Hardiebacker over floorboards

[Herbis]

Hi all,

Tiling my bathroom (wet room) floor, which will have an Impey tray.

I have wooden floorboards and planned to make sure they’re movement free then overboard them with 6mm hardiebacker, screwed 9 per board. Is this right? Do I need to put flexible adhesive underneath the hardie?

Thanks!

 

[Trigger]

Hardie used to state that the adhesive under the 6mm hardie didn't have to be flexible as its purpose is as a gap filler. I use flexible as its what I generally have to hand. They have an install guide on there website.

 

[Herbis]

Hardie used to state that the adhesive under the 6mm hardie didn't have to be flexible as its purpose is as a gap filler. I use flexible as its what I generally have to hand. They have an install guide on there website.

In that case, what’s your view on using gripfill as that’s what I have to hand (…I have a pack of 10 collecting dust)

 

[Trigger]

In that case, what’s your view on using gripfill as that’s what I have to hand (…I have a pack of 10 collecting dust)

My view is that the manufacturer doesn't advise using gripfill, it recommends tile adhesive.

 

[Herbis]

My view is that the manufacturer doesn't advise using gripfill, it recommends tile adhesive.

Good point, well made. In that case I’ll use tile adhesive. Priming - what do I use for wood? I also have 6mm hardie to go onto brick walls, I intend to use 6mm notched adhesive with 9 fixings per board - can I prime with the same as the floor? Waterproof PVA or other?