the external waterproofing membranes...

AS 4654 -2

The External WaterproofingMembranes

Standard

This external waterproofing standard containssolutions for problems which have not beenaddressed in other countries.

NOTE

• Any material used for external waterproofing systemsshall comply with AS 4654.1.

• In the past membranes which have passed tests inother countries have been found unsuitable for use inAustralia.

CONFORMANCE CONDITIONSAS 4654-2, Page 6, Para 1.6

Table 2.1Requirements – Fully Bonded Membranes

• No up stand for membrane.

• No fall in deck to shed water to wastes.

WATER PENETRATION AT SLIDING DOORS

• All falls shall ensure that water drains to outlet/s orgutters.

• Water shall not pond on the finished surface.

• Falls shall be in the structural substrate or as analternative the fall can be formed by a screed (NOT AMORTAR BED).

FALLS TO WASTESAS 4654-2, Page 8, Para 2.5.2

Concrete surfaces must be primed to resist “gassing” which can damage membranes

• The surface of the substrate shall be clean and dry.

• Moisture content of concrete screed shall not exceed7%.

• To aid adhesion on concrete surfaces smoothnessshould be the same as wood float or rough power toolfinish.

SUBSTRATES FULLY BONDED OR LIQUID APPLIED

AS 4654-2, Page 9, Para 2.5.3.1

The common problems

UPSTANDS

Deck set higher than internal flooring – no water stop fitted

Tile bed higher than waterproofing upstand ……a very common problem

• The height of the up stands are related to the degree ofrisk involved. In cyclone areas and exposed positionsup stands must be higher than buildings which are insheltered positions

• The higher the building the higher the upstand (e.g.the upstand would be 40mm higher in a building whichis above 15 metres).

TABLE ONE: RATIONALE

• This enables the sill to be tanked and will not delayconstruction as the remainder of the waterproofing canbe installed at a later date.

DOORS & WINDOWS MUST BE REMOVED PRIOR TO

WATERPROOFINGAS 4654-2, Page 17, Para 2.8.3.(A)

Figure 2.8 (in part)Typical Detail of Membrane Termination at External

Opening Doors

• Many manufactures now produce suitablesliding doors for level entry decks.

LEVEL ENTRY DECKS

WATERPROOFING FOR DECKS THAT REQUIRE LEVEL ENTRY

PARAPET PROTECTION

Common problems are:

• Upstanding angles at edge of decks.

• Angles that allow storm rain to penetrate asvertical leg is too short.

• High front gutters.

GUTTERS

Water retained by steel extrusion – tile bed became saturated & water leaked through sheet joints & fasteners

• The vertical leg of the angle must be a minimum of35mm.

• Sheet membranes must terminate on a horizontalsurface.

• Liquid membranes must terminate on a verticalsurface.

GUTTER TERMINATIONS

TYPICAL GUTTER TERMINATION DETAIL

• Planter boxes shall be drained with a vertical riser.

• The finished base of the planter box shall be graded tothe outlet.

• The membrane shall be sealed to a drainage flange,and shall continue to the top of the box and over theedge of the planter box.

• Where a wall is adjacent to the box it shall beoverflashed or sealed to the planter box.

PLANTER BOXES(Key Requirements)

TYPICAL PLANTER BOX CONSTRUCTION

• Timber posts should be installed in saddles (so thatposts can be replaced without damaging thewaterproofing).

• On concrete decks post bolts penetrations should betreated with epoxy.

POST AND POST SUPPORTS

TYPICAL DETAIL OF METAL POST SUPPORT –PRIOR TO MEMBRANE INSTALLATION

Posts that are fitted after waterproofing has beencompleted shall be sealed.

POST SEALINGAS 4654-2, Page 20, Para 2.8.4

• Building coatings must be waterproof, and I draw yourattention to the “leaky building” syndrome in NewZealand. In many cases water penetrated into thebuilding envelope because the coatings were notflexible enough to withstand quite minor buildingmovements.

WATERPROOFING ABOVE TERMINATIONSAS 4654-2, 2.5.1.4

The finished floor level shall not reduce the design flowof the outlet, and the outlet pipe should be the samediameter as the risers that drain the roof/balcony.

OVERFLOW PIPESAS 4654-2, Page 27, Para 2.1.1

Drainage holes are too small & are set up from the surface of the deck

Entry to drain 50% blocked by finished tile surfaceAS 4654-2, Page 29, Fig. 2.8 (C)

TYPICAL DETAIL OF OVERFLOW PIPE

Upward termination of the membrane is to be inaccordance with Table A1 appendix A (e.g. above thefinished surface of the roof).

SKYLIGHTS

Movement joints shall be provided in the topping toaccommodate movement in the membrane.

BONDED SYSTEMS(e.g. TILES)

For other than loose laid materials, movement joints mustbe carried through to and into the surface finish.

MOVEMENT JOINTS IN THE SUBSTRATE