Template:PERIMETER FLASHINGS - MEMBRANES (SBS)

1 General

Membrane flashing (stripping) details (with the exception of low parapets, cant strip edges and RGC accepted door sill details) must be designed to provide a minimum 200 mm (8") sealed height above the finished roof surfacing. Surfacing is defined as the top of the roofing assembly, be it membrane, ballast or growing medium (soil). All membrane flashing (stripping) terminating on a vertical surface must be mechanically fastened.

Curbed openings (HVAC, skylights, etc.) must be a minimum height of 200 mm (8") and have at least one ply of membrane flashing (stripping) carried to the inside edge of the curb, or up under the built-in counter-flashing of pre-manufactured metal curbs (i.e. roof scuttles or HVAC) (see Detail Reference here).

Parapet walls may be less than 200 mm (8") in height, but not less than 87.7 mm (3½") in height, refer to RGC Guarantee Standard A6.10.3 (see Details Section 10.3.2).

All cant edge and parapet wall details must have membrane flashing (stripping) that overlaps the exterior finish (i.e. wall cladding) by a minimum of 50 mm (2"). On high parapet walls, that are completely flashed with metal, where membrane flashing (stripping) is terminated part way up the wall the remainder of the parapet must be covered with a flashing underlay of a minimum 40 mils or 1 mm (.040") self-adhered modified bitumen membrane. No. 15 Felt is not acceptable (see Detail Section 10.3.1).

All stripping terminating on vertical surfaces must be mechanically fastened.

All membrane flashing (stripping) terminating at cladded (i.e. stucco, siding, etc.) walls must lap under the sheathing membrane and cladding by minimum of 75 mm (3").

All membrane flashing (stripping) terminating under a reglet must be sealed to the wall with a compatible mastic (see Detail Section 10.3.3). Where a parapet, cant or separation / expansion joint detail intersects with a higher wall; the membrane flashing (stripping) must be sealed by gussets (membrane saddles) that are formed to protect the inside and outside corners (see Detail Section 10.3.1).

New construction projects must follow proper sequencing. Where roof flashings overlap work by others (i.e. siding, stucco, etc.), this work must be complete prior to the installation of metal flashing or wood blocking must be installed to facilitate the future installation of the exterior wall finish under the cap flashing. When lapping under work by others (siding, stucco, etc.), the membrane and metal roof flashings must be installed prior to any wall coverings. Any variance to proper detail sequencing must be approved by the design authority in writing (see Section 10.3.3).

A reverse lap application method for base sheet and base sheet flashing (stripping), at roof up stand transitions, is permitted when self-adhered base sheet flashing is used as flame protection for wood surfaces. Use of the reverse lap method must be an acceptable application method to the membrane manufacturer.

If no published instructions are available, specific instructions in writing from the manufacturer must be obtained and filed with RGC before project start-up.

The roof system must be as per the complete tested assembly and a calculation for the building wind load requirements using the Wind-RCI calculator or Roofnav www.roofnav.comas applicable be submitted with project documents.

There is no minimum height requirement for exterior walls, (e.g. eave drip and gravel stop flashing)

2 Cant Strips

Wood: Cant strips are only required as recommended by the membrane manufacturer. The use of hemlock lumber for construction of cant strips and related blocking is not acceptable.

Fibre Cants: Only fibre cants manufactured from non-combustible materials i.e.: perlitic or fire-resistant fibreboard are acceptable for use on roof systems with torch applied membranes.

The self-adhered base sheet must extend a minimum of 150 mm (6") onto the roof surface. The heat welded field membrane must be turned up at the vertical surface a minimum of 100 mm (4") or a heat welded base sheet transition gusset extending 100 mm (4") onto the roof and upstand surfaces be installed.

Membrane gussets must be installed to all inside and outside corners.

Modified Bituminous Base Sheet pre-stripping ply required at all perimeters, upstands and penetrations. Cap sheet stripping is required and must extend 150 mm (6") horizontally and 200 mm (8") vertically from the base of all upstands.

3 Expansion and Control Joints

Roof Separation Joints (Expansion and Control Joints, etc.) / Equipment Sleepers / Safety Anchor Piers (poured in place pads) that are completely sealed (enveloped) with membrane flashing (stripping) may be less than 200 mm (8") in height but must not be less than 100 mm (4") in height above the finished roof surface.

Manufacturer’s proprietary roof expansion joint systems are acceptable for use when the systems are located a minimum of 200mm (8") above the finished roof surface and are completely sheathed (covered) with sloped metal flashing.

4 Door Openings

Door sill membrane flashing (stripping) may be less than 200 mm (8") in height but must not be less than 100 mm (4") above the primary roof membrane and must be installed to comply with the following conditions:

• A metal water stop flashing, formed with pan folded, welded or soldered corners must be mechanically attached to inside of door sill framing or opening and be sealed with membrane flashing (stripping).
• Membrane flashing, (stripping) or metal pan sill flashing must be installed at doorjamb framing or opening to a minimum height of 100 mm (4") above door sill framing or opening, prior to installation of doorjambs and door sills.
• Membrane gussets must be installed at sill corners.
• Metal pan sill flashings or RGC accepted reinforced liquid flashing systems must be installed wherever clearances preclude the use of membrane flashing (stripping) to seal door sill details.
• Slopes must be provided to direct water away from door sill details. (Overhangs are recommended wherever practical).
• Overflow drains in that area must be installed a minimum 25 mm (1") lower in height than adjacent door sills.

5 Built-in Membrane Gutters

When a built in membrane gutter joins an RGC Guaranteed sloped roof; the gutter will be included by the Guarantee. Built-in membrane gutters that drain a roof not covered by an RGC Guarantee are not eligible for a Guarantee.

Membranes installed as a gutter liner must be fully adhered and mechanically fastened at terminations. The accepted flexible membrane roofing system must be installed to RGC Guarantee Standards and the manufacturer’s printed instructions.

Built in gutter membranes must extend up the roof slope to a point, which is 150 mm (6") vertically above the maximum water level of the gutter or outside parapet height (see Section 7.5) “Built in Gutters for Water Shedding Roofing”).