Page 31 - Build 161

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E2/AS1 REQUIREMENTS FOR ROOF FLASHINGS
BUILD
Roof ashings
Flashings play a vital role in keeping water out of buildings. Follow this useful guide to check the requirements for roof ashings in Acceptable Solution E2/AS1.
BY ALIDE ELKINK,
FREELANCE TECHNICAL WRITER, WELLINGTON
THE TYPE of roof ashings required depends on what part of the roof is being ashed and what the roo ng material is.
Apron ashings
Horizontal apron ashings must:
● extend over pro led metal roo ng (see
Figure 1) for:
• 130 mm (excluding the soft edge) in low (L),
medium (M) and high (H) wind zones where the roof pitch is 10° or more – E2/AS1 Table 7, Situation 1
• 200 mm (excluding the soft edge) in L, M and H wind zones where the roof pitch is less than or equal to 10° – E2/AS1 Table 7, Situation 2
• 200 mm (excluding the soft edge) for all roof pitches in Very High (VH) and Extra High (EH) wind zones – E2/AS1 Table 7, Situation 3
● extend over clay and concrete tiles for 150 mm minimum and have the lead ashing dressed into the pans – E2/AS1 Figure 26(b).
Raked metal apron ashings must have tapered stop-ends to the lower end of the ashing to divert water away from the back of the upstand and into the gutter and have a 5° minimum cross- fall (see Roof-to-wall junction in Build 160). Metal tiles
Metal tiles must be installed with a 40 mm mini- mum upstand and a minimum over ashing cover of 35 mm – E2/AS1 Figure 35(b).
cavity batten
wall underlay
cladding
self-adhesive ashing tape
cavity closure
apron ashing to roof slope
roo ng
75 mm minimum
35 mm minimum
130 or 200 mm minimum (depending on wind zone and roof pitch)
roof underlay
Figure 1
bevel-back weatherboard
5° cross-fall roo ng
apron ashing and upstand with hem to upstand edge
Apron ashing at roof/wall junction – horizontal ashing.
wall framing
roof underlay
cavity batten
wall underlay lapped over apron ashing
cavity base closure
75 mm minimum cladding cover
110 mm minimum total
35 mm minimum gap
Figure 2
Apron ashing at roof/wall junction – parallel ashing.
Build 161 — August/September 2017 — 29