Wooden Floor Preparation for Tiling

[It's me]

We are planning to tile our bathroom floor: I have seen so much conflicting information that I am confused and should like to try and get some clarity before starting.

We have sound wooden floorboards. My plan is to do the following on top of the boards:

- 6mm Hardie board (from Topps Tiles)
- underfloor heating mat
- tiles

My questions are:
1. Do I need to use adhesive and screws to fix down the Hardie board or just screws? I have seen both methods recommended.
2. Do I need an insulation board on top of the Hardie board or can I just put the heating mat onto the Hardie board? Again, I have seen both recommended.

I should appreciate advice, please.

Thank you.

James.

 

[drives]

Regarding the hardiebacker board fixing, I would do both- use your tile adhesive and then the 25mm screws as per the instructions.

 

[It's me]

Thank you, drives.

 

[Eccles]

Don't do it at all is my advice or you will soon regret it. It only really works well with solid floors.

 

[drives]

Not sure about that. That’s why products and installation methods exist for wooden subfloors. I’ve done it a number of times with ply overboarding and no problems have arisen, albeit times have obviously moved on with better products such as hardiebacker. I tiled our hallway a couple of years back using the above method, with no issues.

 

[Honj]

I used the 6mm Hardie boards over my chipboard bathroom floor and has worked really well for me. I didn't glue them down, just used the screws. Tiled over the top with thick porcelain tiles and has been fine for 7 years or so.

My only regret is not fitting underfloor heating.

Insulation board would certainly help with heat loss though floor space but might cause height issues for finished floor. If I was doing it again I would consider Wedi board as an alternative to the Hardie board.