To ensure protection against water entry into a
newly installed roofing system, membrane flashing shall be
installed at all primary membrane terminations (i.e. roof drains,
curbs, roof/wall junctions, parapets etc.) as the application of
the primary membrane progresses.
The use of cant strips at roof junctions is not
required for thermoplastic membrane systems.
The membrane flashing shall be uniformly
supported by and secured to an acceptable, solid substrate.
Acceptable substrates consist of minimum 12.7mm (1/2”) thick
plywood, minimum 11.1mm (7/16”) oriented strand board,
dimensional lumber, smooth concrete, smooth surfaced concrete block
or masonry and minimum 22 gauge flat sheet metal.
Factory-coated glass faced gypsum roof
board or cement board, both must be a minimum 6.4mm (1/4”),
are acceptable substrates for the application of fully adhered
thermoplastic membrane flashing when a minimum 12.7mm (1/2”)
thick wood sheathing is provided as a nailable support. Glass faced
gypsum board or cement board shall be suitably fastened into the
wood sheathing and/or parapet wall studs. Thickness subject to
approval from the authority having jurisdiction to meet
non-combustible requirements of the Alberta Building Code. (See
Stucco, cobblestone, textured masonry, and
corrugated metal panels are not acceptable substrate for the
application of thermoplastic membrane flashing and must be covered
by minimum 15.9mm (5/8") thick mechanically fastened exterior grade
The minimum height of the membrane
flashing at a wall, roof penetration, or curb shall be 200mm
(8”) above the primary membrane surface in a conventional
design and 200mm (8”) above the insulation or concrete paver
ballast material in a protected membrane or combination design. The
minimum height of membrane flashing at door sills shall be 100mm
(4”) above the primary membrane surface, or concrete paver
surface measured at the door sill location.
The maximum membrane flashing height is 1100mm
(42") above the primary membrane surface. A variance request must
be submitted to the Technical Committee when membrane flashing
height is to exceed 1100mm (42").
Where the upper termination of the membrane
flashing on a vertical surface is exposed to water entry, the edge
shall be protected with a continuous sheet metal flashing and
The tops of parapet walls not covered by
membrane flashing shall be covered with a water resistant sheet
extending down from the top of the blocking a minimum distance of
50mm (2”) on each side.
Sheet metal flashings shall be installed to
cover and protect the top (horizontal) membrane-flashing surface
unless otherwise approved.
Where required by the building code, metal
flashings shall cover the vertical surface of the membrane
Thermoplastic membrane flashing materials and
accessories shall be from the same manufacturer as the primary
P.V.C. membrane flashing shall comply with the
requirements of CGSB 37-GP-54M.
T.P.O. membrane flashing shall comply with the
requirements of ASTM D-6878.
The use of unreinforced thermoplastic membrane
is restricted to the fabrication of field wrapped roof penetration
flashing, such as circular pipe vents.
Thermoplastic adhesives and primers are
temperature sensitive and should be stored and maintained at all
times at temperatures between 15 - 27°C, (60 - 80°F).
The membrane manufacturer's cold weather
requirements must be followed for thermoplastic membrane
applications below 10°C (50°F).
When preservative treated wood components are
incorporated into a roof assembly, the potential for corrosion of
the some metal fasteners, sheet metal and roof decking exists when
in direct contact with non C.C.A. (Chromate Copper Arsenate)
Exposed penetrations through the membrane
flashing shall be placed no lower than 200mm (8”) above the
finished roof surface.