SoliD Posted February 14 Share Posted February 14 Hi, First post, but hopefully i'll be back for more having discovered this forum. I've got a 1969 built Detached house, ground floor is standard of it's age cavity which has been filled at some point (looked to be in ok shape when I had some doors replaced, and first floor is tile hung single skin. About 2 years ago I started the process of IWI of the first floor with battens and 50mm celotex, which has massively improved the comfort of the floor, but now the ground floor needs some attention as it's generally quite cold, although this isn't helped by the 9x3.5m kitchen/diner only having one double radiator as it's heat source... I have a suspended timber floor with typical 400mm joists, and below this about 30cm or so of space. My plan is to get the floorboards up and in the lounge and hallway insert 100mm PIR between the joists, tape everything up then relay floorboards or lay osb/chipboard depending upon the survival rate, and then in my kitchen/dining room I plan to add a wet UFH heating system to replace the lonely radiator. This will be 25mm dry screed between the joists, then 100mm PIR which i would batten the joists and then support from underneath, and then reading around adding another 100 or 150mm of EPS70 to the bottom of the PIR. Just wondering if i've missed anything or if I could possibly save some money doing similar another way. Link to comment Share on other sites More sharing options...
Super_Paulie Posted February 14 Share Posted February 14 as long as the EPS70 doesnt enclose in the bottom of the joists it'll be ok. The bottoms need to be left exposed to the air under there. See attached for what i have done in my own in terms of insulation, the lower 50mm is held on nails and the whole lot foamed and taped in. So long as your UFH system and design is sound, i dont see any real issues. JohnMo and Nick on here will be along soon im imagine, i got most of my top quality info from them in terms of buffer tanks etc. Link to comment Share on other sites More sharing options...
SoliD Posted February 14 Author Share Posted February 14 (edited) yep, will be attached to the pir with joists free to breathe, did think about cross laying it and leaving occasional air gaps, but then crossed that off the list as a stupid idea, although not quite thought of how to attach it to the PIR yet, could I use some sort of grab adhesive like sticks like s***. Up until yesterday it was just going to be 100mm PIR, until I read more and more about the importance of the insulation under UFH. Would it be worth adding EPS to the non UFH sections too as the cost uplift isn't huge and if i'm under there may as well get it done. Edited February 14 by SoliD Link to comment Share on other sites More sharing options...
Super_Paulie Posted February 14 Share Posted February 14 i have my lower PIR attached by using clout nails into the battens and then pushing the 50mm into those nails so its held in that way, then foamed and taped. Then the 120mm over the top, staggering the joins and again foamed and taped. Yeah, the more insulation the better as far as im concerned, i have mine over the entire ground floor no matter if it has UFH over it or not, such as under the kitchen and island units. Link to comment Share on other sites More sharing options...
SoliD Posted February 15 Author Share Posted February 15 Cool thanks, kitchen will be fun as units will obviously have to stay in place so a lot of crawling about... Link to comment Share on other sites More sharing options...
Super_Paulie Posted February 15 Share Posted February 15 @JohnMo is really clued up on this and might be able to advise you further. Link to comment Share on other sites More sharing options...
JohnMo Posted February 15 Share Posted February 15 Main things I would think about Good insulation as the air below the floor is much colder than soil so losses downwards can be quite big. Especially if you heed the next thing The other is keeping the upward thermal resistance low. Otherwise the flow temperature though the loops can be very high to get through. Another way to do the insulation is use a breather membrane and allow to droop between joists then add mineral wool. Can see two clear advantages, airtightness and getting a good smug fit of the insulation first time. 19 hours ago, SoliD said: wet UFH heating system to replace the lonely radiator. Then just replace the floor boards and utilise your existing radiator or replace with a designer one. Way cheaper to run, system inertia matches the rest of the system. No additional pump to run, home to find for a manifold. Link to comment Share on other sites More sharing options...
Super_Paulie Posted February 15 Share Posted February 15 my "backup" radiators are the classical style i guess you'd call them, raw triple column and the heat they give out and retain compared to your standard radiator (that i have elsewhere) is unreal. They stay warm for hours afterwards when the others are stone cold. 29 minutes ago, JohnMo said: The other is keeping the upward thermal resistance low. Otherwise the flow temperature though the loops can be very high to get through. I have 22mm chipboard in mine which leaves me nervous for when i finally get round to commissioning it. If i could go back id defo get 18mm or a cement board of sorts but im all in now with the chipboard. Link to comment Share on other sites More sharing options...
SoliD Posted February 15 Author Share Posted February 15 Thanks. sorry the lonely radiator is not capable of putting out enough heat for the kitchen and dining room no matter how much it's insulated, it's a 9m long space... well planned by the previous owners. Despite putting a larger double rad which is 1.5m long from memory. There is no space in the kitchen area which is 6m of this length to put a rad as it's all cupboards, hence the move to UFH. Will ensure to minimise the resistance upwards, would be looking 18mm osb/chipboard with lvt on top, so minimal TOG rating. Link to comment Share on other sites More sharing options...
Super_Paulie Posted February 15 Share Posted February 15 i have 2 large rads and 2 plinth heaters in my large space (70sqm) as a backup for the UFH. Those plinth heaters really chuck out some heat, might be worth looking at if you have a lot of kitchen units. Link to comment Share on other sites More sharing options...
