Underfloor heating, suspended timber floor
Discussion
Hi,
wonder if anyone has an experience of wet underfloor heating between joists.
Our plan is to remove existing floor boards (which are a bit of a state anyway), kingspan between joists, then install underfloor heating pipes between joists. We seem to have a choice of screed or alloy spreader plates but not sure which is better.
Plan was to lay a solid oak floor back down once heating in, nailed back to joists. Concerned about restricting heat too much with the floor type and also worried about floor moving because of heating/cooling. Been suggested that engineered boards would be better but I'm not keen on them.
thanks for any input.
wonder if anyone has an experience of wet underfloor heating between joists.
Our plan is to remove existing floor boards (which are a bit of a state anyway), kingspan between joists, then install underfloor heating pipes between joists. We seem to have a choice of screed or alloy spreader plates but not sure which is better.
Plan was to lay a solid oak floor back down once heating in, nailed back to joists. Concerned about restricting heat too much with the floor type and also worried about floor moving because of heating/cooling. Been suggested that engineered boards would be better but I'm not keen on them.
thanks for any input.
I've got it and have had no problems. Wet UFH, between joists, set on kingspan in a screed. My only slight problem is there is a slight air gap between the screed and the boards in the en suite, so doesn't get as warm as I'd like... but all in all saves the need for unsightly rads.
No problems at all in the bedroom or landing
No problems at all in the bedroom or landing
After much reading last night it sounds like spreader plates are good if weight of screed is a concern. They sound slightly harder to work with - maybe more skill than pure labour involved with the screed.
We're thinking of a ground source heat pump in next few years and it sounds like UFH would integrate better with this - or we'd need massive radiators.
Any thoughts on solid vs engineered flooring. I was reading that some solid wood just isn't recommended with UFH as it will move too much. Very hard flooring like maple seems ok.
We're thinking of a ground source heat pump in next few years and it sounds like UFH would integrate better with this - or we'd need massive radiators.
Any thoughts on solid vs engineered flooring. I was reading that some solid wood just isn't recommended with UFH as it will move too much. Very hard flooring like maple seems ok.
Thinking of doing this myself as I hate the size of the rads in the lounge. I'm putting underfloor in the extension that I'm currently building (within a raised floor). Was talking to some manufacturers at a recent trade show and the spreader plates are the way to go rather than screed. Batten beneath joists, lay Kingspan or similar, foam the gaps and place spreaders on top.
As already said check the condition of joists etc once exposed and I'd use an engineered floor rather than solid timber as it should be more stable (make sure you have it in the house at room temp for a few weeks before laying)
As already said check the condition of joists etc once exposed and I'd use an engineered floor rather than solid timber as it should be more stable (make sure you have it in the house at room temp for a few weeks before laying)
We have suspended wet UFH over the full ground floor living areas of our house in 5 independently controllable zones. It's from www.wundafloor.co.uk and is laid on kingspan with screed on top then the thinest caberfloor and 10mm engineered oak on that.
It works very well although struggled to get warm enough when it was -14 outside as at the moment we have no additional source of heat (might fit a log burner over the summer for the really cold times)
We have it on 24/7 with the thermostats set to 16 overnight and 21 from about 3pm until 10pm as it is slow to react but you get used to it. The house is lovely and cosy all the time with no hot/cold spots or drafts. The first indications on bills are that it's costing similar to our last house but much more comfortable.
We do have up to date insulation everywhere though as it was a full renovation.
It works very well although struggled to get warm enough when it was -14 outside as at the moment we have no additional source of heat (might fit a log burner over the summer for the really cold times)
We have it on 24/7 with the thermostats set to 16 overnight and 21 from about 3pm until 10pm as it is slow to react but you get used to it. The house is lovely and cosy all the time with no hot/cold spots or drafts. The first indications on bills are that it's costing similar to our last house but much more comfortable.
We do have up to date insulation everywhere though as it was a full renovation.
stu67 said:
Was talking to some manufacturers at a recent trade show and the spreader plates are the way to go rather than screed. Batten beneath joists, lay Kingspan or similar, foam the gaps and place spreaders on top.
Depends on whom you speak to - the OP mentioned GSHP, and screed is most definitely the way forward for those systems, whereas it matters less if you're on gas or the like.OP - there's the alternative of Timoleon or Thermaboard if you want to lay quickly on top of the joists instead of between, though again without the screed these are good but less efficient.
RE wood floors, avoid proper boards like the plague - they will twist, bend, crack, and even if none of those, they will move and click and creak all day bloody long. Over and above that, they're an insulator, so they will make the whole system vastly less efficient - either the boiler will have to work a whole hell of a lot harder to pump out the requisite amount of heat (hence expensive and pointless) or you run it a normal level and simply don't get the heat you want / need.
Any barrier between UFH and the room should be of minimal insulation value - hence why tile is recommended as it adds to the thermal mass of the system. Engineered wood is pre-dried and thinner than normal boards so insulate but not as much, and wood boards plus carpet is tantamount to thermal suicide (though it can be done with a correctly specced system, but even then will be far less efficient).
Excellent information, many thanks. Is it the case that screed is better with GSHP as it will retain heat more effectively at a lower temperature?
Joist are 5 and 6" but have been mauled over the years by plumbers and electricians, I am a bit worried about weight of the screed and was leaning towards the spreader plates.
Joist are 5 and 6" but have been mauled over the years by plumbers and electricians, I am a bit worried about weight of the screed and was leaning towards the spreader plates.
The general rule with underfloor heating is the bigger the thermal mass the better.
Small or no thermal mass really rules out an air sourced heat pump, which offer the best value in terms of energy efficiency.
However ground source heat pumps are fine with little thermal mass - as Red Leceister says with UFH heating minimise insulation on the floor itself.
With conventional heat sources the temperature of water going through the floor must be controlled (maximum for concrete is 45 degrees). One big advantage with a heat pump is the low temperatures involved, you NEVER take water up to high temps with a heat pump only to cool it back down, typically the maximum temp of the water going in is 35.
Small or no thermal mass really rules out an air sourced heat pump, which offer the best value in terms of energy efficiency.
However ground source heat pumps are fine with little thermal mass - as Red Leceister says with UFH heating minimise insulation on the floor itself.
With conventional heat sources the temperature of water going through the floor must be controlled (maximum for concrete is 45 degrees). One big advantage with a heat pump is the low temperatures involved, you NEVER take water up to high temps with a heat pump only to cool it back down, typically the maximum temp of the water going in is 35.
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