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Serving Alberta's Roofing Industry Since 1961
BUR Section 8: Sheet Metal Flashing
Sheet metal flashings shall continuously cover
the membrane flashing installed at horizontal to vertical roof
junctions. Sheet metal flashings shall be installed as soon as
practical to protect the membrane flashing from damage.
Sheet metal flashings shall be corrosion
resistant. The metal finish is not warranted by ARCA Warranty Ltd.
Protect the metal finish from damage during shipping and
Oil canning of sheet metal flashing is a
natural phenomenon and is not cause for rejection. Severity of oil
canning can be reduced by one or more of the following means:
Use a heavy gauge metal that is more rigid
Use metal with low-gloss finish or textured by embossing or
striations to reduce visual effects
When the face exceeds 250mm (10 inches), fabricate flashings
in two pieces or use stiffening ribs, v-groove, or cross
BUR-8.2 Weights and Thickness
The weight and thickness limits shown in the
following table shall be followed within the CSA tolerances
designated for the metal type shown and does not include the metal
finish. The minimum weight or thickness of the sheet metal flashing
shown in the table must be increased to the next heavier dimension
when the unfastened vertical length of the sheet metal exceeds
457mm (18”), when measured from its main anchorage point.
||0.020 - 0.022
||0.50 - 0.56
||0.030 - 0.034
||0.76 - 0.87
Exposed sheet metal edges shall be hemmed and
shall not be left raw cut with the exception of field fabricated
joints found at corners. The top edge of the base flashing need not
be hemmed when covered by a cap flashing. Individual sheet metal
flashing pieces shall not exceed 3048mm (10 ft.) in length (Also
The ends of sheet metal flashings shall be
joined by S-locks or standing seams. S-lock flashing ends shall be
fabricated to permit an approximate 25mm (1”) insert, with a
tolerance of ±6.4mm (1/4”), in addition to an
allowance for the thermal movement of the sheet metal
Standing seams shall extend a minimum distance
of 25mm (1”) above the flashing surface and shall incorporate
a single lock fold.
The horizontal seams at corners shall be joined
with a double seam or a standing seam.
Vertical corner seams may be lapped and mitered
when not joined with a standing seam.
No soldering or caulking of joints is necessary
except where a watertight joint is required at miscellaneous sheet
metal flashing joints and where horizontal flanges attach to
BUR-8.4 Wall Flashings
BUR-8.4.1 Base Flashings
A two (2) piece wall flashing shall cover
non-granular surfaced flashing membranes, except where a one piece
wall flashing is permitted for Warranty Certificate issuance. The
sheet metal base flashing shall extend up the vertical substrate a
minimum distance of 200mm (8”) above the primary membrane,
cover the cant and extend horizontally approximately 25mm
(1”) from the toe of the cant over the membrane
Base flashings shall be mechanically fastened to
solid backing at intervals not exceeding 1500mm (5 ft.) centers,
with approved fasteners placed approximately 175mm (7”) above
the primary membrane.
BUR-8.4.2 Cap Flashings
The top of walls shall be covered with wood
blocking capable of providing sufficient holding force to anchor
nail and screw fasten cap flashings. Where membrane flashing does
not cover the blocking, a water proofing membrane shall cover the
blocking and extend down each side a minimum distance of 50mm
The cap flashings shall completely cover
the wood blocking and shall incorporate a minimum 50mm (2") wide
vertical face, excluding the drip edge.
The vertical face of cap flashings shall overlap
the wall finish and incorporate a drip edge to shed water.
Cap flashings shall be concealed fastened at one
end with galvanized roofing nails placed in both the horizontal and
vertical faces of the S-lock end joint.
On vertical faces the cap flashing shall be
mechanically fastened to the blocking with wood screws placed at
maximum 1500mm (5 ft.) centres.
Mid-fastening of cap flashing lengths
with screws may be substituted with sheet metal hook strips. Hook
strips shall be a minimum of 1/3 the length of individual cap
flashing pieces which are greater than 1500mm (5 ft.) in length.
The metal hook strip shall be a minimum of 24 gauge fastened at
maximum 300mm (12”) on centre into the vertical face of
continuous wood blocking. Spiral or ring shanked nails shall be
placed a maximum 25mm above the hook strip bottom kick- out. The
hemmed drip edge of the cap flashing piece shall be fully engaged
with the hook strip. High wind areas require special consideration
determined by the design professional.
BUR-8.4.3 Counter Flashings
For smooth surfaced walls, terminations,
membrane flashing terminations shall be covered with a reglet or
kick-out style counter flashing detail.
