have against each other for breach of this
Agreement.

                               8. MISCELLANEOUS

      8.1 Notice.  Any notice, delivery or communication required or permitted
          ------                                                              
to be given under this Agreement shall be in writing, and shall be mailed,
postage prepaid, or delivered, to the addresses given below, or sent by telecopy
to the telecopy numbers set forth below, as follows:

                                     -20-
<PAGE>
 
     To the Company (prior to the Effective Time) or the Shareholders:

          Yale Incorporated
          9649 Girard Avenue South
          Minneapolis, Minnesota 55431
          Attention: Mr. William Rikkers
          Telecopy: (612) 884-0295

     To the Parent or Merger Sub or the Surviving Corporation:

          Group Maintenance America Corp.
          1800 West Loop South, Suite 1375
          Houston, Texas 77027
          Attn: President
          Telecopy: (713) 626-4766

or other such address as shall be furnished in writing by any such party to the
other parties, and such notice shall be effective and be deemed to have been
given as of the date actually received.

     To the extent any notice provision in any other agreement, instrument or
document required to be executed or executed by the parties in connection with
the transactions contemplated herein contains a notice provision which is
different from the notice provision contained in this Section 8.1 with respect
to matters arising under such other agreement, instrument or document, the
notice provision in such other agreement, instrument or document shall control.

     8.2  Further Documents.  The Shareholders shall, at any time and from time
          -----------------                                                    
to time after the date hereof, upon request by the Parent and without further
consideration, execute and deliver such instruments or other documents and take
such further action as may be reasonably required in order to perfect any other
undertaking made by the Shareholders hereunder.

     8.3  Assignability.  The Shareholders shall not assign this Agreement in
          -------------                                                      
whole or in part without the prior written consent of the Parent, except by the
operation of law.  The Parent may assign its rights under this Agreement, the
Company Related Documents and the Shareholder Related Documents without the
consent of any Shareholder or the Company.  After the Effective Time, the
Surviving Corporation may assign its rights under this Agreement, the Company
Related Documents and the Shareholder Related Documents without the consent of
any Shareholder.

     8.4  Exhibits and Schedules.  The Exhibits and Schedules (and any
          ----------------------                                      
appendices thereto) referred to in this Agreement are and shall be incorporated
herein and made a part hereof.

     8.5  Sections and Articles.  Unless the context otherwise requires, all
          ---------------------                                             
Sections, Articles and Exhibits referred to herein are, respectively, sections
and articles of, and exhibits to, this Agreement and all Schedules referred to
herein are schedules constituting a part of the Disclosure Schedule.

     8.6  Entire Agreement.  This Agreement constitutes the full understanding
          ----------------                                                    
of the parties, a complete allocation of risks between them and a complete and
exclusive statement of the terms and 

                                     -21-
<PAGE>
 
conditions of their agreement relating to the subject matter hereof and
supersedes any and all prior agreements, whether written or oral, that may exist
between the parties with respect thereto. Except as otherwise specifically
provided in this Agreement, no conditions, usage of trade, course of dealing or
performance, understanding or agreement purporting to modify, vary, explain or
supplement the terms or conditions of this Agreement shall be binding unless
hereafter made in writing and signed by the party to be bound, and no
modification shall be effected by the acknowledgment or acceptance of documents
containing terms or conditions at variance with or in addition to those set
forth in this Agreement. No waiver by any party with respect to any breach or
default or of any right or remedy and no course of dealing shall be deemed to
constitute a continuing waiver of any other breach or default or of any other
right or remedy, unless such waiver be expressed in writing signed by the party
to be bound. Failure of a party to exercise any right shall not be deemed a
waiver of such right or rights in the future.

     8.7  Headings.  Headings as to the contents of particular articles and
          --------                                                         
sections are for convenience only and are in no way to be construed as part of
this Agreement or as a limitation of the scope of the particular articles or
sections to which they refer.

     8.8  CONTROLLING LAW.  THE VALIDITY, INTERPRETATION AND PERFORMANCE OF THIS
          ---------------                                                       
AGREEMENT AND ANY DISPUTE CONNECTED HEREWITH SHALL BE GOVERNED AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF TEXAS EXCEPT TO THE EXTENT THE
APPLICABLE CORPORATE LAW MANDATORILY APPLIES WITH RESPECT THERETO.

     8.9  Public Announcements.  After the Effective Time, no Shareholder shall
          --------------------                                                 
make any press release, public announcement, or public confirmation or disclose
any other information regarding this Agreement or the contents hereof.

     8.10 No Third Party Beneficiaries.  Except as set forth in Article 6, no
          ----------------------------                                       
person or entity not a party to this Agreement shall have rights under this
Agreement as a third party beneficiary or otherwise.

     8.11 Amendments and Waivers.  This Agreement may be amended by the Parent,
          ----------------------                                               
Merger Sub and the Company, by action taken by their Boards of Directors to the
extent permitted by applicable law; provided, however, that no such amendment
shall (i) alter or change any provision of this Agreement, the alteration or
change of which must be adopted by the holders of capital stock of the Company
under the certificate or articles of incorporation of the Company or the
Applicable Corporate Law, or (ii) alter or change this Section 8.11, unless each
such alteration or change is adopted by the holders of shares of capital stock
of the Company as may be required by the certificate or articles of
incorporation of the Company or the Applicable Corporate Law.  Prior to the
Effective Time, all amendments to this Agreement must be by an instrument in
writing signed on behalf of the Parent, Merger Sub, the Company and the
Shareholders. After the Effective Time, all amendments to this Agreement must be
by an instrument in writing signed on behalf of the Parent and the Shareholders.
Any term or provision of this Agreement (other than the requirements for
shareholder approvals) may be waived in writing at any time by the party which
is, or whose shareholders are, entitled to the benefits thereof.

