Insulation in attic before flooring - how much room should it have?

Suckit

My grandmother received the grant from the government to get her attic insulated a couple of years back, she got it, and I am going to lay a chipboard floor (18mm) on top of it using 2x2inch timber to raise it above the insulation for some storage.

I have only had a better look at it over the weekend, and I now think 2x2inch isn't high enough, but 4inch seems crazy.

Apologies for the sh*t drawing, but what is the best way to have the insulation? It is currently above the joists like the first image.

Should it be a bit above them, with a gap between the floor and the insulation, or touching the floor between the joists, or as it is currently, laying on the joists?

I had read somewhere that the rockwool should allow for condensation and expansion (or something along those lines), and that it could cause the ceiling below becoming bulbuos. But not sure if that applies to non-vented areas or if there is to much insulation packed between the joists etc.

I could be way overthinking it.

Roger Mellie Man on the Telly

Insulation should be both between joists (dia.3) and above joists (dia.1) to a total depth of 300mm. Insulation above joists to be rolled perpendicular to joists.

Suckit

Thanks. I have watched a few videos and only noticed that there should be two layers. There's not, I don't think so anyway. If there is, definitely not perpendicular.

It seems like there is one fairly thick layer, about the same depth as the joists, but not in between them. I was going ahead to press them down slightly (not compress) between the two joists so that they would touch the base, but a friend of mine said not to.

As it is, the 2inch lengths will be no good as they are below the insulation level. I want storage, but also to be able to walk on them, if only sometimes.

Should I get something like this? Although this doesn't say how many in a pack.

https://www.ecomerchant.co.uk/loftzone-storefloor-standard-kits.html

dathi

https://www.screwfix.ie/p/diall-loft-storage-stilts-210mm-12-pack/243GF?gclid=Cj0KCQiAqbyNBhC2ARIsALDwAsD4vNovtyb3GZpEUli8CtJ1M07zvFsP0lUVVvLFm61_EHod9YRruscaAvTeEALw_wcB&gclsrc=aw.ds

you can use loft legs available from most diy shops the insulation should be touching the plasterboard and as said above should be in two layers 150 between joists and 150 above joists

Suckit

Thanks. 👍️

It seems it might be cheaper (and possibly better?) to pull out all of the insulation and put down PIR insulation. Not sure if I have worked it out properly.

Biker1

https://www.boards.ie/discussion/comment/118293865#Comment_118293865

Forget about PIR. Will cost a small fortune, difficult to fit and lots of waste. Just make sure you have at least 300mm of insulation from the plasterboard up.