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UniSpec II - Store Planning 103114
SECTION 07721 - MANUFACTURED CURBS
PART 1 - GENERAL
1.1 SUMMARY
A. Section Includes:
1. Manufactured structural metal roof curbs furnished by Owner for installation by Contractor.
2. Manufactured non-structural metal roof curbs furnished and installed by Contractor.
3. Coordination with manufacturers and suppliers of roof mounted items and equipment.
B. Related Sections:
1. Section 05120 - Structural Steel: Roof opening frames and headers.
2. Section 05210 - Steel Joists: Joists supporting roof curbs.
3. Section 07511 - Built-up Asphalt Roofing: Board insulation for roof curbs.
4. Section 07530 - Elastomeric Membrane Roofing: Board insulation for roof curbs.
5. Section 07550 - Modified Bituminous Membrane Roofing: Board insulation for roof curbs.
6. Section 07620 - Sheet Metal Flashing Trim: Sheet metal flashing installed in conjunction with roof
penetration curbs.
7. Section 15600 – Refrigeration Systems.
8. Section 15700 - Heating, Ventilating and Air Conditioning Equipment.
9. Section 15800 – Air Distribution: Grease duct exhaust fan curbs supplied by grease duct manufacturer.
1.2 REFERENCES
A. The publications listed below form a part of this specification to the extent referenced. Publications are referenced
within the text by the basic designation only.
B. American Welding Society (AWS): AWS D1.1 - Structural Welding Code.
C. ASTM International (ASTM):
1. ASTM A 463 - Specification for Steel Sheet, Cold Rolled, Aluminum Coated Type 1 and Type 2.
2. ASTM A 653 - Specification for Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated
(Galvannealed) by the Hot-Dip Process.
3. ASTM A 792 - Specification for Steel Sheet, Fifty-Five Percent Aluminum-Zinc Alloy-Coated by the Hot-
Dip Process.
D. Steel Structures Painting Council (SSPC):
1. SSPC-Paint 20 Zinc Rich Coating Type I - Inorganic and Organic.
1.3 DEFINITIONS
A. Structural Roof Curb: Manufactured square or rectangular roof curb, bearing on structural steel joists or headers,
designed to support equipment dead load and roof dead and live loads.
B. Non-Structural Roof Curb:
1. Deck Penetrations - 10 Inches by 10 Inches or Less: Manufactured square or rectangular roof curb,
bearing on top of metal roof deck, designed to receive sheet metal flashing skirt, not used for support of
equipment.
2. Deck Penetrations - Greater Than 10 Inches by 10 Inches: Manufactured square or rectanular roof curb
bearing on structural steel angle frame, designed to support equipment dead load. Roof dead and live load
supported by structural angle frame.
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1.4 QUALITY ASSURANCE
A. Qualifications for Welding Work: Qualify field welding operators in accordance with AWS Standard
Qualification Procedures. Provide certification that field welders have satisfactorily passed AWS qualification
tests within previous 12 months.
1. If recertification of welders is required, provide without additional cost to Wal-Mart.
B. Structural Curbs: Provide manufactured metal roof curbs designed by a licensed engineer. Meet or exceed Live
Loads and Dead Loads as specified in this Section and as indicated on Drawings. Coordinate curb dimensions
with shop drawings of equipment to be supported.
1.5 DELIVERY, STORAGE AND HANDLING
A. Transport, handle, store, and protect products in compliance with the requirements of Section 01600 and
manufacturer's recommendations. Receive Owner Furnished products in compliance with the requirements of
Section 01640.
B. Ship curbs to site palletized and banded.
C. Curb manufacturer shall furnish Curb Schedule to Contractor identifying curb "Type" and roof penetration for
which curb is to be used. Curb Schedule shall identify identical curbs as single "Type" (i.e. Type A - 10 ton
RTU's, Type B - 5 ton RTU's, etc.). Identify each curb with "Type" designation painted in 1 inch high letters on
outside face of curb.
D. Stack curbs at site to prevent twisting, bending or permanent deformation.
PART 2 - PRODUCTS
2.1 OWNER FURNISHED PRODUCTS
A. Under provisions of Section 01640, Owner's supplier will furnish structural roof curbs (including adaptor curbs if
shown) and associated wind seismic restraint brackets (when required) for installation by the Contractor.
1. Non-structural roof curbs shall be Contractor furnished and installed.
2. Descriptions and specifications of Owner furnished items and equipment hereinafter are included as
information to the Contractor only and not to be considered as Contractor requirements unless otherwise
stated.
2.2 MANUFACTURERS
A. Structural Roof Curbs: Wal-Mart supplier for structural roof curbs and adaptor curbs will be as follows:
1. AES Industries, Tallassee, AL, Contact: Chad Burt (800) 786-0402.
B. Non-Structural Roof Curbs: Subject to compliance with project requirements, provide prefabricated metal roof
curbs manufactured by one of the following:
1. AES Industries, Tallassee, AL, Contact: Chad Burt (800) 786-0402.
2.3 MATERIALS
A. Sheet Steel: One of the following at Contractor's option:
1. Galvanized Steel Sheet: ASTM A 653, SS (Structural Steel) Classification, Grade 33, G60 hot-dip zinc
coating.
2. Aluminum-Coated Steel Sheet: ASTM A 463, SS (Structural Steel) Classification, Grade 33, Type 2, T2
100 aluminum coating.
3. Aluminum Zinc Alloy-Coated Steel Sheet (GAVALUME): ASTM A 792, AZ55 aluminum zinc alloy
coating.
