thetdog666

there is also 2 exterior walls i can go with 50mm pir on top which will make a big difference. I will be double checking that when i get home in a few weeks

ok il double check 90mm is good. Im sure it will make a big difference if I do it and this is the time while I'm getting a new kitchen

I'm stripping everything out start of next month. Il see if 90mm will fit ok. Would pushing the 80mm PIR right back and leaving an air gap at the front be better? New kitchen is really tight so literally ever mm counts. I will get away using 25mm most places but one wall will need 20mm

I will have a look over the next couple of days. Say I was to go the 80mm pir then 20mm ontop would any vapour barrier be required then?

That's the method I was going for but again using 75mm pir instead. My joists are 90mm thick so thought 100mm mineral wool would help much

Wow thanks for putting that all Into perspective. I thought PIR would be alot better than mineral wool. Say I went with 100mm mineral wool and 20mm pir over the top would I need a vapour barrier? Thanks Steven

The studs are only 90mm thick and not sure if 600mm or 400mm apart that's why I was going for PIR to get the u value up. My house loses temperature quite quick so trying to rectify that while I can. I did price up 100mm insulation slabs but I'm sure the PIR actually came In cheaper. I currently have netting and 100mm under the suspended floor. I'm going to take the floors up to. Do you recommend I keep with rock wool for the floor aswell?

Yeah that's right hahaha.

That drawing I posted up is off another page. It is the most similar one iv come across to mine. My frames inside is only 90mm thick.

Of the room? 6m x 3.4m

Sorry OSB is fitted on the outerside with membrane on the outside side of the OSB. This is a drawing of one I found off the net. I didnt make it up so is slightly different to what i have. I heard there can be a tolerance with the timber frame studs and people have had trouble trying to fill it fully as the insulation sticks slightly past the timber frame. Answered above. OSB with breathable membrane Kitchen only just now but ot takes up 1/3rd of my downstairs. Livingroom and dining room next year (if there is a notable difference in temperature) which would be 80% of my downstairs done.

Hello, The drawing above is missing the osb and membrane on the outer side of the OSB. Thanks

yeah I would have to do that so maybe not the best. How would I fix the vapour barrier though to the wall?.....Would staples into pir work?

So the VCL is stapled to the 40mm x 20mm battens. So technically over the "top" of them. Celotex have 20mm PIR No pir between the battens. This is the service void where I will be running electrical cables. The illustration above is the exact way I would be doing it.

Yeah I think your right about the make up of the house. All plasterboard will be coming off of ceiling and external walls. I currently have 100mm wool(yellow itchy stuff) in the walls and floor. I have attached a picture I have found on another page of what I am planning on doing. My frame is only 90mm deep so 80mm is the max I can go for. Space is also an issue so am only going for 20mm on the face of the battens. Im now starting to think that the vapour barrier goes over the battens (just behind the plasterboard if looking from inside). What do You think? Thanks S