I am building a double story house. It is under construction.

I have bathrooms in the second story house which has showers. House frame is made of wood. I have hebel flooring.

My concern is about the waterproofing
Metricon builder has fitted the cabinets in the bathroom before the waterproofing has been done. I have shower in the bathroom in the second floor. So after waterproofing has been done in the bathroom the following areas has not been waterproofed

1) Floor below the cabinets which will have basins is not waterproofed
2) Walls behind the cabinets has not been waterproofed where the taps will be fitted
3) Drainage below the cabinets has not been waterproofed between the drainage pipe and floor.
4) Joints of all the walls and floors below the cabinets has not been waterproofed

Please let me know what is the correct standards to do the waterproofing.

Question by:
Anoop Sanghi's picture
Anoop Sanghi


Thanks for sending through your question. We asked Andrew Golle, the managing director of Armont Rectification Builders. See his answer below.

It is not necessary to waterproof beneath or behind the cabinets, according to AS 3740-2010, under the following conditions:
1. Wall junction at basin to be waterproofed, as per Table C1. This would be a sealant connection from the cabinet to the wall substrate, prior to tiling, in order to prevent moisture from travelling behind the cabinet through porous tile and grout. The splashback tiling silicone does not count, as it is topical.
2. Type 4 junction sealant connecting the floor membrane to cabinet kickboard, under a compatible sealant connecting water resistant hebel to non-water resistant kick board. This prevents the passage of water beneath the vanity through the tile line.
3. It is not necessary to provide a floor waste beneath the cabinet for overflow as Scope 1.1 states that the Standard does not cover situations where flooding occurs through overflowing of vessels and showers or plumbing failure.

The home owner should request that the above requirements have been put in place and be documented on the water proofing certificate. I am not aware of the state or territory, where the build is occurring, as each state has different requirements for issuing a compliance certificate.

If you would like to send through a copy of the plan, Andrew has agreed to have a look at it to better understand the type of shower and comment further.

Hope this helps!

The BUILD team.