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B. Board Insulation: Specified in Section 07511, 07530, or 07550 as applicable.
C. Wood Nailers: CCA Pressure Treated Lumber Type C, "Standard" grade lumber of any species.
D. Zinc-Rich Primer: SSPC-Paint 20 Type II.
E. Deck Support Clip: Galvanized steel sheet, gauge as shown.
2.4 STRUCTURAL ROOF CURBS (OWNER FURNISHED - CONTRACTOR INSTALLED)
A. Fabrication, General: Coated 14 gauge steel sheet curb sections, corners fully mitered and welded; 2 inch by 4
inch (nominal dimension) pressure treated continuous wood nailers mechanically fastened with corrosion resistant
fasteners at 12 inches on center to exterior face of curb. Shop prime welded connections with zinc-rich paint
complying with SSPC-Paint 20.
B. Adapter Curbs: Curbs shall be fully welded and insulated. Blank off open areas not used for supply and return air
to prevent air mixing. Construct adapter curbs with the minimum height required to achieve proper airflow.
Verify curb type, size, and unit prior to fabrication.
C. Curb Height: Comply with local code requirements for minimum curb height, but in no case shall curb height be
less than 14 inches, as measured from top of bar joist to top of curb, nor shall curb height be less than 8 inches as
measured from top of roof membrane to top of curb.
D. Reinforce curb sections as required for design loads indicated on Drawings.
E. Welding: AWS D1.1.
F. Mechanical unit curbs: Label curbs with “FRONT” designating the curb orientation to the front of store prior to
shipment. Mechanical unit curbs will be provided as follows as applicable:
1. Roof Top Unit (RTU) Curbs: Provide continuous height rail curbs. It is acceptable for units to follow roof
slopes not exceeding 1/4 inch per foot, unless noted otherwise on structural drawings.
2. Make-Up Air Unit (MAU) Curbs: Provide tapered rail curbs. Construct curb for MAU to be level (verify
roof slope).
3. Air Handling Unit (AHU) Curbs: Provide tapered rail curbs. Construct curb for AHU to be level (verify
roof slope).
4. Evaporative Cooler (EC) Unit Curbs: Provide tapered rail curbs. Construct curb for EC to be level (verify
roof slope).
5. Double roof slope curbs: Provide tapered rail curbs for level mounting of RTUs when located in a double
sloped section of roof as shown on the structural roof plan. Curbs fabricated for double sloped installation
shall be clearly marked by the manufacturer to indicate for special application.
G. Refrigeration Line Curbs at Condenser/Compressor Rack (Weatherpac) on Roof (15 inches high): Provide
continuous height rail curbs. It is acceptable to follow roof slopes not exceeding 1/4 inch per foot, unless noted
otherwise on Structural drawings. Provide curb for required opening for refrigerant piping and electrical conduit
at elevated condenser/compressor rack mounted on a structural frame.
2.5 NON-STRUCTURAL ROOF CURBS (CONTRACTOR FURNISHED AND INSTALLED)
A. Coated 18 gauge steel sheet curb sections, corners fully mitered and welded; 2 inch by 4 inch (nominal dimension)
pressure treated continuous wood nailers mechanically fastened at 12 inches on center to exterior face of curb.
Shop prime welded connections with zinc-rich paint complying with SSPC-Paint 20. Profile and dimensions shall
be as shown.
1. Web Height: Comply with local code requirements for minimum curb height, but in no case shall curb
height be less than 18 inches for deck penetrations greater than 10 inches by 10 inches and not less than 14
inches for deck penetrations 10 inches by 10 inches or less as measured from top of steel roof deck to top
of curb, nor shall curb height be less than 8 inches as measured from top of roof membrane to top of curb.
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2.6 WIND/SEISMIC RESTRAINT BRACKETS
A. When noted on the Mechanical Rooftop Unit or Air Handling Unit Schedules, or Refrigeration Drawings, install
wind and seismic restraint brackets furnished by Owner with curbs for anchorage of rooftop equipment to curbs.
2.7 SUBSTITUTIONS
A. Comply with the requirements of Section 01600.
PART 3 - EXECUTION
3.1 INSTALLATION
A. Install curbs in accordance with manufacturer's instructions and as indicated on Drawings. Coordinate installation
with roof membrane installation requirements specified under other Sections.
B. Roof Curbs Bearing on Steel Angles, Joists, and Headers:
1. Set units in place and secure base to roof structure by welding to top chord of structural member or as
otherwise indicated on Drawings.
2. Secure metal deck to perimeter of curb as indicated on Drawings.
C. Roof Curbs Bearing on Roof Deck:
1. Set units in place and secure base to steel roof deck by self-tapping screw fasteners spaced at a maximum
of 12 inches on center, staggered.
D. Install wind/seismic restraint brackets prior to installation of rooftop equipment in accordance with manufacturer’s
recommendations.
3.2 COORDINATION
A. Coordinate project requirements for custom adapting and connecting to roof curbs with manufacturers and
suppliers of curb mounted items and equipment.
3.3 ROOF CURB SCHEDULE
A. Structural Curbs: Owner furnished structural curbs and adaptors (if applicable) will be supplied for the following
items:
1. Refrigeration lines penetrating roof.
B. Non-Structural Curbs: Provide non-structural roof curbs for the following items:
1. Exhaust fans, unless otherwise shown to be provided by others.
2. Multiple vent pipe penetrations.
END OF SECTION