How to set Villaboard joints in wet area?

[marric]

Hi There,

I am renovating a bathroom using James hardie villaboard on the walls.  I have read the installation guide and also the wet area guide and they seem to provide conflicting information.  

one suggests using base coat and tape on all joints whereas the other alludes to using flexible waterproof silicone in a 6mm gap between joints.

 Both obviously covered by waterproof membrane

what is the correct advice & recommended approach?  

thanks

Mark

[MitchellMc]

Welcome to the Bunnings Workshop community @marric. It's brilliant to have you join us, and many thanks for your question about installing Villaboard.

The confusion comes from the fact that the two Hardie guides are referring to different zones within the same bathroom. The Villaboard lining installation guide applies to areas that are not in the designated wet area, for example any walls that will be painted or otherwise not exposed to constant moisture. In those spots, you treat the sheets exactly like a standard lining board, which means taping the joints and setting them with a base coat, tape and top coat so the wall can be finished smoothly.

Inside the actual wet zone, such as a shower recess or any tiled area, you follow the wet area construction guide. In these locations, you do not set the joints with a top coat at all. The sheet junctions are filled with base coat and tape applied, then the membrane goes on. The 6 mm gap they refer to is simply the movement gap at floor level and in corners in a non-shower area, which is filled with a flexible polyurethane sealant rather than being taped or set. 

If you have any specific questions, the James Hardie technical team are really helpful and can walk you through it. 

Please let me know if you have any questions.

Mitchell
 

[marric]

Hi Mitchell, Thanks for the reply. That makes sense although not overly clear in the guides. What about other walls that are not in the shower that will be tiled? Are they recommended to be set as if they were painted ? I’m having tiles all round Thanks Mark

[MitchellMc]

Hi @marric,

You'll use a base coat and then the tape, which is the same as within the shower recess, except the shower recess gets a membrane over it.

Mitchell

[marric]

Hi Mitchell,

thanks for the advice.  1 final question.  In the shower the recessed joint between 2 horizontal sheet should also be filled only with silicone ?  Or set ?

thanks

mark

[MitchellMc]

For rebated joints within the shower, @marric, it is the base coat and then tape. It's only the corners in non-tiled areas that get the 6mm silicone joint.

I apologise but there seems to have been some confusion in the information I was provided previously, so I've gone ahead and edited my replies above to ensure anyone else reading the discussion see the correct advice.

To summarise:

• If you are painting the sheets, you should apply basecoat, tape and a topping compound to the joints.

• If you are tiling a non-shower area, you should apply basecoat and tape to the joints.

• If you are tiling the area in a shower area, you should apply basecoat and tape and then the membrane to the joints. This includes the corners.

For corners outside the shower area, you apply a 6mm bead of silicone.

Mitchell