Counter flashings shall be fabricated with a
drip along their lower edges to shed water. Counter flashings shall
overlap base flashings by a minimum distance of 50mm
Counter flashings shall not exceed 100mm
(4”) in width, excluding the drip.
For reglet style counter flashings, the wall
reglet shall be straight, of uniform width ranging between 12.7mm
(1/2”) and 19mm (3/4”) wide and not less than 19mm
(3/4”) deep. The sheet metal counter flashing shall be
mechanically fastened in the reglet at maximum 600mm (2 ft.)
centers and the exposed reglet opening continuously caulked.
Where use of a reglet is impractical, a kick-out
style counter flashing may be used for smooth surfaced substrates.
Kick-out style counter flashings shall be mechanically fastened to
the wall at maximum 600mm (2 ft.) centers. Fasteners shall be
placed immediately below the kick-out. A continuous metal bar may
be incorporated to ensure wall contact is maintained. The kick-out
lip shall be continuously caulked with a compatible sealant tooled
to shed water.
BUR-8.5 Roof Edge Flashings
A metal flashing is required to finish, shed
water and protect the membrane flashing at roof edges.
The roof edge may be finished with a
cant edge detail or a parapet flashing.
Exposed fasteners are not permitted in the cant
area or on the horizontal/top flashing surfaces.
A gravel stop flashing detail is not
accepted for finishing BUR edges.
BUR-8.5.2 Cant Edge Flashing
For cant edge details, a sheet metal flashing
shall be fabricated to cover the membrane flashing installed over
the cant and extend horizontally approximately 25mm (1”) over
the primary membrane, measured from the toe of the cant. The
exterior vertical cant flashing face shall overlap the completed
wall finish and contain a drip edge.
Cant edge flashings shall be joined by S-lock
end joints and concealed fastened to the exterior and cant faces of
the wood cant strip with galvanized roofing nails placed in
flashing’s end joint flanges.
BUR-8.5.3 Parapet Flashing
Parapets shall be covered with a two (2) piece
metal flashing comprised of a separate base and cap flashing. Where
the parapet is less than 300mm (12”) in height, the base and
cap may be incorporated into a one piece flashing.
Where parapet cap flashings are required, the
top of the parapet shall be covered with wood blocking capable of
providing sufficient holding force to anchor nail or screw
Parapet cap flashings shall be fabricated to
completely cover the membrane flashing over the blocking and
incorporate a minimum vertical face dimension of 50mm (2”),
excluding the drip edge. The exterior vertical flashing face shall
overlap the completed wall finish. Parapet cap flashings shall
overlap base flashings by a minimum distance of 50mm (2").
Parapet flashings shall be concealed fastened at
one end using galvanized roofing nails placed in both the
horizontal and vertical faces of the S-lock end joint.
Additionally, the exterior cap flashing face shall be mechanically
fastened to the blocking with wood screws placed at intervals not
exceeding 1500mm (5 ft.) centers. Sheet metal hook strips, fastened
to the blocking, may be substituted for the wood screws (see
When the parapet width (girth) exceeds
400mm (16”), the maximum length of cap flashing piece shall
be 1500mm (5 ft.).
BUR-8.6 Control Joint Flashings
Roof control joints, either roof area dividers
or expansion joints shall be covered by a two (2) piece metal
flashing comprised of a base and cap flashing.
Where control joints are less than 300mm (12")
in height, the base and cap flashing may be incorporated into a one
BUR-8.7 Scupper Drains
Sheet metal scupper drains shall be sized to
extend beyond the exterior wall finish and to provide for a minimum
100mm (4") wide base, cant and wall flange formed at the interior
face of the scupper drain opening.
Through wall type scuppers must be four (4)
sided with the upper scupper opening surface covered with sheet
Where control of drainage is required, the
scupper assembly may include an exterior hopper and an attached
BUR-8.8 Miscellaneous Sheet Metal
Miscellaneous sheet metal flashings such
as roof jacks, gum boxes, ventilators, goosenecks and scupper
penetrations shall be watertight, incorporate a continuous one
piece deck flange, with no open corners, using a double seam or
approved lock to secure the deck flange to the vertical flashing
Deck flanges shall not be fabricated less than
100mm (4”) nor more than 200mm (8”) in width.
Watertight sheet metal flashing joints shall be
soldered or welded.
Watertight aluminum flashing joints must be
When approved, specialty flashings may be
substituted for fabricated sheet metal flashings.
© 2016 Alberta Roofing Contractors Association