Page 32 - Build 153

CROSS-FALL ON FLASHINGS AS SPECIFIED IN E2/AS1
BUILD
Flashing cross-falls
E2/AS1 speci es a minimum cross-fall for some ashings. Do you know which ones and how much?
RIGHT
BY TREVOR PRINGLE,
ANZIA, BRANZ PRINCIPAL WRITER
FOR SOME FLASHINGS, E2/AS1 speci es a minimum cross-fall to ensure water drains from the surface. Typically these are a minimum of:
● 15° for a head ashing to a window
● 5° for a balustrade or parapet cap ashing
● 15° for inter-storey ashings
● 10° for sill ashings to stucco and horizontal pro led metal.
Sill ashing on pro led metal
For the sill ashing to the top of direct- xed vertical pro led metal termi- nating below a window, E2/AS1 shows a slope to the part of the ashing capping the cladding. However, no angle is given.
cavity batten
cavity closure
folded stop-end
E2/AS1 transition tray ashing
Raking apron ashings
It is the same for raking apron ashings. A slope is shown, but the amount is not identi ed in E2/AS1 Figure 8.
A minimum cross-fall of 5° is suggested to ensure water drainage.
There have been problems
One area where a lack of cross-fall has caused problems is with raking apron ashings. A cross-fall may appear unnecessary because of the roof slope, but without it, water draining down the surface of the ashing can be trapped and held by the metal stop-end. Water trapped with dirt and dust creates the potential for corrosion.
cladding
apron ashing 10° minimum cross-fall suggested
roo ng
gutter
fascia
30 — April/May 2016 — Build 153