UFH on the first floor of a Timber Frame

[puntloos]

Timber frame being as it is (a bit more 'moveable') our Architect noted it's typically problematic to have first+ floor underfloor heating since movement can break pipes etc. 

 

 

Has anyone tried UFH on timberframe? Bad idea? Can be done?

Edited September 5, 2019 by puntloos

[Onoff]

@ProDave has done it successfully on the 1st floor I think using a biscuit mix.

[Onoff]

@Nickfromwales will probably be along shortly advocating aluminium spreaders.

 

 

[ProDave]

Your architect is talking b*******s.  If your timber frame moved enough to "break pipes" I would be VERY worried in his design ability.

 

There are 2 ways to do it, either using aluminium spreader plates, or as we did in our previous house, using a biscuit mix as the heat spreader, but that option needs the joists sized for the extra dead load at design stage.

 

Our present house has UFH on a suspended timber floor downstairs (biscuit mix) and just the bathrooms upstairs (spreader platess)

 

UFH is usually Pex Al Pex semi flexible pipe or similar, so it can take a good deal of movement without worry.  If your frame is going to move like your architect thinks, I would worry about all the normal plumbing which in our house is copper, mostly soldered.

[redtop]

UFH is very very common for timber frame houses; however you do it architect is talking nonsense

[Ralph]

17 minutes ago, puntloos said:

Timber frame being as it is (a bit more 'moveable') our Architect noted it's typically problematic to have first+ floor underfloor heating since movement can break pipes etc. 

 

 

Has anyone tried UFH on timberframe? Bad idea? Can be done?

We went back on forth on this. The 3 installers I've spoken to tell me that most people avoid it because the hassle and cost factor when compared to a few radiators is not really worth it, especially if you are fitting any carpets upstairs. I have been told by one person who had it fitted that they get pops and squeaks from the joists but breaking pipes seems like a stretch.

[Bitpipe]

@HerbJ has UFH upstairs in his MBC build - used a low bore pipe in a floor panel that sits on top of the structural OSB IIRC. 

 

I have a timber ground floor over the basement, steel web and pozi joists with 18mm OSB on top and bog standard UFH in spreader plates under that. The water temp is only 30-40 odd degrees so no idea where he gets that concept from.

 

[puntloos]

It's quite possible I misunderstood. Let me inquire. Are there any major downsides conceivable then? I mean, speccing joists for some extra weight might add cost but surely not dramatic - a few %?

[dpmiller]

I've just poured thinscreed over a FF pipe loop on our build, I've put UFH in the bathroom and ensuite  for comfort but the loop also covers the open plan landing/balcony.

 

[Redoctober]

@puntloos have a look at this blog entry - might help explain a few pros and cons. 

 

[Ferdinand]

4 hours ago, puntloos said:

Timber frame being as it is (a bit more 'moveable') our Architect noted it's typically problematic to have first+ floor underfloor heating since movement can break pipes etc. 

 

 

Better move all those bathrooms and loos downstairs...

[joth]

3 hours ago, puntloos said:

It's quite possible I misunderstood. Let me inquire. Are there any major downsides conceivable then? I mean, speccing joists for some extra weight might add cost but surely not dramatic - a few %?

 

Thinking out loud, they might have been referring to the UFH actually causing the movement which might result in some creaking, rather than breaking. I imagine this would be more likely if you have a higher heat output, meaning stuff near the UFH pipes will heat quicker than stuff further away and the whole lot creak a bit as it takes up the difference in these rates.

Pondering further... it is plausible some folks might have some expectation they can mostly leave upstairs heating 'off' but give it a high temp blast before bed time or first thing in morning.  Generally in a well insulated home you'd not going to want to use it that way at all. On this basis, UFH actually makes more sense than radiators, as the latter really have to be used on a high temperature, and all the higher temperature flow pipes (especially if un-lagged) leading to the radiators are a bugger for causing joist creaking even in a traditional built house (come over to our current house if you want a demo).

 

[/speculation]

 

 

 

Edited September 5, 2019 by joth

[ProDave]

No problems with creaks or groans from a timber frame or the plumbing.

 

UFH works best at a low temperature for a long time, rather than a high temperature for a short time.

[HerbJ]

17 hours ago, Bitpipe said:

@HerbJ has UFH upstairs in his MBC build - used a low bore pipe in a floor panel that sits on top of the structural OSB IIRC. 

