GAF SBS Membrane Installation Guidelines

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GAF SBS Membrane Installation Guidelines

Notice to the Reader:

The instructions provided below are reprinted from the manufacturer's own materials which were submitted to the RoofStar Guarantee Program for inclusion in this Manual. The reader is urged to check these against current publications issued by the manufacturer, to ensure accuracy.

Manufacturer: GAF

Contact Address: See Membership List in Section 1.

Product Group: SBS MODIFIED BITUMINOUS MEMBRANES

Country of Origin: U.S.A.

Country of Manufacture: U.S.A.

Year First Installed
B.C.: 2002
Canada: 2002

1 Description

GAF’s SBS membranes consist of a polyester mat impregnated on both sides with an SBS modified bitumen compound. The non-woven polyester fabric and glass mat used in GAF’s membranes provides a highly elastic body with excellent tensile strength. The high percentage of plasticizing resins in the bitumen compound ensures heat resistance, low temperature flexibility, aging endurance, and workability.

The GAF membranes are fully adhered with hot asphalt; modified bitumen adhesives or heat welded using a propane torch (Ruberoid® SBS Heat-Weld™ membranes only) to prepared surfaces.

1.1 GENERAL

The roofing assembly/material information published in the RCABC Roofing Practices Manual does NOT represent a complete set of the manufacturer’s published data, nor does it represent a detailed specification. The preparation of a detailed specification is the responsibility of the design authority.

SYSTEM DESCRIPTION

  1. Mop applied roofing membrane consisting of a base sheet and cap sheet, separately applied in full, uniform moppings of hot steep roofing asphalt; apply to any prepared roof substrate or roofing insulation suitable for hot applied roofing asphalt, or to a mechanically attached base sheet.
  2. Cold applied roofing membrane consisting of a base sheet and a cap sheet, separately applied in modified bitumen adhesives; apply to any prepared roof substrate or roofing insulation suitable for modified bitumen adhesives, or to a mechanically attached base sheet.
  3. Torch applied roofing membrane consisting of a base sheet and a cap sheet, separately applied using a proprietary propane torch. Base sheet to flame sensitive substrates are moped applied or mechanically fastened to the prepared substrate or insulation.
  4. Range of application: new construction or reproofing; flat to vertical (consult GAF for specific slope requirements).


DELIVERY, STORAGE, AND HANDLING

  1. Store GAF roofing membranes in a dry place and stacked on end to prevent damage to the selvage edge.
  2. Store rolls on a pallet, securely covered to prevent contact with moisture.
  3. When ambient temperatures are below 0°C (32°F): keep rolls in a heated area; install quickly without allowing to become cold; do not drop rolls when cold.


SITE CONDITIONS

  1. Slope limitations:
    • Minimum recommended slope: 1:50 (1/4" in 12")
    • Mechanical fastening required over: 1:16 (3/4" in 12")
    • Consult GAF for slopes over: 1:4 ( 3" in 12")
  2. Application temperature:
    • Minimum ambient temperature: +4°C (+40°F)
    • Maximum ambient temperature: +38°C (+100°F)
  3. Chemical incompatibilities: generally those that affect roofing asphalt


STANDARDS AND APPROVALS (consult GAF for specific membranes or assemblies)

  1. Underwriters Laboratories: Class A, B and C Flame Resistance, “Roofing Materials and Systems Directory”, 2001 Edition.
  2. Factory Mutual: Class 1 and Class I-90 (consult Factory Mutual Research Approval Guide for additional assemblies and uplift ratings)
  3. Canadian General Standards Board: CGSB 37-GB-56M
  4. Other: Metro-Dade, SWL, SBCCI, CIBC, CABO
  5. Underwriters Laboratories of Canada – Standard CAN / ULC-S107


MANUFACTURER’S SERVICES

  1. Local GAF Commercial Specialists
  2. Specifications and drawings available from application and specification manual
  3. Seminars: Conducted as scheduled or upon request.
  4. Contractor Services Department available for technical questions and documentation.

1.2 MATERIALS

NOTE: Regardless of the materials listed below or anywhere else in these manufacturer's guidelines, only materials accepted for use in the RoofStar Guarantee Program, or accessories associated with those materials, may be used to qualify for a RoofStar Guarantee. To see a list of the manufacturer's products accepted for use in the RoofStar Guarantee Program, click on the link above.

1.3 EXECUTION

PREPARATION

  1. Ensure surfaces are clean, smooth, dry, and free of depressions or sharp projections.
  2. Ensure that roof projections are firmly affixed and cant strips, reglets, and nailing strips are in place; CANT STRIPS ARE REQUIRED where two surfaces meet at a 90° angle.
  3. The design and construction of roof decks and proper drainage is the responsibility of the architect / specifier.


PRIMER

  1. Prime all concrete, masonry, and metal surfaces to be directly bonded with bituminous membranes.


INSULATION

  1. Mechanically fasten insulation over nailable decks and steel decks in accordance with RoofStar Guarantee Standards.
  2. Embed insulation in a full, uniform mopping of hot steep roofing asphalt at a rate of 1.5 kg / m2 (30 lb / 100 ft2) over structural concrete decks.
  3. Install 11 mm (1/2") asphalt impregnated fiberboard or perlite as insulation overlay where required by RGC Guarantee Standards.
  4. Install wood nailers at the perimeter of non-nailable decks and on slopes of 1:16 (3/4" in 12") or greater.