SoliD Posted February 27 Author Share Posted February 27 (edited) Started getting the floor up in the lounge. The concrete base here is no way near as deep as where I measured in the understairs cupboard, so i've got about 170mm under the joists to play with. Will get this tidied up and make a start on this half of the room tonight with some luck (depending upon how helpful the wife is with the clearing up ) Edited February 27 by SoliD Link to comment Share on other sites More sharing options...
joe90 Posted February 27 Share Posted February 27 Will you need UFH with all that insulation? Whilst the floor is up you could double the size of that radiator easily (cheaply) and/or run pipes to fit a plinth heater in your kitchen. As @JohnMo says UFH requires way more kit to be installed. Link to comment Share on other sites More sharing options...
SoliD Posted February 27 Author Share Posted February 27 (edited) This is the lounge, not putting in UFH here. UFH is only going in the kitchen room, am considering plinth heaters, but had them before and as nice as the blowing warm air is, there is the additional comfort element that UFH provides. Edited February 27 by SoliD 1 Link to comment Share on other sites More sharing options...
SoliD Posted March 4 Author Share Posted March 4 got half the lounge done and back together now, measuring 1c warmer on the insulated sides carpet currently, now to crack on and do the other half. Bit faffy, but unfortunately limited on space to move furniture due to a 3 month old puppy, although her barking at me sat on the joists was pretty funny , looked at the taped up celotex with quite a lot of scepticism Link to comment Share on other sites More sharing options...
SoliD Posted March 18 Author Share Posted March 18 Lounge all done, got quicker on the second half in terms of time taken, had a couple of iffy celotex cuts, which at the end of a day annoys the hell out of you with ropey joist widths Just need to put some foam in a couple of plug and light sockets and room to go back to normal. Started pulling up a couple of laminate boards in the hallway now, looks like owners have boarded this when they had it done, so hopefully be a lot quicker than taking up and putting the floorboards back in the lounge. Will see how the room feels in the next few days, but with some of the knot holes in the floorboards, it's not hard to see why the room leaked heat on a windy day. Link to comment Share on other sites More sharing options...
SoliD Posted May 10 Author Share Posted May 10 Slow progress but have now done the downstairs toilet, which is a small extension, this had a concrete base and then a 100mm frame chucked on top of it, so I ripped this all out and just filled with Celotex and plugged up the airbrick whilst I was at it which when clearing out could feel the cavity insulation, not sure if it's failed or just wasnt ever put in properly but have capped this off to remove the draft through the cavity. Also completed the hallway which was easier said than done with a 5 month old puppy who seems to love grabbing the foil tape and pulling it apart every time I went out to cut a new slab of celotex... Got a few little bits around the stairs and in the understairs cupboard, but now to move onto the kitchen/diner which will be more complex with the addition of UFH at the same time, but hopefully dealing with the awkward areas first should put me in good stead for this bit. Link to comment Share on other sites More sharing options...
CAJ Posted June 4 Share Posted June 4 Hello, have you considered using wool type insulation? Since it is squishy is can ease the installation to create an airtight and insulated barrier. Have you progressed the other rooms? This step by step guide may be of use: https://www.insulationadvice.co.uk/ia-floor-insulation Link to comment Share on other sites More sharing options...
SoliD Posted June 10 Author Share Posted June 10 I hadn't CAJ, Celotex is so easy to cut to size and much easier to store for me outside as I do the rooms. Especially with the 100mm version as even with the joists being far from straight I can get them in and fill as necessary with foam if required and then tape straight up. Hallway is complete now and even managed to get into the troublesome crawlspace below the stairs (2ft high....) Which took far longer than expected, taking the floorboards out of here was fun :D, but i've also been tarting it up into a hideaway for our Puppy. Few weeks break now until back from Holiday and then will get cracking with the kitchen/dining room, which should be more straight forward being square open spaces. VID_20240608_111023645.mp4 Link to comment Share on other sites More sharing options...
JohnnyC Posted August 6 Share Posted August 6 Hello, Thanks for sharing this. I am considering doing something similar in my ground floor. Quick question about the battens. Did you use treated or untreated ones? Thanks in advance! Link to comment Share on other sites More sharing options...
marshian Posted August 16 Share Posted August 16 On 06/08/2024 at 15:22, JohnnyC said: Hello, Thanks for sharing this. I am considering doing something similar in my ground floor. Quick question about the battens. Did you use treated or untreated ones? Thanks in advance! I did very similar and I used treated tile batten to hold the PIR up (I did all my insulation from below the suspended floors as I have a 2-3 ft crawl space. Link to comment Share on other sites More sharing options...
SoliD Posted August 30 Author Share Posted August 30 in the end i didn't use many battens as I got the PIR super tight, and I had the brick suspending ghost walls for the joists that a lot of it sat on at one end. in the hallway I just filled it full with a layer of polystyrene and then PIR on top. (bar gaps for joist ventilation) Way OTT, but wanted to make sure it'd work and also meant I could walk on it without having to worry about slipping off a joist and pushing a piece of PIR Down Link to comment Share on other sites More sharing options...
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