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Wet-seal Invited to Speak on Waterproofing for Wet Areas at Building Surveyors Seminar

Wet-seal’s Head of Technical & Special Projects, Robert Rath, was invited to present his expert knowledge on waterproofing for wet areas at the recently held Building Surveyors Seminar hosted by CPD Solutions held in Queensland.

CPD Solutions are dedicated to providing quality continuing professional development (CPD) training to the building industry.  Experienced in specialised training services, they also provide training services to professional associations.  Their training sessions are practical, using quality speakers from the building industry; ensuring a high standard of continuing professional development while providing you with peace of mind.

The seminar was designed for Building Surveyors with a selection of excellent speakers to give them the opportunity to update their skills, ask questions and network with other professionals in the building industry.

The event was attended by approximately 100 Building Surveyors & covered a wide range of topics relating to the building industry.

Key points covered by Robert during his presentation were:

  • Internal waterproofing compliance with NCC & AS: 3740 2010 amended 2012.
  • External waterproofing compliance with NCC & AS: 4564.2 2012.

To view a copy of Robert’s full presentation regarding waterproofing for wet areas & compliance with the NCC please click on the following link:

Robert Rath – Waterproofing CPD Presentation


Waterproofing Behind Wet Area Tiles

Effective waterproofing is vital for tiled showers & splashbacks & is highly important to keep bathrooms, laundries, & kitchens generally in good condition.  Too often, poor waterproofing results in failures, leaks & costly repairs.  Even if you don’t do the job yourself, it is still important to know how far waterproofing should go.


Water escaping from a shower & from around a bath, basin or the like can remain unnoticed for long periods & cause serious damage.  Properly detailed & installed waterproofing is essential behind tiled surfaces with cement based grouts because tiling is not inherently waterproof, & failure of tiled surfaces is a common problem in New Zealand.


Building Code clause E3 Internal Moisture requires buildings to be constructed to avoid fungal growth on linings, water overflowing to adjoining units & moisture damage to building elements.  Acceptable Solution E3/AS1 does not specifically define a wet area, but uses the terms ‘subject to watersplash’ & ‘showers’ when defining wet area requirements.


Considering the risk of water damage, there are two types of areas:

  • Those subject to frequent & heavy wetting, such as showers & open shower surrounds, & splash areas around baths & basins.
  • Those subject to regular intermittent wetting, such as floors in bathrooms, kitchens & laundries & the walls behind baths, basins & tubs. Tiled entries also fall into this category when people enter the house during heavy rain.
  • For both these types of areas, BRANZ recommends tiles be installed over a waterproofing system except where the substrate is steel-trowelled or polished concrete.  (In E3/AS1, a waterproofing membrane is required for tiled shower enclosures where tiles are laid over an absorbent substrate such as fibre-cement or water-resistant plasterboard).


As good practice for tile finishes, BRANZ recommends the installation of a waterproofing membrane:

  • in bathrooms, kitchens & laundries, to all absorbent floor substrates.
  • in an open shower, to all wall tiles within 1.5 m of a fixed showerhead plus the length of the flexible shower hose – waterproofing should go to the ceiling where the showerhead is removable.
  • in an open shower over a bath, to all wall tiles as above or the length of the bath plus 300 mm for a fixed showerhead.
  • in an enclosed shower, to all floor & wall tiles – waterproofing should go to the ceiling where a removable showerhead is installed.
  • for baths, waterproofing should extend at least 300 mm above & beyond the top of the side & ends of the bath.
  • for basins, waterproofing should go at least 150 mm above & past the hand basin.


For more information, see BRANZ Bulletin 518 Wet area tile waterproofing.

Article source – BRANZ Builder’s Mate Publication, Issue 60.