Hardie board for new bathroom

[sankara]

Hi Team

I am planning for a new bathroom which will be framed, roofed, floored and wether board cladding by a builder. i choose to finish the internal.

1.I am planning on 6mm villaboard lining on the internal studs for wall. insulate with batts

2. 6mm ceramic tile James hardie underlay on top of particle or plywood subfloor

3. i would double up to raise the entire floor and so i can create a slop in the walk in bathroom by screeding  down towards the drain 

4 tiling all floor area and walls up to the ceiling

the questions are

1. do i need water proofing. is it on or under the cement board. i could not find a instruction or video to waterproof or not to on a cement board when used as bathroom floor or under tiled shower area

2. is the thickness of the board appropriate for the wall or do i need a some kind of backer board

[JDE · Accepted solution]

Sankara

Yes you definitely need a waterproof membrane. It goes over the cement sheeting under the tiles. If you are getting the job signed off by council you need the waterproofing done by a professional (denfinitely where I live so check). If not after sheeting the bathroom you will need to prime your sheets ( something like Dunlop Multipurpose Water based Primer) some tape for corners and joints, and waterproofing membrane (Dunlop Undertile Waterproofing) it comes in a bucket and you paint it on. Bunnings has the mentioned products and the equivalent in a couple of other brand its not cheap about $230 for a 15l bucket. Make sure you put on the minimum 2 coats with stroke direction at right angles between coats and double that on corners. There is a video on waterproofing a bathroom on the Bunnings how to website.

Re the thickness check Mitchell's response to question "Villaboard for wet areas 1/4" or 3/8"? For a full answer  His answer was yes unless you are using really heavy tiles. 6mm is what I used when creating an ensuite in my wifes studio. The mentioned products are just the ones we used. JDE

[MitchellMc]

Hi @sankara,

It's great to see you're already receiving helpful advice from @JDE. As mentioned, you need waterproofing in your bathroom. Water will freely transfer through your grout and into the sub-floor without it.

These step-by-step guides will be helpful: 

• How to install tile underlay

• How to waterproof a shower 

• How to waterproof your bathroom floor

• How to lay floor tiles

• How to tile a bathroom wall

• How to grout wall tiles.

6mm Villaboard is standard for bathrooms unless you have minimal studs in the wall or are installing very thick wall tiles. Here are the James Hardie specifications.

Whilst you're still in the planning stage check out our Top 10 most popular bathroom projects for inspiration and this informative guide by @Adam_W on How to plan a bathroom renovation.

We'll be keen to follow along with your project and provide assistance where needed. Reach out whenever you have a question or get stuck. We're here to help.

Mitchell