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                                                                     EXHIBIT 4.3

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                      BUILDING ONE SERVICES CORPORATION,
                                  as Issuer,


                     C.R. HIPP CONSTRUCTION COMPANY, INC.,
                        DEL-AIR SERVICE COMPANY, INC.,
                            MH TECHNOLOGIES, INC.,
                            S.L. PAGE CORPORATION,
                           TRI-STATE ELECTRIC, INC.,
                               TRI-STATE, INC.,
                       WALTER C. DAVIS & SON, INC., and

                      the other GUARANTORS named herein,

                                 as Guarantors

                                      AND

                      IBJ WHITEHALL BANK & TRUST COMPANY,

                                  as Trustee

                       _________________________________

                            SUPPLEMENTAL INDENTURE

                         Dated as of  January 31, 2000

                       _________________________________

                                  Relating to
                              up to $400,000,000
                       _________________________________

                  10 1/2% Senior Subordinated Notes due 2009


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                            SUPPLEMENTAL INDENTURE

     This supplemental Indenture (the "Supplemental Indenture") dated as of
January 31, 2000, among C.R. Hipp Construction Company, Inc., Del-Air Service
Company, Inc., MH Technologies, Inc., S.L. Page Corporation, Tri-State Electric,
Inc., Tri-State, Inc. and Walter C. Davis & Son, Inc. (the "New Guarantors"),
companies acquired by BUILDING ONE SERVICES CORPORATION, a Delaware corporation
(the "Company") of wholly owned subsidiaries thereof, since the date of the
Indenture (defined below), the existing subsidiary guarantors listed as
signatories hereto (the "Existing Guarantors") and IBJ Whitehall Bank & Trust
Company, a New York banking corporation, as trustee under the Indenture referred
to below (the "Trustee").


                             W I T N E S S E T H:

     WHEREAS, the Company and the Existing Guarantors have heretofore executed
and delivered to the Trustee an indenture (the "Indenture") dated as of April
30, 1999, providing for the issuance of an aggregate principal amount of up to
$400,000,000 of 10 1/2% Senior Subordinated Notes due 2009 (the "Securities");

     WHEREAS, Section 4.18 of the Indenture provides that under certain
circumstances the Company is required to cause the newly acquired subsidiaries
to execute and deliver to the Trustee a supplemental indenture pursuant to which
such subsidiaries shall unconditionally guarantee all of the Company's
obligations under the Securities on the terms and conditions set forth herein;
and

     WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee, the
Company and the Existing Guarantors are authorized to execute and deliver this
Supplemental Indenture;

     NOW THEREFORE, in consideration of the foregoing and for other good and
valuable consideration, the receipt of which is hereby acknowledged, the New
Guarantors, the Company and the Existing Guarantors mutually covenant and agree
for the equal and ratable benefit of the holders of the Securities as follows:

     1. AGREEMENT TO GUARANTEE.  The New Guarantors hereby agree, jointly and
severally with all of the Existing Guarantors, to unconditionally guarantee the
Company's obligations under the Securities on the terms set forth in the
Indenture.

     2. RATIFICATION OF INDENTURE; SUPPLEMENTAL INDENTURE PART OF INDENTURE.
Except as expressly amended hereby, the Indenture is in all respects ratified
and confirmed and all of the terms, conditions and provisions thereof shall
remain in full force and effect.  This Supplemental Indenture shall form a part
of the Indenture for all purposes and every holder of Securities heretofore or
hereafter authenticated and delivered shall be bound hereby.

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

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     4. TRUSTEE MAKES NO REPRESENTATION.  The recitals contained herein shall be
taken as the statements of the Company and the Trustee assumes no responsibility
for their correctness.  The Trustee makes no representation as to the validity
or sufficiency of this Supplemental Indenture.

     5. COUNTERPARTS.  The parties may sign any number of copies of this
Supplemental Indenture.  Each signed copy shall be an original, but all of them
together represent the same agreement.

     6. EFFECT OF HEADINGS.  The Section headings herein are for convenience
only and shall not effect the construction thereof.

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


                              C.R. HIPP CONSTRUCTION COMPANY, INC.,
                              DEL-AIR SERVICE COMPANY, INC.,
                              MH TECHNOLOGIES, INC.,
                              S.L. PAGE CORPORATION,
                              TRI-STATE ELECTRIC, INC.,
                              TRI-STATE, INC.,
                              WALTER C. DAVIS & SON, INC.
                                   by:

                                   /s/ F. T. BECK
                                   _____________________________
                                   Name:  F. Traynor Beck
                                   Title: Vice President & Assistant Secretary


                              BUILDING ONE SERVICES CORPORATION
                                   by:

                                   /s/ F. T. BECK
                                   _____________________________
                                   Name:  F. Traynor Beck
                                   Title: Executive Vice President


                              ADVENT ELECTRIC CO., INC.
                              AMERICAN AIR CO., INC.
                              BARNES IVEY MECHANICAL COMPANY,
                                L.L.C.
                              BELTLINE MECHANICAL SERVICES, INC.
                              BOXBERGER, INC.
                              BRAZOSPORT MANAGEMENT, INC.
                              BUILDING ONE MECHANICAL SERVICES,
                                INC.
                              BUILDING ONE SERVICE SOLUTIONS, INC.
                              BUYR, INC.

