Template:ROOF PENETRATIONS and DRAINS (SBS)

1 General

Flanges - All roof flanges in contact with asphaltic membranes of any type shall be primed both sides with membrane manufacturers approved primer and embedded in a trowel coating of compatible mastic. Flanges are to be a minimum of 100 mm (4") wide.

Lead flanges in contact with asphaltic membranes of any type shall be embedded in a trowel coating of compatible plastic cement. Priming is not required.

All vent plumbing flashings shall be constructed of non-ferrous material.

All roof protrusion and penetration flashings, vents, curbs, sleepers, pipes cable, drains, etc. shall NOT be installed LESS than 200mm (8") from the base of walls, cants, eaves and other roof equipment, protrusion and penetration flashings. The exceptions are overflow drains and roof scuppers that are installed through walls. These items are to be located by others.

2 Gum Pans (Sealant Pockets)

With the exception of one on-site formed double standing seam corner joint and adjoining lapped flange joint, all flange corners shall be closed and soldered. Use only membrane manufacturer’s approved proprietary urethane based structural sealants to fill gum pans or pitch pockets.

Install a back-up storm collar whenever practical (see detail Section 10.3. - new reference needed). This detail should be avoided; only use gum pans or pitch pockets as a last resort when other methods are impractical.

3 Strip-in Flashings

• must be a minimum height of 200 mm (8") above finished roof surfaces.
• are permitted only for use with single pipe roof penetrations and must incorporate properly fitted settlement caps.
• must be properly sized to fit pipe penetrations (Alternatively, when pipes are irregular in size, spray foam urethane insulation may be used to fill gaps between pipes and flashings.)
• may include strip-in type flashings for cables and multiple roof penetrations, provided such flashings are purpose-made.

3.1 STRIP-IN TYPE VENTS

• are permitted up to 350 mm x 350 mm (14" x 14"), equal to approximately 0.12 meter squared (196 sq. in.) on exposed or conventionally-placed membrane roofs, provided the vents are not located in or near a valley and are well drained.
• will not be permitted for use in protected or modified protected membrane roofs. Curb mounting for all venting units and equipment except lead or aluminum jacks is mandatory on protected or modified protected membrane roofs.

3.2 STRIP-IN CURBS

• are to be a minimum 200 mm (8") in height above top of finished surfacing.
• are to be supplied and installed by others.

All purpose-made multiple penetration flashings must provide a positive weather seal by use of manufacturer’s proprietary rubber based friction seals, mechanical clamps or gooseneck type design, and be a minimum height of 200 mm (8") above finished roof surfaces.

Metal wall base flashing is optional with these application methods.

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4 Roof Drains and Scuppers

Roof drains and other roof accessories are to be installed as per membrane manufacturer's instructions.

4.1 Drains

When cast-iron roof drains are used; a sump receiver and under-deck clamp must be provided and installed by the trade supplying the roof drain. In addition, the trade supplying roof drains must also provide secondary stainless steel debris strainers in addition to primary drain strainers on all roofing systems that utilize gravel ballast and or growing mediums (soil). Only the use of drain manufacturer’s proprietary secondary stainless steel debris strainers is acceptable.

All flange type roof drains shall be constructed of non-ferrous material. Flanged copper drains shall be formed from a minimum weight of 16 oz. sheet copper for external (on outside of walls) drains and 24 oz. sheet copper for internal (inside walls or buildings) drains. The minimum gauge for aluminium sheet to be used for roof drains shall be 20 gauge for external use and 12 gauge for internal use. In addition, the trade supplying roof drains must also provide secondary stainless steel debris strainers in addition to primary drain strainers on all roofing systems that utilize gravel ballast and or growing mediums (soil). Only the use of drain manufacturer’s proprietary secondary stainless steel debris strainers is acceptable.

4.2 Scuppers

Overflow scuppers shall be installed according to the British Columbia Building Code (BCBC).

Overflow scuppers are required when low doorway or window details are used, see standard A5.6.3

All roof scuppers shall be formed with a minimum 37.7 mm (1.5") lower outside faces than side walls of the water collection boxes and incorporate minimum 12.7 mm (.5") drip edges on the lowered outside faces.

On all re-roofing projects all drains connected to internal piping shall be connected by mechanical compression type seals only. “O”- rings, mastics and caulking are not acceptable methods to seal roof drains to internal piping.

Where no overflow scuppers are specified, the structure must be designed to carry the total load of water collected in the event of the failure of roof drains (See BCBC latest edition). RGC recommends overflow scuppers be installed where perimeter walls exceed 100 mm (4") in height and accepts no responsibility for roof failure where scuppers are not specified or installed.