Upper/Suspended Floor - UFH Options

[Barney12]

There have been some good topics over on eBuild and here http://forum.buildhub.org.uk/ipb/topic/533-ufh-in-passive-house-build/?page=1

regarding the need for UFH upstairs in a house built to passive standards.

 

We've decided we will fit an UFH circuit upstairs. Mainly as we're intending to have no carpets and don't want cold feet!

 

We're hopefully going for an MBC build and thus construction will be webbed joists with 22mm Chipboard Decking.

 

I've seen a couple of posts that suggest people have fitted their UFH from underneath? On paper that sounds like a right ball ache?

Or do MBC loose lay the floor to allow lifting and adding of spreader plates and pipes?

 

Or.....the quote states the floor is capable of taking a 50mm screed so is putting the UFH runs on the 22mm floor and screeding an option? (I'd need to satisfy myself of ceiling heights).

 

Just trying to get the order of events right in my head!

 

TIA!

[AliG]

I have UFH in screed and in spreader plates. The spreader plates are considerably inferior in terms of providing a nice stable temperature. In fairness my current house needs more heat input and I don't believe that the spreader plates cannot supply as much heat per square metre as a screed floor.

 

I almost used posi joists. If I had, I would have put UFH in screed on it as it will also give a more solid floor and better sound deadening.

 

From the people with MBC houses on the site it seems they are extremely well insulated. If your aim is to have warm floors you may be disappointed as the heating may come on so rarely and use such a low flow temperature that you might not actually have a warm floor. I am in the same position in my new place. I wonder if it is a waste but am putting it in just in case, although we then have a top floor games room and I am not putting UFH in there. However, depending on the spec I believe the insulation in an MBC house will make it pretty much redundant.

 

Maybe the MBC owners can comment.

 

 

 

 

[dogman]

We are currently living in a very well insulated SIP house while our MBC (300mm twin wall) house is built. So far we have not turned on the underfloor heating upstairs and downstairs it is limited to the living room and a bathroom for about an hour in the evening.

I find the MHVR evens the temperature out around the house.

 

The new house will have underfloor in the slab downstairs but upstairs will be fan coil radiators.

 

An airsource heat pump that modulates will be the heating source

 

My hope is that if we find the house gets warm in the summer they can be used to cool the bedrooms and the slab downstairs.

 

[Russdl]

Similar position to Barney.

 

As it stands I'm considering electric UFH for the upstairs bathrooms, but that is from a position of limited information and best guess. I would appreciate any feedback from a 'passive house' dweller with a similar set-up.

[jack]

As I've posted before, we have an MBC house and have found our upstairs bathrooms to be undesirably cold in winter. Tiles just feel cooler than they actually are due to the way they suck heat from your feet.

 

We actually had MBC install the bathroom floors in our house 50mm lower than the rest of the upstairs floors, to leave space for underfloor heating. In the end we decided not to go for it, and it's one of the choices I regret.

 

We're going to look into infrared heating panels. I wonder whether having one of these come on for a few mins in the morning before we wake up will take the chill out of the air (and off the tiles) to make the bathrooms a bit more comfortable first thing.

[joe90]

1 hour ago, jack said:

As I've posted before, we have an MBC house and have found our upstairs bathrooms to be undesirably cold in winter. Tiles just feel cooler than they actually are due to the way they suck heat from your feet.

 

We actually had MBC install the bathroom floors in our house 50mm lower than the rest of the upstairs floors, to leave space for underfloor heating. In the end we decided not to go for it, and it's one of the choices I regret.

 

We're going to look into infrared heating panels. I wonder whether having one of these come on for a few mins in the morning before we wake up will take the chill out of the air (and off the tiles) to make the bathrooms a bit more comfortable first thing.

It's because of your comment Jack that I am going to put electric UFH in our on suite but like you I find tiles cold to the feet so we are going with vinyl. As far as know infared heaters only heat people, not " things " ( I stand to be corrected ?)

Edited October 27, 2016 by joe90

[dogman]

We have electric underfloor in the en suite wet room to dry the floor and it provides plenty of warmth for your feet

Don't need to worry about floor level as it sits under the tile in the adhesive

It responds quicker and is probably cheaper to run when heating one room   ( I also stand to be corrected ?)

 

[jack]

9 hours ago, joe90 said:

It's because of your comment Jack that I am going to put electric UFH in our on suite but like you I find tiles cold to the feet so we are going with vinyl. As far as know infared heaters only heat people, not " things " ( I stand to be corrected ?)

