[Closed] Loft Insulation- complete loft space or part?

Why wouldn't you do it all if you're up there anyway?

Why wouldn’t you do it all if you’re up there anyway

Because it's not fun?
Although I do agree.... best to do the lot but not completely necessary.

I’m loosing the will to live, done 45m2 so far and another 10m2 to do in another part of the house!

Do the occupied parts of the house first and then return to the garage when you've recovered your sanity.

I would do the lot.

In the process of doing ours as there is approx 1" of some form of insulation up there.
Have taken all the old stuff up and replacing with 100 + 170mm.
It's actually quite a rewarding job to see it all looking new and insulated and the feet from Wickes seem to do a reasonable job of supporting the boards for storage.
I'll have done about 160m² of the stuff by the time I've finished
🥵

We have a squarish greeting space inside the front door and then half landing stairs so there is a large air space going right up to the upstairs ceiling which gets cold in winter. I double insulated above it, this had made a small difference, however the insulation extends over half of Micro’s room where it has made a massive difference. We have to keep the radiator turned down.

I did 100m2 in the roof above our old flat. MTFU and get on with it.

100m2

100 + m + Alt 253 = 100m² 🤩

It's not necessary to insulate an unheated area to a high degree, delta t an all that not being very high but insulating my detached garage roof has been great for keeping it cool in the summer and easier to warm up in the winter for tinkering.

Done it all now, was more like 75m2.

The last bit in the room below I’m not sure what to do. The flat space is 15m2 that I have put insulation in (was chuffin hard with only 2ft of headroom)

However the sloping bits above the wood are exposed and feed in to flat space. There is about 1ft gap between the plasterboard and the roof at this point. I considered putting insulation in but it would all but remove the gap. Should I just leave it or do I need to buy some kingspan type stuff to lay on it? Forgot to take a photo while I was up there! Rooms are heating up quicker 😁

I would try and get foam insulation board into the remaining area, you may find this part of the ceiling is more prone to mildew if its cooler and attracts any sort of condensation.

Are those stilt/leg things still stupidly expensive?

As stevied said Wickes was cheapest for loft legs when I did ours, and they didn't seem that expensive.

I hate doing it. I had hoped I never had to do it again but I've just scrounged a thermal camera and I've somehow missed a big triangle above our bedroom, bah!

Slight hijack - do you need an airflow gap between the top of the insulation and the underside of the boards?

I thought you did, but why are the plastic loft legs 170mm tall?

I don't think you need an airgap under the boards, just under the roof. The legs seem expensive but for the ease of install compared to installing long lengths of extra joists to raise the floor its worth it. From memory I think they are designed for 600mm spaced rafters so if you have 400mm rafters, you get less coverage per pack. So I installed mine in a diamond pattern rather than grid, if you measure diagonally between legs they are 600mm apart, you have to 'waste' a few around the edge of the board where they go every 400mm 🙂

You don't need a gap between the boards and insulation, just make sure you don't compress the insulation, but you do need a gap in the corner where the roof comes down to allow airflow from the soffits into the loft. In my loft the insulation goes right upto the corner where the roof intersects the floor, so i'm having to go and cut a few inches off the length of the current insulation before laying more down. Bit of a PITA.

To the OP I would insulate of the garage. Unless its completely isolated (which is sounds like it isn't) then you will create cold spots which will cause movement of air leading to drafts and heat loss.