Underfloor heating installed on a suspended timber floor

audrey01

Does anyone out there have any recent experience of having a wet underfloor heating system installed on a suspended timber floor?

We are currently renovating our house (i.e. everything gutted, sound insulation, external wall insulation, side and loft extension, etc.) and we would like to install underfloor heating in the newly open-plan ground floor space. We would remove all the original floorboards, insulate the void between the joists (with Celotex or Kingspan), lay back the floorboards, lay plywood sheet 18mm, then UFH pipes, then finish with engineered wood. But this would require the whole floor level to be raised quite a bit, which would cause problems with the first step of the staircase in the entrance hall, I would imagine.

We have searched the internet for a solution that doesn't involve raising the floor that much and still give us the best heat output. We came across things like "UFH panels placed between the joists", or "wood floor directly on a screed with pipes", but we are not sure if the Celotex insulation between the joists would be strong enough to support the weight of a cement layer.

Has anyone got any direct experience of what solutions might work best? We're planning to have engineered wood throughout. Many thanks!

dyrniboy

Hi,

Go on the uponor website or any other good manufacturer of pipe for UFH.

http://www.uponor.co.uk/~/media/countryspecific/uk/download-centre/technical-manual/pex20-fact-sheet-timber-suspended-sprung-battened-floor.pdf?version=1

I am not in any way involved with an UFH company. Hope it helps !

Apologies if I have broken any forum rules

daveyjp

Is there a reason you want to do it this way rather than simply rip out all the timber floor and install UFH in a new concrete floor?

southcoastrgi

clicky

........

Hintza

We built our house a couple of years ago and initially had UHF (GSHP) specced for both upstairs and downstairs for a number of reasons we changed to radiators upstairs.

Cost being the primary reason and on a new build that would be a lot cheaper than on a renovation.

Biggest question though will be, do you really need heating upstairs? We were too chicken and put in radiators but the heating is never on. With the exception of towel warmers and sometimes to dry something.

Having said that I suspect we would put them on if we had a prolonged cold spell like we had 2009-10.

audrey01

Thank you for your feedback.
Interesting, our builder has also mentioned the Nu-Heat LoPro10 product, so we may go for that one.

@Daveyjp - what do you mean by ripping out all the timber floor and replacing it with concrete floor? we have a suspended timber floor and the void underneath is a good 50-60cm. Our builder thinks the joists will not be able to support screed with pipes UFH products unless properly re-inforced.

To make things worse, the joists run perpendicular to the main windows, and we were planning to run the engineered wood the same way (i.e. lay the floorboards in line with the light through the main windows to the room). So, our builder now says we definitely need to have some form of plywood above the joists that would run across them, then have the Nu-Heat UFH, then engineered wood on top.
Is this sensible?

Hintza

audrey01 wrote: »

Our builder thinks the joists will not be able to support screed with pipes UFH products unless properly re-inforced.

We were going to have to upgrade the joists too, which would have been fine in a new build but on a renovation?

You seem fairly determined to go down this route, you really need to sit down and work out the energy efficiency of the house and a cost benefit analysis.

MX5huggy

hat do you mean by ripping out all the timber floor and replacing it with concrete floor? we have a suspended timber floor and the void underneath is a good 50-60cm.

Perfect for swapping from a timber floor to a solid floor, you make the floor up something like 150mm of subase then a DPM, 150mm concrete 200mm of insulation (can be cheaper insulation as you have the depth) then 70mm of screed with the underfloor pipes in it. Total depth 57cm's

daveyjp

Even with a 50-60cm void you can still take out the whole of the floor then back fill the under floor void with suitable recycled aggregate, such as crushed bricks. This base is then used as a base for the new damp-proof membrane and new concrete floor housing the UFH.

If your builder isn't suggesting this I'd be asking him why.

This picture shows the finished job, the fill is labelled 'E'

http://hampshireunderfloorheating.co.uk/underfloor_heating/underfloor1heating-installation/underfloor1heating-installation.jpg

System

daveyjp wrote: »

If your builder isn't suggesting this I'd be asking him why.

maybe the builder thinks the costs and time involved with retrofitting a solid floor would outweigh any benefits at all?

It really is a significant outlay to remove a suspended timber ground floor and then rebuild a solid slab in it's place, all sorts of issues with services/structure... this is why there are specific products designed to be used on suspended timber floors

Hintza

It has just dawned on me you are talking about the ground floor, my apologies.