 

I think it's more accurate to say that they heat "things" rather than "air".  

 

Knowing what I know now, I think we'd have gone for electric UFH.  I suspect you only need it on for a short period to take the chill off.  

[Barney12]

On 26/10/2016 at 12:38, Barney12 said:

There have been some good topics over on eBuild and here http://forum.buildhub.org.uk/ipb/topic/533-ufh-in-passive-house-build/?page=1

regarding the need for UFH upstairs in a house built to passive standards.

 

We've decided we will fit an UFH circuit upstairs. Mainly as we're intending to have no carpets and don't want cold feet!

 

We're hopefully going for an MBC build and thus construction will be webbed joists with 22mm Chipboard Decking.

 

I've seen a couple of posts that suggest people have fitted their UFH from underneath? On paper that sounds like a right ball ache?

Or do MBC loose lay the floor to allow lifting and adding of spreader plates and pipes?

 

Or.....the quote states the floor is capable of taking a 50mm screed so is putting the UFH runs on the 22mm floor and screeding an option? (I'd need to satisfy myself of ceiling heights).

 

Just trying to get the order of events right in my head!

 

TIA!

 

I knew this thread would turn into another debate about IF we should fit UFH upstairs  

but we ARE going to and will just take the risk that it might not get switched on but I'm pretty confident it will, we are in a high and exposed position and we get some pretty grim weather!

 

SO.............

 

How to fit as per my OP?

[Roundtuit]

We are (or maybe were...) planning wet ufh in first floor bathrooms for our timber frame (not mbc) and I had a mind to lift the decking chipboard at a later date to do the job. Having seen the decking go down yesterday and today, I reckon fitting from underneath is the easier option. The boards interlock, are glued and nailed, and the first floor walls sit on top of them so fitting loose wasn't an easy option either.  I have no clue how to attempt fitting it from below though...

[Barney12]

11 minutes ago, Roundtuit said:

We are (or maybe were...) planning wet ufh in first floor bathrooms for our timber frame (not mbc) and I had a mind to lift the decking chipboard at a later date to do the job. Having seen the decking go down yesterday and today, I reckon fitting from underneath is the easier option. The boards interlock, are glued and nailed, and the first floor walls sit on top of them so fitting loose wasn't an easy option either.  I have no clue how to attempt fitting it from below though...

 

The point about the internal walls sitting on top wasn't one I had thought of. Bugger  

Perhaps our resident egg spirt @Nickfromwales has got some insight on fitting from underneath?

Edited October 27, 2016 by Barney12

[Nickfromwales]

First and foremost, FIT THE UFH FIRST WHENEVER YOU CAN !

Retrofitting from underneath is simply hard work. @Bitpipe was in the same boat as you, but I managed to nudge him into 'doing the right thing' and he put his plates and pipe in as the build went up. MBC lads joined in and helped ( took over iirc ) to lay it and it saved a LOT of grief. 

The ideal set of events would be to allow for your posi-joists to have an 18mm batten atop, and then plates. The batten is required to allow you to cut the end for the pipe to transverse joist space to joist space as posi-joists can't be cut. Not a problem with regular joists btw. 

The main thing, either way, is to make sure the plates are fixed up nice and snug. I use an air powered stapler to fix them to the underside of the deck material so the heat transfer ( promoted by surface contact ) is as good as it can get. 

The only real tip for fitting from underneath is make sure you have a pipe decoiler, make sure you have at least 3 people on it, and don't be in a rush to do it. Pulling in 100m of pipe is a pain, kinking the last 10m piece and having to pull it all out and start again would be soul destroying. . 

Cut a few short pieces of pipe and get used to the minimum bending radius, ( before the pipe kinks ), by trying to form 180o bends in the sample pieces. That'll give you an insight into how far you can & can't 'push' the pipe. 

[Barney12]

Thanks Nick. Looks like getting them in first is the way to go. Doing from underneathernjust seems like a major ball ache. 

 

OR.....go for the screed option on the first floor.....? 

 

All, Is there any any other advantage to the 50mm first floor screed other than sound deadening (and ease of UFH install)?

Edited October 28, 2016 by Barney12

[Vijay]

Nick, if you can't get an 18mm batten in, what are your options?

[Nickfromwales]

6 hours ago, Vijay said:

Nick, if you can't get an 18mm batten in, what are your options?