                                      -2-
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                              CHAMBERS ELECTRONIC
                                COMMUNICATIONS, INC.
                              CONSOLIDATED ELECTRICAL GROUP, INC.
                              CRAMAR ELECTRIC, INC.
                              CREST INTERNATIONAL, LLC
                              D/FW MECHANICAL SERVICES, INC.
                              ELECTRICAL DESIGN & CONSTRUCTION,
                                INC.
                              ENGINEERING DESIGN GROUP, INC.
                              FLOR-SHIN, INC.
                              FRED CLARK ELECTRICAL CONTRACTORS,
                                INC.
                              G.S. FINANCIAL, INC.
                              G.S. GROUP, INC.
                              GAMEWELL MECHANICAL, INC.
                              GARFIELD-INDECON ELECTRICAL
                                SERVICES, INC.
                              G.S.I. OF CALIFORNIA, INC.
                              GULF STATES, INC.
                              HUNT ELECTRIC, INC.
                              IVEY MECHANICAL COMPANY, INC.
                              IVEY MECHANICAL SERVICES, L.L.C.
                              LEXINGTON/IVEY MECHANICAL COMPANY,
                                L.L.C.
                              MCINTOSH MECHANICAL, INC.
                              NATIONAL NETWORK SERVICES, INC.
                              OIL CAPITAL ELECTRIC, INC.
                              OMNI MECHANICAL COMPANY
                              OMNI MECHANICAL SERVICES
                              PERIMETER MAINTENANCE CORPORATION
                              POTTER ELECTRIC CO., INC.
                              PRO WIRE SECURITY SYSTEMS, INC.
                              REGENCY ELECTRIC COMPANY ATLANTA
                                OFFICE
                              REGENCY ELECTRIC COMPANY
                                CHARLOTTE OFFICE, INC.
                              REGENCY ELECTRIC COMPANY JACKSONVILLE OFFICE, INC.
                              REGENCY ELECTRIC COMPANY MEMPHIS
                                OFFICE, INC.
                              REGENCY ELECTRIC COMPANY ORLANDO
                                OFFICE, INC.
                              REGENCY ELECTRIC COMPANY PROJECTS
                                GROUP, INC.
                              REGENCY ELECTRIC COMPANY SOUTH
                                FLORIDA, INC.
                              REGENCY ELECTRIC COMPANY, INC.
                              RIVIERA ELECTRIC CONSTRUCTION CO.

                                      -3-
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                              RIVIERA ELECTRIC OF CALIFORNIA, INC.
                              ROBINSON MECHANICAL COMPANY
                              SANDERS BROS., INC.
                              SKC ELECTRIC, INC.
                              SKCE, INC.
                              SPANN BUILDING MAINTENANCE
                                COMPANY
                              SPANN MANAGEMENT GROUP, INC.
                              TAYLOR ELECTRIC, INC.
                              TESS HOLDINGS, INC.
                              TESTRONICS, INC.
                              THE LEWIS COMPANIES, INC.
                              TOWN & COUNTRY ELECTRIC, INC.
                              TRI-CITY ELECTRICAL CONTRACTORS, INC.
                              TRI-M HOLDING CORP.
                              TRI-M CORPORATION
                              TRI-M ELECTRICAL CONSTRUCTION CORP.
                              TRI-M BUILDING AUTOMATION SYSTEMS
                                CORP.
                              TRI-M INFORMATION SYSTEMS CORP.
                              TRI-M INTEGRATED SYSTEMS SOLUTIONS
                                CORP.
                              WALKER ENGINEERING, INC.
                              WARREN ELECTRICAL CONSTRUCTION
                                CORP.
                              WATSON ELECTRICAL CONSTRUCTION CO.
                              WILSON ELECTRIC COMPANY, INC.
                              ELECTRICAL CONTRACTING, INC.
                              MOUNTAIN VIEW ELECTRIC, INC.,
                              B & R ELECTRIC, INC.
                              ATLANTIC ELECTRIC, INC.
                              K & A MECHANICAL, INC.
                              SULLIVAN ELECTRIC, INC.
                                   by


                                   /s/ F. T. BECK
                                   _____________________________
                                   Name:  F. Traynor Beck
                                   Title: Vice President & Assistant Secretary

                              IBJ WHITEHALL BANK & TRUST COMPANY,
                                as Trustee

                                   by

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                                   /s/ TERENCE RAWLINS
                                   __________________________________
                                   Name:  Terence Rawlins
                                   Title: Vice President

                                      -5-