Backer boards onto ply

[Andy1978]

Hi guys,

I'm looking to tile my kitchen floor and install electrical UFH, my floor is 18mm t&g. I'm wondering if I can put down 6mm ply and 6mm backer board on top to create a strong footing and insulation. I've read about the flexible addy etc but concerned about the thickness needed, do different backer boards have stronger properties, if so which are the best?
I don't really want to put down really thick ply due to the height from hallway to kitchen so opting to use backer board.

Any replies will be great.

Thanks

Andy

 

[iwaters]

Just the backer boards should be amble. They have to be set with adhesive as well as being screwed down. Otherwise you could overboard with 15mm ply which wouldn't add much more height than you are currently considering.

Ply and backboards is not going to provide much insulation at all. I can't see a published U/R -value for hardibacker or aquapanel and thermal resistance is not its primary purpose - 1/2" ply has a u-value of 1.6 which is about as good as a decent double glazed window (i.e. not great) . You will need to lift the existing boards and lay celotex of rockwool or similar between the joists to get any real insulation.

 

[Andy1978]

Thanks iwaters for your feedback.
So would it be better to lay backer boards on top of my t&g and then an insulated board before UFH, then tile.

Thanks

Andy