Dip under the top rail of the joist. Not ideal, but if you commission ( purge ) properly you should eradicate any air locks / pockets. Once full of water and treated properly with inhibitor ( X100 / similar quality product ) then it should be fine. 

Air vents ( automatic ) on both of the manifold rails is essential. .  

[Bitpipe]

8 hours ago, Nickfromwales said:

First and foremost, FIT THE UFH FIRST WHENEVER YOU CAN !

Retrofitting from underneath is simply hard work. @Bitpipe was in the same boat as you, but I managed to nudge him into 'doing the right thing' and he put his plates and pipe in as the build went up. MBC lads joined in and helped ( took over iirc ) to lay it and it saved a LOT of grief. 

The ideal set of events would be to allow for your posi-joists to have an 18mm batten atop, and then plates. The batten is required to allow you to cut the end for the pipe to transverse joist space to joist space as posi-joists can't be cut. Not a problem with regular joists btw. 

The main thing, either way, is to make sure the plates are fixed up nice and snug. I use an air powered stapler to fix them to the underside of the deck material so the heat transfer ( promoted by surface contact ) is as good as it can get. 

The only real tip for fitting from underneath is make sure you have a pipe decoiler, make sure you have at least 3 people on it, and don't be in a rush to do it. Pulling in 100m of pipe is a pain, kinking the last 10m piece and having to pull it all out and start again would be soul destroying. . 

Cut a few short pieces of pipe and get used to the minimum bending radius, ( before the pipe kinks ), by trying to form 180o bends in the sample pieces. That'll give you an insight into how far you can & can't 'push' the pipe. 

 

100% - we  threw down the UFH in a day and a half over our 100m2 suspended timber ground floor. 

 

As Nick says, I looked into various options but using alu spreaders was the cheapest and the MBC lads were happy to help laying them down ahead of the floor deck - in fact they took over and put the pipe down also - I'm sure you can negotiate the cost of the pipe from MBC (same as you'd use in screed) and the plates are £3-4 each from UFH Superstore or Boulder. A few bacon sandwiches will grease the wheels here

 

100% on the de-coiler too. MBC will have one in the van usually if you don't want to hire or buy (and return if you 'forget' to use it ).

 

Once the pipes were down, the 22mm deck board followed - in our case, rather than use battens we left out sections of deck where the returns came up over the pozi joist tops (held with a pipe clip) - its impossible to thread the pipe through the joist at each return. This was OK for us as we knew we'd be laying ply on top in prep for the resin floor - if you go the same way, allow an extra 12mm floor thickness.

 

Also did the stapling from underneath and everything was snug. Just watch when internal walls are fixed  to the floor and plumbers & sparks drill though the floor - they need to be constantly reminded abut the pipe underneath!

 

We have nearly 50mm floor build up in timber (22mm OSB deck and 21mm in ply) then 2mm rubber crumb and 2mm resin. Takes a while to warm up but has rarely come on so far with the air temp set to 21.

 

We don't have heating upstairs apart from towel rads and electric UFH in the bathrooms (very last min addition)  - spent pennies on the UFH - cheapest 100W/m2 mats from E-bay and they work a treat. Tiler was happy to throw them down as he went but make sure your electrician has made the necessary provision with ducting etc for the probe and tail of the mat.

 

Top tip - label the circuit pairs (and their location) before you commission the heating. We have 6 circuits downstairs, 5 on one stat and one on the other. Took some trial and error to isolate the one circuit - had to crank the heating up and send the cat off to find the warm spot.

 

 

 

[Bitpipe]

42 minutes ago, Nickfromwales said:

Dip under the top rail of the joist. Not ideal, but if you commission ( purge ) properly you should eradicate any air locks / pockets. Once full of water and treated properly with inhibitor ( X100 / similar quality product ) then it should be fine. 

Air vents ( automatic ) on both of the manifold rails is essential. .  

 

We found dipping very tricky and gave up after the first loop. Instead we left out a long slot of deck where the loops crossed over the tops of the joists and then put ply over the top of this. Will see if I can dig out a pic.

 

If Brendan is on your job, he should remember what he did at mine - just remind him about the basement house.

[PeterW]

1 hour ago, Bitpipe said:

We don't have heating upstairs apart from towel rads and electric UFH in the bathrooms (very last min addition)  - spent pennies on the UFH - cheapest 100W/m2 mats from E-bay and they work a treat. Tiler was happy to throw them down as he went but make sure your electrician has made the necessary provision with ducting etc for the probe and tail of the mat.