     8.12 No Employee Rights.  Nothing herein expressed or implied shall confer
          ------------------                                                   
upon any employee of the Company, any other employee or legal representatives or
beneficiaries of any thereof any rights or remedies, including any right to
employment or continued employment for any specified period, of any 

                                     -22-
<PAGE>
 
nature or kind whatsoever under or by reason of this Agreement, or shall cause
the employment status of any employee to be other than terminable at will.

     8.13 Non-Recourse.  No recourse for the payment of any amounts due
          ------------                                                 
hereunder or for any claim based on this Agreement or the transactions
contemplated hereby or otherwise in respect thereof, and no recourse under or
upon any obligation, covenant or agreement of the Parent in this Agreement shall
be had against any incorporator, organizer, promoter, shareholder, officer,
director, employee or representative as such (other than the Shareholders as set
forth herein), past, present or future, of the Parent or of any successor
corporation, whether by virtue of any constitution, statute or rule of law, or
by enforcement of any assessment or penalty or otherwise; it being expressly
understood that all such liability is hereby expressly waived and released as a
condition of, and as a consideration for, the execution of this Agreement.

     8.14 When Effective.  This Agreement shall become effective only upon the
          --------------                                                      
execution and delivery of one or more counterparts of this Agreement by each of
the Parent, Merger Sub, the Company and the Shareholders.

     8.15 Takeover Statutes.  If any "fair price," "moratorium," "control share
          -----------------                                                    
acquisition" or other form of anti-takeover statute or regulation shall become
applicable to the transactions contemplated hereby, the Parent and the Company
and their respective members of their Boards of Directors shall grant such
approvals and take such actions as are necessary so that the transactions
contemplated by this Agreement may be consummated as promptly as practicable on
the terms contemplated herein and otherwise act to eliminate or minimize the
effects of such statute or regulation on the transactions contemplated herein.

     8.16 Number and Gender of Words.  Whenever herein the singular number is
          --------------------------                                         
used, the same shall include the plural where appropriate and words of any
gender shall include each other gender where appropriate.

     8.17 Invalid Provisions.  If any provision of this Agreement is held to be
          ------------------                                                   
illegal, invalid, or unenforceable under present or future laws, such provisions
shall be fully severable as if such invalid or unenforceable provisions had
never comprised a part of the Agreement; and the remaining provisions of the
Agreement shall remain in full force and effect and shall not be affected by the
illegal, invalid or unenforceable provision or by its severance from this
Agreement.  Furthermore, in lieu of such illegal, invalid or unenforceable
provision, there shall be automatically as a part of this Agreement, a provision
as similar in terms to such illegal, invalid or unenforceable provision as may
be possible and be legal, valid and enforceable.

     8.18 Multiple Counterparts.  This Agreement may be executed in a number of
          ---------------------                                                
identical counterparts.  If so executed, each of such counterparts is to be
deemed an original for all purposes and all such counterparts shall,
collectively, constitute one agreement, but, in making proof of this Agreement,
it shall not be necessary to produce or account for more than one such
counterpart.

     8.19 No Rule of Construction.  All of the parties hereto have been
          -----------------------                                      
represented by counsel in the negotiations and preparation of this Agreement;
therefore, this Agreement will be deemed to be drafted by each of the parties
hereto, and no rule of construction will be invoked respecting the authorship of
this Agreement.

                                     -23-
<PAGE>
 
     8.20 Expenses.  Each of the parties shall bear all of their own expenses in
          --------                                                              
connection with the negotiation and closing of this Agreement and the
transactions contemplated hereby; provided that the Company shall pay the costs
of any broker, legal counsel, accountants (for the audit of the Company through
the prior fiscal year but not for any stub-period audits) or other advisors
engaged by the Shareholders (to the extent, and only to the extent, that any
such payment will not jeopardize the qualification of the Merger as a
reorganization within the meaning of Section 368(a) of the Code); and provided
further that all fees, costs and expenses incurred or payable by the Company in
connection with the negotiation and closing of this Agreement and the
transactions contemplated hereby (including the accounting and audit fees of the
Accountants), and not yet paid, shall be included in current liabilities for
purposes of determining Working Capital.  In the event this Agreement is
terminated due to the failure of the Parent to complete the IPO, the Parent
shall reimburse the Company for the fees paid by the Company to Accountants for
the audit of the Company.

     IN WITNESS WHEREOF, this Agreement has been duly executed and delivered on
the date first hereinabove written.

                              PARENT:

                              GROUP MAINTENANCE AMERICA CORP.


                              __________________________________________________
                                    J.  Patrick Millinor, Jr., President


                              MERGER SUB:

                              YALE ACQUISITION CORP.

                              By:_______________________________________________
                                              President

                              SHAREHOLDERS:


 
                              __________________________________________________
                                    William Rikkers


                              __________________________________________________
                                    Ed Olson


                              
                              __________________________________________________
                                    John Deblon

                                     -24-
<PAGE>
 
                              COMPANY:

                              YALE INCORPORATED


                              By:_______________________________________________
                              Name: William Rikkers
                              Title:Chairman

                                     -25-