North Coast Self Builder Posted February 4 Posted February 4 Hi people I'm looking at the build up of my first floor and looking for the most cost effective solution for an UFH build up? I've pretty much decided on screed but my architect is keen that there is a layer of insulation on top of the chipboard floor to lay the UFH pipes on? I had wondered originally if we could do without an insulation layer altogether. There is acoustic wool between the joists and it is a timber frame house so the overall thermal envelope is secure. Question 1: Do I need an insualtion layer at all or is there an alternative way of laying the piping on to the floor? Question 2: If I need an insulation layer, can I go for the cheapest possible polystyrene insulation sheets. Will that work OK with UFH? Thanks for any help you can give.
Mr Punter Posted February 4 Posted February 4 There is a growing consensus that there is no point in UFH on the first floor, especially if it is just bedrooms & bathrooms. Save yourself some cash. Just towel rads.
Dunc Posted February 4 Posted February 4 Won't the acoustic insulation between the joists be providing sufficient insulation to push most of the heat up in to the upstairs rooms? That's what I'm hoping will happen for me Despite the general consensus on the forum that UFH is not needed upstairs, where people have provided data, there seems to be a 2-3oC drop from downstairs. Most people reporting this seem to have near-passive type houses. Problably fine if you're sleeping, but if you use the rooms during the day (e.g. work from home in an upstairs office, kids play room) maybe not so good? Just my humble opinion. However, that 2-3oC can probably be provided in other ways like towel radiators, panel heaters and the like. I don't have the technical knowledge to do the calculations to know how much heat would be required upstairs, so I'm putting UFH in as it's relatively inexpensive in the grand scheme and not easily retrofitted. Caberdek on joists, plastic sheet (maybe not needed?), UFH pipes clipped down, dry mix sand&cemet ("Pug" mix) surrounding the UFH pipes, between 25 or 30mm battens (depending on UFH pipe diameter and clip size), caberdek on top to support final floor covering. @Redoctober has a very nice blog post on how theirs was done if you can find it. I think this will work out about £1500 cheaper than Lewis metal deck with liqid screed for me, over about 57m2 and seems very DIY-able. If paying a contractor, I'd just do the liquid screed as that will be much quicker. 1
North Coast Self Builder Posted February 4 Author Posted February 4 thanks. i have read this quite widely. I do like a warm house though - 21 / 22 degrees and we have some living and working space on upper floor
North Coast Self Builder Posted February 4 Author Posted February 4 3 minutes ago, Dunc said: Won't the acoustic insulation between the joists be providing sufficient insulation to push most of the heat up in to the upstairs rooms? That's what I'm hoping will happen for me Despite the general consensus on the forum that UFH is not needed upstairs, where people have provided data, there seems to be a 2-3oC drop from downstairs. Most people reporting this seem to have near-passive type houses. Problably fine if you're sleeping, but if you use the rooms during the day (e.g. work from home in an upstairs office, kids play room) maybe not so good? Just my humble opinion. However, that 2-3oC can probably be provided in other ways like towel radiators, panel heaters and the like. I don't have the technical knowledge to do the calculations to know how much heat would be required upstairs, so I'm putting UFH in as it's relatively inexpensive in the grand scheme and not easily retrofitted. Caberdek on joists, plastic sheet (maybe not needed?), UFH pipes clipped down, dry mix sand&cemet ("Pug" mix) surrounding the UFH pipes, between 25 or 30mm battens (depending on UFH pipe diameter and clip size), caberdek on top to support final floor covering. @Redoctober has a very nice blog post on how theirs was done if you can find it. I think this will work out about £1500 cheaper than Lewis metal deck with liqid screed for me, over about 57m2 and seems very DIY-able. If paying a contractor, I'd just do the liquid screed as that will be much quicker. Yes Dunc. I was hoping same re the acoustic insulation. Keen to avoid the circa £2k for 120m2 of 25mm PIR that the architect says in needed.
Nickfromwales Posted February 4 Posted February 4 35 minutes ago, North Coast Self Builder said: Yes Dunc. I was hoping same re the acoustic insulation. Keen to avoid the circa £2k for 120m2 of 25mm PIR that the architect says in needed. Hi. As the 1st floor of the property is within the heated envelope, the insulation your architect suggests is completely unnecessary (redundant). 25mm would do the square root of zilch anyways with UFH, so the subfloor would get heated regardless of it, and I personally think you'd be better off with the thicker screed atop the (22mm?) deck boards. You simply lay the membrane, tape and staple it down as required (do a good job of this), then clip the pipes to the deck with clip rails or simple nail clips, and pour the screed. Prob a good idea to put expansion joints at each doorway / threshold as this will run at a slightly higher temp than is 'ideal', eg so it is responsive and can cope, and will therefore expand and contract a little more than say a slab would; not so important with wood floor, but defo at any transitions (wood meets tiles of a bathroom etc). Without seeing the house or being in possession of any proper details that's the best advice I can give here of course Some pics of a job I did late last year, same situation. You can see the expansion joints in that doorway. Membrane down over the deck, and off to go. Zero issues, but as said will likely be an expensive ornament or used to put a thimble of heat in when ‘cozy’ is required. Work from home family.