 

Can you remember which manufacturer / seller the mats were from ..?? Plan to do something similar with the timing controlled from a central point. 

[Bitpipe]

2 hours ago, PeterW said:

 

Can you remember which manufacturer / seller the mats were from ..?? Plan to do something similar with the timing controlled from a central point. 

 

Warmstar - they do a whole kit, primer etc. Tiler really liked their mats as they were properly sticky. I chose the default stat and just binned it, got a decent one from UFH SS. Also got the 6mm insulation boards, latex and tanking from ebay.

 

Would advise getting the digital multimeter and installation alarm as well - it clips on and detects earth and L/N shorts during the install.

 

Take lots of pics when laying, before laytexing etc just in case you need to cut the tiled floor after - my plumbers had to do this to get the waste in for the free standing bath.

 

Was never so happy when they all warmed up for the first time.

[oldkettle]

15 hours ago, Nickfromwales said:

The ideal set of events would be to allow for your posi-joists to have an 18mm batten atop, and then plates.

 

Nick, are you describing the "Diffuser plates on batons" solution as displayed here https://www.underfloorheatingsystems.co.uk/underfloor-heating-design/floor-construction/#! ? Just trying to make sure I get the picture right.

[Frogeye]

I went for the battening the web joist route and got on very well with it. I used a 22mm x 90mm sawn timber (or thereabouts) pasloded and D4 glued on to my webjoists (about 70mm wide), nailed down the spreader plates with some clout nails, threaded in the pipe and then boarded out with 22mm egger chipboard (glued and screwed).

 

Things I learnt as I went - have a decent sized sharpie pen and make notes of where pipes cross over the joists to avoid mindless screwing mistakes, don't weave the the pipe even under one joist (see below) - even on a small ensuite circuit that whole length of pipe then needs to be threaded down that same route.

 

 

I bought an air stapler (on NickfromWales advice/suggestion) only £20 off Amazon and fixed the spreader plates back to the underside of the flooring (done from below) - having an enthuasiatic 15 year old also helped this job go well

 

Another real benefit that helped a lot (I didn't learn this until I made my way downstairs to do the ground floor) is to use a bending spring on the pipe to help with forming corners and tight bends:

http://www.ebay.co.uk/itm/UFH-PROFESSIONAL-UNDERFLOOR-HEATING-AL-PEX-PIPE-SPRING-BENDER-/141260384210?var=&hash=item20e3c667d2:m:mH_qsDtK7756rsBIEu_V3Bw

 

I think I could have lived without a pipe-decoiler, I had 500m coils from Boulder and these were more than it could cope with, just rotating the coil on a clear bit of board seemed to go just as well.

This was one of the more rewarding things I did on the build - good luck!

 

[Barney12]

Thanks @Frogeye excellent info.

[Nickfromwales]

20 hours ago, oldkettle said:

 

Nick, are you describing the "Diffuser plates on batons" solution as displayed here https://www.underfloorheatingsystems.co.uk/underfloor-heating-design/floor-construction/#! ? Just trying to make sure I get the picture right.

This method

That allows you to cross the posi joists without cutting into them. Just remove the batten accordingly. 

[oldkettle]

37 minutes ago, Nickfromwales said:

That allows you to cross the posi joists without cutting into them. Just remove the batten accordingly. 

 

Thank you, I got that.

 

Why is it better than this one? https://www.underfloorheatingsystems.co.uk/wp-content/uploads/2016/04/Diffuser-Plates-above-Floor-with-batons.png ? Looks simpler to implement but clearly there is a catch?

Well, I guess it would not work well (not enough support) for the tiles.

Edited October 29, 2016 by oldkettle

[Nickfromwales]

On 29 October 2016 at 20:22, oldkettle said:

 

Thank you, I got that.

 

Why is it better than this one? https://www.underfloorheatingsystems.co.uk/wp-content/uploads/2016/04/Diffuser-Plates-above-Floor-with-batons.png ? Looks simpler to implement but clearly there is a catch?

Well, I guess it would not work well (not enough support) for the tiles.

That method is for wooden floor as your finished floor. .  The only thing I'd add to that scenario is fitting some fluffy ( Rockwool ) under the plates to make them slightly proud of the finished height. That way, when you fix the wooden floor down you'll be forcing the plates against the fluffy and ensuring good surface contact between the plates and the wooden floor. 

If you look at Frogeyes pics above you'll see how the plates naturally want to sag so that needs addressing with either method, eg fluffy or staples.