BASE SHEET (where required)

  1. Start at the low point of the roof and perpendicular to the slope.
  2. Mechanically fasten base sheet to the deck in accordance with GAF application and specification requirements.
  3. Asphalt adhered: embed base sheet to suitable substrate in a full, uniform moping of hot steep roofing asphalt at a rate of 1.2 kg / m2 (25 lb per 100 ft2).


PLY SHEETS

  1. Start at the low point of the roof and perpendicular to the slope.
  2. Unroll 1.2 m to 2.0 m (4’ to 6’) and align membrane.
  3. Asphalt adhered: embed ply sheet(s) to suitable substrate in a full, uniform mopping of hot steep roofing asphalt at a rate of 1.2 kg / m2 (25 lb per 100 ft2).
  4. Adhesive adhered: embed membrane to suitable substrate in a full, uniform layer of modified bitumen adhesive applied at a rate of 0.8 L / m2 (1.5 gal per 100 ft2).
  5. Torch adhered (SBS Heat-Weld membranes only): torch apply to suitable substrate with propane torch, directing the flame to the exposed surface of the rolls as well as to the substrate or membrane underneath.
  6. Lap sides 75 mm (3") and ends 150 mm (6"); staggering end laps a minimum of 450 mm (18").
  7. Maintain approximately 10 mm (3/8") flow out of bitumen at overlapping seams.
  8. Roll seam to ensure complete bond.
  9. Carry membrane to the top of the cant. DO NOT BOND TO THE CANT.
  10. Reroll opposite end of the roll not torched and install in the same manner.
  11. For slopes exceeding 1:16 (3/4" in 12"), install membranes vertical to the slope and mechanically fasten in the head laps.


RUBEROID® CAP SHEET

  1. Start at the low point of the roof and perpendicular to the slope.
  2. Unroll 1.2 m to 2.0 m (4’ to 6’) and align membrane.
  3. Asphalt adhered: embed ply sheet(s) to suitable substrate in a full, uniform mopping of hot steep roofing asphalt at a rate of 1.2 kg / m2 (25 lb per 100 ft2).
  4. Adhesive adhered: embed membrane to suitable substrate in a full, uniform layer of modified bitumen adhesive applied at a rate of 0.8 L / m2 (1.5 gal per 100 ft2).
  5. Torch adhered (SBS Heat-Weld membranes only): torch apply to suitable substrate with propane torch, directing the flame to the exposed surface of the rolls as well as to the substrate or membrane underneath.
  6. Lap sides 75 mm (3") and ends 150 mm (6"); staggering end laps a minimum of 450 mm (18").
  7. Maintain approximately 10 mm (3/8") flow out of bitumen at overlapping seams.
  8. Roll seam to ensure complete bond.
  9. Carry membrane to the top of the cant. DO NOT BOND TO THE CANT.
  10. Reroll opposite end of the roll not torched and install in the same manner.
  11. For slopes exceeding 1:16 (3/4" in 12"), install membranes vertical to the slope and mechanically fasten in the head laps.


BASE FLASHING

  1. Asphalt adhered: embed ply sheet(s) to suitable substrate in a full, uniform mopping of hot steep roofing asphalt at a rate of 1.2 kg / m2 (25 lb per 100 ft2).
  2. Adhesive adhered: embed membrane to suitable substrate in a full, uniform layer of modified bitumen adhesive applied at a rate of 0.8 L / m2 (1.5 gal per 100 ft2).
  3. Torch adhered (SBS Heat-Weld membranes only): torch apply to suitable substrate with propane torch, directing the flame to the exposed surface of the rolls as well as to the substrate or membrane underneath.
  4. Lap sides a minimum of 75 mm (3").
  5. Ensure a bitumen flow out of approximately 10 mm (3/8").
  6. Consult GAF Application and Specification manual for specific flashing substrate requirements or additional flashing details.

2 Membrane Assemblies

2.1 Exposed Membrane - Un-insulated

Slope Limitation: 1:4 (3" in 12") Consult membrane manufacturer for installation at higher slopes
In-Service Performance: Min.: -10°C (+14°F)
Temperature of the Min.: -18°C (0°F)
Membrane: Min.: <-18°C (0°F)
Max.: +50°C (+122°F)

2.2 Exposed Membrane - Insulated

Slope Limitation: 1:4 (3" in 12") Consult membrane manufacturer for installation at higher slopes.
In-Service Performance: Min.: -10°C (+14°F)
Temperature of the Min.: -18°C (0°F)
Membrane: Min.: <-18°C (0°F)
Max.: +50°C (+122°F)

2.3 Protected and Modified Protected Membrane Assemblies

Slope Limitation: 1:4 (3" in 12") Consult membrane manufacturer for installation at higher slopes
In-Service Performance: Min.: -10°C (+ 14°F)
Temperature of the Min.: -18°C ( 0°F)
Membrane: Min.: <-18°C ( 0°F)
Max.: +50°C (+122°F)


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