Conor Posted February 4 Posted February 4 For some additional context, we ran our first floor UFH pipes across a timber landing due to manifold location. A dozen pipes clipped to the SIDES of the floor joists, before 22mm chipboard, underlay and carpet. Not actual UFH but you can still feel the difference in floor temperature. Insulation definitely not needed. 1
North Coast Self Builder Posted February 4 Author Posted February 4 Thanks Nickfromwales. very helpful reply 1
Redoctober Posted February 5 Posted February 5 17 hours ago, Dunc said: Despite the general consensus on the forum that UFH is not needed upstairs, where people have provided data, there seems to be a 2-3oC drop from downstairs. Most people reporting this seem to have near-passive type houses. Problably fine if you're sleeping, but if you use the rooms during the day (e.g. work from home in an upstairs office, kids play room) maybe not so good? Just my humble opinion. However, that 2-3oC can probably be provided in other ways like towel radiators, panel heaters and the like. I don't have the technical knowledge to do the calculations to know how much heat would be required upstairs, so I'm putting UFH in as it's relatively inexpensive in the grand scheme and not easily retrofitted. This is exactly what drove us to do what we did and also, it is our experience having lived with it for the past 5 years or so. I'm so pleased I went the " extra mile " on this part of our build and put in UFH upstairs. Yes, as always, there are alternative options, but for the reasons stated above by @Dunc I'm more than happy. Not only that, it allowed us the freedom to place furniture etc where we wanted, without having to navigate radiators or panel heaters etc. 1
Dunc Posted February 5 Posted February 5 Useful feedback @Redoctober, thanks! Can I just ask do you have any creaking problems with the upstairs floor? My architect is pushing hard for the Lewis deck & screed which he says would remove such a risk. (apologies to @North Coast Self Builder for hijacking the thread!)
Nickfromwales Posted February 5 Posted February 5 Hijacking is good, fill your boots lol. I’ve done scores and scores of these types of floors, and there’s zero need for the Lewis deck etc, and fyi I like that system a lot, it’s just unnecessary for anything other than the more sizeable dwellings. I was going to spec it for the 2nd floor areas for an 1800m2 property, for eg. Mid-sized you’ll get away with screed over timber deck, just make sure you’re chosen P5 deck boards are D4 glued and fixed VERY well, as the squeaks and creaks come from the fixings, not the wood!!! Not many people know that. 1
Redoctober Posted February 5 Posted February 5 2 hours ago, Dunc said: Useful feedback @Redoctober, thanks! Can I just ask do you have any creaking problems with the upstairs floor? My architect is pushing hard for the Lewis deck & screed which he says would remove such a risk. (apologies to @North Coast Self Builder for hijacking the thread!) No creaking whatsoever coming from the upstairs floor - all nice and solid - Pity I can't say the same about our staircase though. There is an annoying creak on step number 4 - oh well, all part of the fabric of the house🤣 1
Redoctober Posted February 5 Posted February 5 2 hours ago, Nickfromwales said: Just make sure you’re chosen P5 deck boards are D4 glued and fixed VERY well, as the squeaks and creaks come from the fixings, not the wood!!! Not many people know that. Very interesting - didn't know that - every day's a school day👍
Nickfromwales Posted February 5 Posted February 5 1 hour ago, Redoctober said: Very interesting - didn't know that - every day's a school day👍 Yup. The ‘eeek’ sound comes primarily from the deck boards ‘rubbing’ up and down the screw shank or nail. 5x 5.0x50mm screws per joist with a line of D4, and never had a single noise on any of them. Using gas nails is ok, but in the old days when I had to go faster to make money and gas nail them, I made sure I stood with both feet either side of where the nail was going so the board was compressed to the joist before firing. I also made sure to use quality ring shank nails, and put 2 in if I was ever only 95% sure that the first one ‘didn’t feel right’ eg went in too easily.
marshian Posted February 5 Posted February 5 25 minutes ago, Nickfromwales said: Yup. The ‘eeek’ sound comes primarily from the deck boards ‘rubbing’ up and down the screw shank or nail. 5x 5.0x50mm screws per joist with a line of D4, and never had a single noise on any of them. No shank for the boards to rub on - threaded from head to tip 😉
Nickfromwales Posted February 5 Posted February 5 1 minute ago, marshian said: No shank for the boards to rub on - threaded from head to tip 😉 You’ll hate me, I don’t ever use fully threaded screws as I don’t like the way they can ‘jack’ the board up away from the joist . You then have to murder them to get the heads sunk and the board down tight. Yes, I’m an objectionable individual, you’ll get over it 😆
marshian Posted February 5 Posted February 5 3 hours ago, Nickfromwales said: You’ll hate me, I don’t ever use fully threaded screws as I don’t like the way they can ‘jack’ the board up away from the joist . You then have to murder them to get the heads sunk and the board down tight. Never have an issue with that - wind them in and if you feel the board lift - back em out and then bang them in again. 3 hours ago, Nickfromwales said: Yes, I’m an objectionable individual, you’ll get over it 😆 I'm sure I will 1
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