SoliD

Thanks, possibly but another expense I wanted to do without, so far the heat is nice and uniform across the room, even in the kitchen where the pipe and pug mix only run down the centre of the room. I managed to get 150mm PIR all the way under the cupboards with a lot of swearing and sweating....plus a bit of foam spray and gapotape where necessary, don't appear to have any draughts coming through.# yeah it needed to be as the kitchen was staying in place and the room is one long area. It's definitely more work getting all the PIR etc cut, but the pug mix went down in one day and could be lightly walked upon 2 days later (dog obviously had other ideas wandering straight on top of it on the day). Did mean I could save some money reusing floorboards etc as well.

Worst part was putting the floorboards back down, took a long time being extra careful, in hindsight doing it again i'd have ripped out the joists in the non kitchen end.

Bit of a bump but finished this back in December, and got it fired up about a month ago, has been working great so far, seem to be burning the same amount of gas to heat the whole downstairs compared to just the lounge before. Have since had the old 80s double glazing replaced which during the last cold snap showed it didn't need to be on for as long. Eventually ended up using 100mm EPS, and then 150mm PIR leaving 35mm or so gap for the dry screed and pipework. Just wish I'd have put it out in the hallway now

I run our AC all day for 3-4 months a year in the summer and barely notice it as it goes on tickover flow, but this is from the rounded ceiling mounted vents. Most units will come with their own app now negating the need for a separate smart thermostat. Rather than replacing if it still works, maybe get it cleaned up and serviced and see how it performs, a new system pays for a lot of electricity.

Definitely the AC, also should lower humidity as it cycles the air, so will feel warmer in theory.

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

Almost due to start this now, I will be able to lay about 200mm below the screed which would be 60-70mm deep. Now I have quite a bit of 50mm EPS left from my previous purchase for my lounge and hallway but will need to buy more PIR. Should I use the EPS elsewhere in the house (could chuck it all in the loft probably) or would I be ok in using a base of 50mm EPS and then 150mm PIR above this? (100+50mm Celotex)

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

@embra did you undertake this work. I have a very similar Bow window (the upper decorative panel looks identical) but mine protrudes a bit further, so interested to see how you got on as we're looking to replace the 30+ year old windows as well this year.

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.

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.

spittal

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

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.

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 )