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8/22/14 – REV#1
UniSpec II
102612
SECTION 07721 (07 7213) - MANUFACTURED CURBS
PART 1 - GENERAL
1.1
1
SUMMARY
A.
Section Includes:
1.
Owner furnished manufactured structural and non-structural metal roof curbs and adapter curbs for
installation by Contractor.
2.
Manufactured non-structural metal roof curbs furnished and installed by Contractor.
B.
Related Requirements:
1.
Section 01640 - Owner Furnished Products: General procedures related to Owner furnished products.
2.
Section 01645 – Owner Furnished Products Sources: Manufacturers, suppliers, and vendor contacts and
product names and numbers related to Owner furnished products.
3.
Section 05120 - Structural Steel: Roof opening frames and headers.
4.
Section 05210 - Steel Joists: Joists supporting roof curbs.
5.
Section 07500 - Membrane Roofing: Board insulation for roof curbs.
6.
Section 07620 - Sheet Metal Flashing and Trim: Sheet metal flashing installed in conjunction with roof
penetration curbs.
7.
Section 07722 - Roof Hatches.
8.
Section 08631 - Metal Framed Skylights.
9.
Section 15600 - Refrigeration Systems.
10.
Section 15700 - Heating, Ventilating and Air Conditioning Equipment.
11.
Section 15800 – Air Distribution: Grease laden exhaust ductwork duct exhaust fan curbs. Grease duct
curbs are included as part of the Grease Duct System by Metal Fab.
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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 - Steel Sheet, Aluminum Coated by the Hot-Dip Process.
2.
ASTM A 653 - Steel Sheet, Zinc-Coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the
Hot-Dip Process.
3.
ASTM A 792 - Steel Sheet, 55% 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 Type II- 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 rectangular 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
A.
1.5
QUALITY ASSURANCE
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 Owner.
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, Type C - skylights, Type D - satellite dish, Type E - expansion joints, 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
1
1
OWNER FURNISHED PRODUCTS
A.
Under provisions of Section 01640, All products specified in this section will be owner's supplier will furnished
structural roof curbs, adapter curbs 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.
B.
Owners Supplier for roof curbs and adapter curbs will be as follows:
1.
Reference corresponding paragraph in Section 01645
2.2
MANUFACTURERS
A.
Structural Roof Curbs: Owner’s supplier for structural roof curbs and adapter curbs will be as follows
1.
Reference corresponding paragraph in Section 01645.
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.
Curbs Plus, Rossville, GA. Contact Marc Brower (888) 639-2872..
2.3
A.
MATERIALS
Sheet Steel: One of the following:
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 07500.
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.
F.
Finish Paint:
1.
Primer: One coat Speedhide Super Tech Dry-Fog Epoxy Ester #6-157 by PPG.
2.
Finish: One coat Speedhide Super Tech Alkyd Dry-Fog Enamel, Eggshell # 6-151 by PPG.
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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: Unless otherwise required by local codes, minimum curb height from top of bar joist to top of curb
shall be as specified below but in no case less than 8 inches from top of roof membrane to top of curb:
1.
All Rooftop Unit Curbs Unless Otherwise Shown or Specified: 18 inches.
2.
Hybrid House Curbs: 11 4 inches.
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 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 3/8 inch per foot only if the unit outdoor air intake (return air end) is oriented toward
the high side of the roof pitch.
2.
Air Handling Unit (AHU) Curbs: Provide tapered rail curbs. Construct curb for AHU to be level (verify
roof slope).
3.
Double Cross-Sloped and Side-Sloped Curbs: Provide tapered rail curbs for level mounting of RTUs when
located in a cross-sloped or side-sloped section of roof as shown on the structural roof plan. Curbs
fabricated for cross-sloped or side-sloped installation shall be clearly marked by the manufacturer to
indicate for special application.
G.
Skylight Curbs Safety Screen:
1.
Internal Support Frame for Safety Screen: 14 gauge, 3/4"x3/4" maximum galvanized steel support angle to
interior perimeter walls of curb, recessed from top flange 3/4" minimum. Internal support frame for safety
screen to be welded to curb at 12" on center with minimum 1" welds.
2.
Safety Screen: Shop fabricated 3/16 inch cold rolled galvanized steel rods welded in 6 inch by 6 inch grid
pattern. Weld screen to internal support frame at each grid point. Do not mount safety screen on top of
curb nor attached to curb wall. When venting skylights are used, allow room at top inside face of curb for
smoke vent installation. Internal support frame and screen shall have been tested to withstand impact of
245 pound lead weight, 10-3/4 inch diameter, dropped from height of 3 feet and support concentrated load
of 600 pounds after impact.
H.
Shop Painting: Shop finish interior surfaces of curbs including safety screen and hardware kit of items that will be
exposed to the public after installation. Use PPG dry fog coating as specified; color to match Sherwin-Williams
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Shrewsbury, MO – 3061-00
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#SW6385 “Dover White”.
I.
2.5
Hybrid House Curb: Provide tapered rail curbs. Construct curb for hybrid house to be level (verify roof slope).
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.
B.
Grease Duct Exhaust Fan Curbs:
1.
Grease duct curbs shall be manufactured as a part of the 3G Grease Duct System by Metal-Fab, Wichita,
KS, as specified in Section 15800. Contact: CVP Customer Service, (800) 835-2830.
2.
Coordinate delivery of grease duct curbs with mechanical contractor and grease duct curb supplier such that
grease duct curbs are installed concurrent with curbs specified herein.
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2.6
A.
2.7
A.
WIND/SEISMIC RESTRAINT BRACKETS (OWNER FURNISHED - CONTRACTOR INSTALLED)
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.
SUBSTITUTIONS
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.
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 HVAC equipment in accordance with manufacturer’s
recommendations.
3.2
A.
3.3
A.
INTERFACE WITH OTHER WORK
Coordinate project requirements for custom adapting and connecting to roof curbs with manufacturers and suppliers
of curb mounted items and equipment.
ROOF CURB SCHEDULE
Structural Curbs: Owner furnished structural curbs and adapter curbs will be provided for the following items:
1.
HVAC roof top units (RTU).
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Shrewsbury, MO – 3061-00
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2.
3.
4.
5.
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B.
Air handling units (AHU).
Hybrid House.
Duct openings between bottom of elevated AHU on structural frame and roof.
Skylights.
Non-Structural Curbs: Provide Owner Furnished non-structural roof curbs will be furnished for the following
items:
1.
Exhaust fans unless shown otherwise shown to be provided by others.
END OF SECTION
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Shrewsbury, MO – 3061-00
08/19/13