Page 26 - Build 151

GOOD DESIGN OF WATERPROOF DECKS
BUILD
Getting waterproof decks right
One area of building that can cause issues is having sufficient clearance between the bottom of the cladding and a waterproof deck.
RIGHT
BY TREVOR PRINGLE,
ANZIA, BRANZ PRINCIPAL WRITER
E2/AS1 HAS SOME SPECIFIC REQUIREMENTS that must be met for clearances between a cladding and a waterproof deck. These include:
● a maximum area of 40 m2
● a membrane upturn at the wall junction of at least 150 mm
● slope the membrane away from the wall
● lapping the wall underlay over the membrane upstand
● a clearance of at least 35 mm between the bottom of the cladding and the
highest point on the deck surface
● for claddings installed over a cavity:
• providing drainage from the cavity behind the cladding incorporating a cavity closure
• forming a drip edge (10–15 mm depending on cladding type) along the bottom edge
● a step down to the waterproof surface at doorways of 100 mm minimum (an alternative not detailed is for a 100 mm high threshold or step where the oor level and deck substrate are at the same level)
● a minimum deck slope for drainage of 2°
● no nish adhered to the tiles – any additional walk-on or protective
surface must be removable
● no downpipes discharging onto the deck.
In addition, it is considered good design of waterproof decks to:
● have a minimum of two drainage outlets, each with their own over ow
● specify ood testing on completion
● protect the membrane after it is laid.
Step 1
Construction sequence.
Step 4
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