Am I worring too much about the subfloor?

[ADringer]

Hi,

 

I'm in the process of getting wet UFH installed upstairs. The current buildup is 100mm of insulation between the joists and then spreader plates on top.

 

Most of this will be carpeted with the exception of the bathroom and en suite which will be tiled.

 

My builder is planning on putting 20mm ply down, but can't help wondering if there are any better alternatives to ply that will help conduct the heat but also be structural enough?

 

I had a look at Hardie backer but from what I understand that's not structural so would still need ply.

 

Is there something else I can look at, or am I worrying over nothing and the ply will be fine?

 

Thanks!

[markc]

20mm ply? Guessing you mean 18mm. Most floors are 18mm or 22mm chipboard with is cheaper and comes with tongue and groove joints on all edges.

ply would be fine but why use it?

[ADringer]

Yep probably meant 18mm! I'm sure the builder said ply but could be wrong. Would 18mm chipboard be fine as the subfloor with UFH underneath it? 

[TonyT]

What’s the design of the UFH say?

is the builder installing the heating system too?

if so good,

if not best talk to the plumber as each layer acts as an insulator