September 11, 20215 yr Evenin’ all! The plan is to fit UFH in 2 downstairs carpeted rooms, the floor will be - 100mm pir (max we can get whilst maintaining 50mm air gap) between joists - 18mm chipboard - 20mm foiled eps with UFH pipes routed in - ??? - underlay (0.7 - 1tog) - carpet (1 - 1.5tog) the question is what (if anything) needs to go in between the eps and the underlay? Thanks!
September 11, 20215 yr Wouldn't you put routed chipboard on top of the EPS? Then underlay and carpet atop the chipboard?
September 11, 20215 yr Author 32 minutes ago, Onoff said: Wouldn't you put routed chipboard on top of the EPS? Then underlay and carpet atop the chipboard? Didn’t know such a thing existed! yup will do that. Do the ‘empty’ bits of routed chipboard need filling with anything? Or would you feel the uneven surface of chipboard and pipes through the carpet and underlay? I guess you could always also use pir over joists for better results then the eps? Or are either not strong enough to take the further floor make up? Edited September 11, 20215 yr by CotswoldDoItUpper
September 11, 20215 yr I'm a bit lost as to where the 50mm air gap is? Is this a suspended timber floor? How deep are the existing joists? Cleverer people will be along shortly. Just Google "routed chipboard UFH" and go Images. Use btw 22mm boards not 18mm. Putting underlay then carpet direct onto foiled EPS is a bad idea btw. Edited September 11, 20215 yr by Onoff
September 12, 20215 yr Author 12 hours ago, Onoff said: I'm a bit lost as to where the 50mm air gap is? Is this a suspended timber floor? How deep are the existing joists? Cleverer people will be along shortly. Just Google "routed chipboard UFH" and go Images. Use btw 22mm boards not 18mm. Putting underlay then carpet direct onto foiled EPS is a bad idea btw. - air gap under joists (yes suspended floor) - joist depth 100mm on 400 centres - I wasn’t planning on putting underlay directly onto the eps, Im trying to establish what I should put between them. google images here I come!
September 12, 20215 yr Author Any idea what should go between UFH pipes and carpet underlay? surely if you lay routed chipboard there will still have to be a covering so you can’t feel the empty bits where there are no pipes?
September 12, 20215 yr I think you have two options something like.. Carpet Underlay 18mm OSB or Flooring grade chipboard Routed and foiled EPS with UFH pipe between joists Insulation between joists Carpet Underlay Metal Heat spreader plates (just flat sheets) Routed Chipboard and UFH pipe 18mm OSB or Flooring grade chipboard Insulation between joists I don't think 18mm Routed Chipboard is strong enough on its own over joists. I believe its intended for use over concrete floors or similar. Edited September 12, 20215 yr by Temp
September 12, 20215 yr It can be a pig to get pir to fit tightly between floor joists. Some people cut them boards 5-10mm short on the width then fill with expanding foam. An option is using mineral wool instead. @Ferdinand did similar I think with his Little Brown Bungalow refit? A few pointers here. https://www.ecologicalbuildingsystems.com/post/best-practice-approach-insulating-suspended-timber-floors Whatever you decide or get told, post up here. Someone will have seen it before and likewise comment as to good/bad.
September 13, 20215 yr Routed chipboard should be strong enough for joisted floor providing the routed grooves are laid perpendicular to the direction of the joists. A 3mm ply or even 1.5mm aluminium sheet on top of groved chipboard would be sufficient to prevent feeling the empty grooves. Or just fill the grooves that don't have pipe in with an adhesive, but most grooves will have pipe and this should be flush with the top of the chipboard and won't be felt though the carpet and underlay. Take care on the thermal resistance of your carpet. Kind of goes without saying but a carpet will hold the heat back.
September 13, 20215 yr LBB th 14 hours ago, Onoff said: It can be a pig to get pir to fit tightly between floor joists. Some people cut them boards 5-10mm short on the width then fill with expanding foam. An option is using mineral wool instead. @Ferdinand did similar I think with his Little Brown Bungalow refit? Thread: The detail I used for my existing suspended floors. Note this is wall rads not ufh. For UFH I would want more insulation - probably 75mm not 25mm PIR over the floor. Given that my final restriction was being able to trim internal doors enough (limit was about 60mm), I might be forced to go PIR between the joists if I was not able to do things to doorframes. Calculate the u-values. The other option is to seal the void to moisture and fill it with polystyrene beads. May cause BCO to have kittens. Calculate your u-values against what you need. Further discussion on this Boffin's Corner thread about the build up: Ferdinand
September 13, 20215 yr @CotswoldDoItUpper I'm in the process of installing UFH to the first floor in my home which will predominantly have carpet on top. I came across this underlay which may also be of use to yourself, https://wilsons-underlays.co.uk/thermalstream.html Edited September 13, 20215 yr by vala
September 13, 20215 yr Author 3 hours ago, vala said: @CotswoldDoItUpper I'm in the process of installing UFH to the first floor in my home which will predominantly have carpet on top. I came across this underlay which may also be of use to yourself, https://wilsons-underlays.co.uk/thermalstream.html That’s a great suggestion thanks! Did you install anything between the pipes abs the underlay to ‘level’ the floor, and if not, can you feel the pipes through it?
September 13, 20215 yr 27 minutes ago, CotswoldDoItUpper said: That’s a great suggestion thanks! Did you install anything between the pipes abs the underlay to ‘level’ the floor, and if not, can you feel the pipes through it? I'm having a different system to yourself. I'm going for a pug screed system, so on top of my joist at present I'll have chipboard T&G boards first, then the underlay, then carpet. However I've asked my structural engineer if I could use cement T&G boards as these should make the system more efficient. However they are much heavier. I'm a good 1-2 months away from potentially evening running the system....still doing the prep work!!
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