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Serving Alberta's Roofing Industry Since 1961
BUR Section 3: Separator Sheets And Auxiliary Leveling Surfaces
BUR-3.1 Separator Sheets
Separator sheets are materials used to separate
roofing system components, to prevent material incompatibility or
to prevent adhesion.
BUR-3.1.2 Wood Decks
BUR-220.127.116.11 Uninsulated Systems
A separator shall completely cover wood decks,
as hot bitumen is not accepted for adhering BUR membranes directly
to wood decks for Warranty Certificate issuance.
For organic felt membranes, a separator
comprised of two (2) plies of No. 15 organic felt or one (1) ply of
a coated base sheet shall be nailed to the wood decking.
For fiberglass felt membranes, a separator
consisting of one (1) ply Kraft laminate nailed plus one (1) ply
fiberglass felt nailed is required.
Attach separator sheets using galvanized roofing
nails spaced at 150mm (6”) centres along the sheet edges and
300mm (12”) centres throughout the field of the separator
For O.S.B. and plywood sheathing decks, the
nails shall be long enough to extend a minimum distance of 12.7mm
(1/2”) beyond the lower surface of the decking.
For dimensional lumber decks, the nails shall
penetrate a minimum distance of 25mm (1”) into the wood
BUR-18.104.22.168 Insulated Systems
For conventional insulated BUR roofing systems
over wood decks, the vapour retarder membrane will serve as the
BUR-3.1.3 Concrete Decks
BUR-22.214.171.124 Cast-In-Place Concrete
A separator is not required when adhering BUR
membranes directly to cast-in-place concrete decks with hot
Hot bitumen may be used to adhere membranes to
concrete decks. Priming of the concrete surface with an asphalt
primer to improve adhesion is optional.
BUR-126.96.36.199 Precast Concrete
A separator is not required when adhering BUR
membranes directly to precast concrete decks with hot bitumen
except at deck joints.
Where joints between precast concrete deck
sections are grout filled, a separator sheet shall cover joints.
Installed dry, a 150mm (6”) wide strip of coated base sheet
shall continuously cover the grouted deck joints.
When precast deck sections do not contain grout
keys, continuously cover joints by installing a one half (1/2) roll
minimum 457mm (18”), width strip of a coated base sheet.
Adhere one side of the separator sheet to within 150mm (6”)
of the deck joint centre line with asphalt.
BUR-3.1.4 Steel Decks
Hot bitumen cannot be used to adhered BUR
membranes directly to steel decks.
An auxiliary leveling surface is required in
place of a separator sheet for uninsulated systems.
BUR-3.2 Auxiliary Leveling
An auxiliary leveling surface is a material used
to provide a smooth substrate to which roofing system components
can be adhered.
ARCA accepted auxiliary leveling
surfaces may be comprised of a minimum 9.5mm (3/8") thick Fibre
Reinforced Gypsum Panel (ASTM 1278), 12.7mm (1/2") thick Glass Mat
Gypsum Substrate (ASTM 1177), 12.7mm (1/2") thick Gypsum Board
(ASTM C1396), 12.7mm (1/2") Fibre-Mat Reinforced Cementitious Board
(ASTM 1325), 12.7mm (1/2") thick plywood, or 12.7mm (1/2") thick
O.S.B. when not used as a thermal barrier.
The existing substrate type and condition will
determine the auxiliary leveling surface type and attachment
Where required by the Alberta Building Code, a
thermal barrier may be used as an auxiliary leveling surface.
BUR-3.2.2 Wood Decks
For dimensioned lumber decks an accepted
auxiliary leveling surface shall be mechanically fastened to
completely cover the lumber decking, as BUR membranes cannot be
adhered directly to wood decks with hot bitumen.
For uninsulated four (4) ply BUR primary
membrane systems over wood sheathing decks, a minimum 12.7mm
(1/2”) thick fiberboard or gypsum board auxiliary leveling
surface shall be mechanically fastened to the O.S.B. or plywood
When using roofing nails for attachment, use a
minimum of one (1) nail per square foot of surface area.
When using drywall screws for attachment, use a
minimum of twenty (20) per 1200mm x 2400mm (4’x8’)
sheet or a minimum six (6) screws for 600mm x 1200mm
Follow Factory Mutual (FM) requirements when
using screws and plates.
BUR-3.2.3 Steel Decks
For uninsulated and protected membrane designs
an accepted auxiliary leveling surface shall completely cover the
steel decking prior to membrane application, as BUR membranes
cannot be adhered directly to steel decks with hot bitumen.
The auxiliary leveling surface may be attached
to the steel decking using one of the following attachment methods:
Continuous beads or a full roller coating of an acceptable
adhesive applied to the top flanges of the steel deck in accordance
with the adhesive manufacturer’s application rates.
Minimum twenty (20) self tapping drywall
screws per 1200mm x 2400mm (4’x8’) sheet fastened
through the top flange of the steel decking. Where drywall screws
break the gypsum board paper covering, install a replacement screw
in approximately the same location. Additional fasteners may be
required to meet wind uplift standards.
When using screws and plates for attachment, use a minimum of
eight (8) per 1200mmx2400mm (4’ x 8’) sheet fastened
through the top flange of the steel decking. Additional fasteners
may be required to meet wind uplift standards
Attachment method (b) for steel deck is experienced based. ARCA
has not conducted formal wind studies.
BUR-3.2.4 Concrete Decks
An auxiliary leveling surface is not required
over concrete decks as BUR membranes may be adhered directly to
concrete decks with hot asphalt.
Damaged and deteriorated concrete decks shall be
repaired to provide a smooth substrate for roofing system
© 2016 Alberta Roofing Contractors Association