electric UFH and insulation question

[Mark B]

Hello,

I have been asked to install 450x450mm porcelain and electric UFH on a wooden bathroom floor.

In order to minimise any increase in the finished floor level I'm intending to remove the existing chipboard flooring and relay using 25mm WBP ply and then lay the UFH and tiles straight on top.

Having looked at a number of UFH manufacturer websites they all seem to recommend using an insulating board under the UFH element.

Has anyone tried insulating between the joists under the flooring board?

I was wondering if fixing something like 50mm Celotex between the joists would improve the efficiency of the UFH similar to fully boarding the floor.

I would fix battens to the joists so the Celotex sits level with the top of the joists to still allow air circulation beneath the floor.

Mark

 

[DHTiling]

hi mark..you need to leave ventilation under the boards.....just use a 6mm insulation board.....something like marmox or wedi.......but make sure the subfloor is solid.........

 

[wayne]

lux make a 4mm insulation board. get it at n&c tilestyle

 

[Mark B]

Hello,

I have been asked to install 450x450mm porcelain and electric UFH on a wooden bathroom floor.

In order to minimise any increase in the finished floor level I'm intending to remove the existing chipboard flooring and relay using 25mm WBP ply and then lay the UFH and tiles straight on top.

Having looked at a number of UFH manufacturer websites they all seem to recommend using an insulating board under the UFH element.

Has anyone tried insulating between the joists under the flooring board?

I was wondering if fixing something like 50mm Celotex between the joists would improve the efficiency of the UFH similar to fully boarding the floor.

I would fix battens to the joists so the Celotex sits level with the top of the joists to still allow air circulation beneath the floor.

Mark

Thanks for your comments.

As I was already intending to replace the sub floor I guess I could use 18mm WBP instead of the 25mm and then over board that with a thermal board then there would be no increase in the overall floor depth!

Mark.

 

[Varley]

The insulation boards are not vital when installing ufh on a wooden floor, I would say the 18mm ply would be fine, the insulation boards are more of a necessity on concrete substrates. Use insulation boards on wooden floors if you can, but if raising the height of the floor is a big issue then personally I wouldn't bother.

 

[DHTiling]

It is not as necessary to use insulation boards on timber as it is with concrete but it will still increase the warm up time and reduce the running costs........

 

[ralsmith1]

You really need insulation. Elec underfloore heating is expensive enough anyway - without your heat sapping into the floor.

I would put in a minimum of 20mm. Do as you said by replacing the 18mm with 22mm. Also speak to your client. Ask if you can add another 16mm to the floor depth. Explain why and I am sure they will not mind losing the 16mm - even if the ceiling is low. I wouldn't - save a fair bit of money over the next 15 years or so.

 

[faithhealer]

Marks post was a year ago so I hope it's fitted by now! lol

 

[ralsmith1]

 

[Mark B]

Thanks for the post.

As Faithhealer has spotted the original enquiry was last year. I went with just the 25mm WBP in the end as I wanted to make sure the floor didn't move. The floor and heating has been down for all this time and has been working extremely well.

Mark.