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Australian External Waterproofing Standards Amongst the Best in the World

Houston You Have a Problem!

by John Rathbone, current member of BD-13 Committee working on Australian Standards for Waterproofing

Well to be honest it’s not Houston, it’s a deck in Canada but balconies in all developed countries that have problems like the ones shown in the above photo, that was spotted by a Wet-sealer on holiday (we never sleep), for example no fall to outlets and no membrane covering the deck plus the post penetrations are not sealed.  My point is that there still seems to be many people in our own industry that are not aware that Australia doesn’t only have a Standard for Balconies but that it is now referenced in the BCA and that it has procedures to deal with every day problems. Please note:  If the Australian Standard is compared to External Waterproofing Standards in other countries it is seen to be superior due to the following:

  • It deals with problems that are encountered every day on roofs and balconies – European and American Standards assume that upstands will be sufficient and have no procedures for membranes below the door sills and the essential waterstop behind the door.
  • It is set out so that the procedures and requirements for each section are complete – one of the best External Waterproofing Standards from another country fails on this count as it contained too many detailed procedures interspersed with comments so that Builders and Certifiers have had difficulty complying with this Standard.
  • “Recurring problems are fully covered” – for example sealing of post penetrations which have been fitted after the waterproof membrane has been installed and the requirement for movement joints in tile installations, the lack of which has caused problems for many years.
  • waterproofing of planter boxes and satisfactory methods of drainage of boxes are shown.
  • a suitable method for waterproofing sliding door sills where the deck or balcony is required to be level entry – this style of balcony is becoming more and more popular, the ageing population being a significant driver of this change.
  • the requirement that all membranes must be tested (see AS 4654-1)
  • overflow pipes/outlet must be the same diameter as other drainage pipes used on deck and tiled finish must not restrict the design flow of the outlet


Be Alert – Not Awash!

Waterproofing Requirements for Rimless and Stand Alone Baths

by John Rathbone, current member of BD-13 Committee working on Australian standards for Waterproofing

New Zealand was the first country in our area to strike problems with these baths.  The first wave of imports were “budget baths” which could be produced cheaply, as rimless baths.  They are less complex moulds than standard baths, so production is quicker.  They were installed against the wall sheets with the shower over the bath.  Shortly after the shower went into service the problem became apparent – water from the shower rose was penetrating at the junction between the wall sheet and the bath, damaging the bathroom floor.  Various “band aid” solutions have been tried with no success.  This caused our Waterproofing Committee to introduce a new procedure in the 2010 edition of AS 3740 to address this type of bath which at the time was marketed in Australia.

However, since then many new types of rimless and free standing baths are being marketed in Australia.  Many of them are often installed under showers, with resulting damage to the bathroom floor and water penetration to adjacent rooms.  The committee has addressed this problem in AS 3740 amendment one (re-issued 12/12/2012) which was referenced in May 2013 in, by the National Construction Code (NCC).

The updated requirements for rimless and free standing baths where there is a shower fitted above the bath are as follows:

For both types – the floor of the bathroom must be waterproofed and drained to a waste.

  1. A rimless bath with shower over is treated as  type two shower (e.g. the waterstop shall be a minimum of 1500mm from the wall connection of a shower rose** and must finish flush with the finished surface of the floor.
  2. Waterproof the whole bathroom floor (including waterstop in the bathroom doorway)

** I should point out that in bathrooms this method is very rate, as home owners don’t like seeing the top of metal angle in their tiled floor, so invariably the second method is chosen (e.g. the full bathroom floor waterproofing and the waterstop is in the doorway as shown in AS 3740-2010 (amendment No. 1) on page 19.

(I was in Europe a few years ago where rimless baths below showers are very common, and nearly all that I came across were leaking like sieves).

Australia can avoid this expensive mess simply by following the new requirements (and by always using a professional to install the waterproofing).