 

Yes, that's correct.  We installed a Jupiter Proprietary installation system - see  attached. the ECO-100 PI in the bedrooms with engineered wood floors and the ECO-400 PI in the bathrooms with porcelain tiled floors. It was a relatively expensive option, but the Jupiter system also give some measure of acoustic properties as well,. SWSBO wanted comfort and  we both believed that the type of house we built (320m2 in a high value residential area) required UFH on the 1st Floor  if we ever decide to sell. It does provide a added measure of comfort, though for most of the time  with individual room temperature control, which for the most part is set to provide heat to the Master Bed and ensuite, unless we have visitors (family, grandkids...).  l believe there are other BH who decided against fitting upstairs UFH, even if it was only bathrooms, and wish they could revisit that decision!  We have experienced no creaks and groans.  It operates at a very low temperature .

 

We didn't fit any kind of heating on the 2nd Floor but did install plumbing for future installation of heating. We have the study and a play room/media room on the 2nd floor and it the temperature is acceptable in winter. 

ECO-10U Pt E.pdf ECO-40U Pt E.pdf

[Temp]

The key feature of that system is that the UFH system is on top of the structural floor deck. So important to set joists 50mm lower than would otherwise. Especially important if using a mix of different systems in the house.

 

 

 

 

 

 

[Dan F]

@HerbJ Do you have any stats on how often UFH upstairs actually turns on in your case?

 

We are currently specify heating for a 300mm MBC system build. Our current thinking (advice we've been given by consultant) is to only use UFH downstairs and use MVHR post-heater for heating/cooling upstairs as a way of mitigate the concerns with heating/cooling having to propagate from downstairs->upstairs.  We haven't compared costs of UFH vs. post-heater yet though.  Post-heater would be powered by same heat-pump as downstairs UFH.

[Jeremy Harris]

We have no heating at all upstairs, other than heated towel rails in the bathrooms (our house is also an MBC build).  As risk mitigation I included switched fused outlets in the bedrooms, so that I could add small electric panel heaters to the walls if needed.  We have found that we just don't need any heat in the bedrooms at all, only cooling.  We like the bedrooms to be no warmer than about 19°C to 20°C, and even in really cold weather they don't drop below about 19°C.  The only thing I wish I'd done differently is to fit UFH in the bathrooms, as the travertine floors do feel a little bit chilly at times.  I don't think I'd have bothered to fit wet UFH in them though, as for just taking the chill off morning and evening electric UFH switched by the same time switch that controls the towel rails would be fine.  I doubt it needs more than a few tens of watts to take the chill off those floors.

[Bitpipe]

16 minutes ago, JSHarris said:

We have no heating at all upstairs, other than heated towel rails in the bathrooms (our house is also an MBC build).  As risk mitigation I included switched fused outlets in the bedrooms, so that I could add small electric panel heaters to the walls if needed.  We have found that we just don't need any heat in the bedrooms at all, only cooling.  We like the bedrooms to be no warmer than about 19°C to 20°C, and even in really cold weather they don't drop below about 19°C.  The only thing I wish I'd done differently is to fit UFH in the bathrooms, as the travertine floors do feel a little bit chilly at times.  I don't think I'd have bothered to fit wet UFH in them though, as for just taking the chill off morning and evening electric UFH switched by the same time switch that controls the towel rails would be fine.  I doubt it needs more than a few tens of watts to take the chill off those floors.

 

Same as Jeremy and we did go for electric UFH in the tiled bathrooms - was a very last min decision but was cheap as chips and makes quite a difference.

[HerbJ]

On 06/09/2019 at 16:33, Dan Feist said:

@HerbJ Do you have any stats on how often UFH upstairs actually turns on in your case?

 

To be honest, I have no hard data but SWMBO does prefer the main bedroom/ensuite to be warm, so I imagine the UFH in these rooms  is active for a  fair % of time when the weather is really cold.

We do have the advantage that 1st Floor every bedroom, the main ensuite and the family bathroom have individual temperature sensors and are controlled to suit. Most of the time,  everywhere except the  main bed/ensuite is set so that they never come on and they sit happily at 18 to 20C, a couple of degrees below the Ground Floor. 

[Moonshine]

I am bringing this thread back, as I am wondering about using a wet underfloor heating system in first floor bathrooms, and radiators in bedrooms.

 

For this i am thinking of having a UFH circuit for the upstairs bathrooms which will have hard floors, but using aluminium spreader plates screwed to the underside of the chipboard floor (between i-joists).

 

The heat source will be from a ASHP so won't be really hot, so i presume i need to put some insulation in the joists underneath so it radiates upwards. How much insulation is typical in this type of installation?

[Bitpipe]

I went with an electric mat in each bathroom and it works just fine - a 150W system is adequate, sits on 6mm insulated backer board, covered in latex with porcelain tiles above. Total build up is 25mm. We also have wet towel rads.

 

We have wet low temp UFH on ground floor on spreader plates (our GF is suspended timber over basement which itself has no heating) and there is only rockwool under the plates, installed when basement ceiling was being boarded. Even at 35^o  the heat easily penetrates 18mm OSB, 21mm of ply and the 8mm of resin floor.