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DESIGN
Flashing openings in masonry veneer
Correctly flashing openings in masonry veneer is the first step to ensuring weathertightness.
RIGHT
BY ALIDE ELKINK,
FREELANCE TECHNICAL WRITER, WELLINGTON
MASONRY VENEER comprises about a third of
the domestic external cladding market. With its common usage, it is important to understand the speci c requirements for ashing openings in masonry veneer.
Flashings to openings generally
Openings in the timber or steel wall framing must have the following:
● Flexible wall underlay cut and dressed into
the opening on all sides (or, for proprietary RAB systems, follow the speci c installation details).
parallel chord truss lintel
exible ashing tape applied to top corners of opening
100 mm
wall underlay turned into opening all around
100 mm 50 mm
exible ashing tape across full width of the sill trimmer
● Flexible ashing tape applied to the top ivot) door model
model corners of window and door openings and
900 extended 100 mm from the corners both
426 170
del
1000 x 1000 00 x 900
both sides. A layer of wall underlay or exible ashing tape must be lapped over the exible ashing (see Figures 2 and 3).
● Flexible sill ashing across the sill, folded into
the opening and down the face of the wall
underlay and over a tilting llet to provide a
be extended 200 mm beyond the jamb line on
both sides (see Figures 4 and 5).
● Flexible jamb ashings attached to the window jamb section and xed on both
sides of the opening for the full height of the opening, clout- xed over the wall underlay so
moisture is directed to the outside face of the
cladding (see Figures 4 and 5).
Rigid head flashing
BRANZ also recommends installing a rigid head ashing with a minimum 15° slope and stop-ends abutting the brick jambs for both aluminium
x 900
horizontally and vertically (see Figure 1). ● Flexible ashing tape applied across the
full opening width of the sill and extended
vertically 100 mm up the trimming studs under
the jamb battens (see Figure 1).
trimming studs
Figure 1
sill trimmer
900 x 900
00 ● Flexible head ashing across the opening,
oor model bedded into the mortar joint above the opening and extended 200 mm beyond the jamb line on
Flexible wall underlay and exible ashing tape turned into a steel-framed opening with thermal break strips.
900 x 900
kick-out to give a drip edge. The ashing must
REQUIREMENTS FOR FLASHING OPENINGS IN MASONRY VENEER
50 mm
thermal break strips under wall underlay
100 mm
50 mm
448
900 170
426
448
630
635
635
635
Build 161 — August/September 2017 — 39