Looking for suspended floor UFH advice...

[Adam182]

Hi everyone, going to tackle installing wet UFH throughout the groundfloor during my current renovation and just looking for some advice really.

Joists are 110mm x 55mm @ 400 centres.

There is a 4 foot void underneath the whole house with supporting walls mid way underneath the floors in each room leaving the largest joist span in the kitchen/diner @ 1.7m and the lounge @1.9m.

Finished flooring will be engineered wood direct to joists.

I have 75mm celotex that will be sat in-between the joists on battens and then foamed/taped.

I have narrowed down my options to either leave a 15mm gap above the celotex and use aluminium spreader plates to sit the pipe into OR leave a 25mm gap and fix pipe direct to celotex then fill with a 8:1 biscuit mix.

Does anyone know if it sounds like my joists will be able to take the additional weight of the biscuit mix?

Using spreader plates will be more expensive and less efficient by the sounds of it from what I have read but the weight will be far less.

What would you guys do?

Thankyou any feedback is greatly appreciated.

 

[Dan Robinson]

Price isn't everything. Ambiente do a structural panel that holds the pipes.

 

[Doggit]

I wouldn't add a biscuit mix to 4 inch joists, so the spreader plates might be the only option. Spreader plates will actually heat up and cool down quicker than a biscuit mix, so provide a similar heating curve to radiators.

 

[dilalio]

When inexpensive doesn’t work, it’s expensive.
You need a system that best suits your floor construction and desired floor-covering.

 

[Adam182]

Price isn't everything. Ambiente do a structural panel that holds the pipes.

Thanks for the info Dan, as I already have the PIR insulation now, buying those panels would kill my budget.

I wouldn't add a biscuit mix to 4 inch joists, so the spreader plates might be the only option. Spreader plates will actually heat up and cool down quicker than a biscuit mix, so provide a similar heating curve to radiators.

Ok Doggit thanks for this, if you wouldn't do it on 4 inch joists then neither will I.

When inexpensive doesn’t work, it’s expensive.
You need a system that best suits your floor construction and desired floor-covering.

Nice little bit of wisdom there Dilalio. In your opinion what do you believe would best suit in that case?

Thanks for all the feedback everyone much appreciated.