[Closed] Loft insulation - tips

It’s quite a big space and want to be able to use one side for storage so guessing I’ll need some feet for the boards?

Insulate the inside of the roof rather than floor of the loft if you want to maintain usable loft space.

Remember to leave an air gap to prevent interstitial condensation.

I've done this to our house recently.

Put the boards up on Loft Legs; I found Wickes did these cheaper than anywhere else. I got the insulation from Wickes too; it is cheaper online but delivery prices for this kind of stuff were massive so it ended up more expensive. I dare say you could probably get it cheaper from a builders merchants or something but I didn't find the difference worth the faff.

I got a pack of loft boards and chopped them in half to make six moveable boards to stand / sit / lean on while working up there. Get some trousers with pockets for knee pads in, you'll spend ages kneeling down and its hell without them. Some kind of face mask is essential too otherwise you'll be breathing in all sorts of rubbish and coughing all day at best.

Get as much light as you can get, as the corners of the roof are dark! Headtorches are okay, but bigger fixed lights are better. Don't lay insulation down on top of your phone you were using as a light, it'll take aaaaages to find it...

It's a crappy job but it made a difference and I have the satisfaction of not having to do it again.

Insulate the inside of the roof rather than floor of the loft if you want to maintain usable loft space.

Wouldn't that simply result in wasting more energy heating the loft too?

Interested in this. Out house has a pretty pathetic layer of maybe 10 mm of rubbish looking glassy/wool looking stuff. Probably circa 1984.

I need to increase this (remove the old stuff first?) while not burying the new extractor fans working around water pipes and electric cables!

Given the enormous number of joists I'm not going to board out much.

I prefer to cross batten the existing battens with 4x2 timber. I think it makes for a sturdier floor, but I'm sure the legs are fine. You'll get slightly less insulation but still a good amount. As mentioned, don't go right to the edges and block the ventilation. For storage I'd just insulate the floor and keep it as a cold space. Be wary of insulating over lights and cables although this is much less of an issue with LEDs.

Given the enormous number of joists

I believe this is done as they don't make joists to best fit each build, they just build a standard size which they make in the thousands then bung loads in. Apparently it is much cheaper and quicker to bung up Euro Standard Housing that way. Our loft is the same - it's a maze of woodwork up there.

Wouldn’t that simply result in wasting more energy heating the loft too?

No, it would result in saving less energy heating the loft. A subtle but important difference 😉

It depends on what's in the loft aleady and what he intends to store in it.  If there's water pipes and tanks in it I'd prefer to trade off the extra energy expended for the comfort of having the pipework all cosy in the dead of winter.

I believe this is done as they don’t make joists to best fit each build, they just build a standard size which they make in the thousands then bung loads in.

Say what?

I think he's alluding to pre-build trusses from a specialist supplier, as opposed to constructing in situ by hand with nails like when lump o' coal cost thruppence and hovis bread came from down the cobbled hill.

I think he’s alluding to pre-build trusses

....which use  smaller timber profiles than traditional joist construction to make them lighter for manual handling and to make the whole roof light enough to build at ground level and then crane on in one go as it eliminates a shit load of dangerous working at height.

Nothing to do with standardizing timber sizes at all.

But they do make loft conversions a bit tricksy.

Mind you, our roof, despite being purlins and struts and whatnot, would still a bit of a tricksy loft conversion unless we were borrowers, as it is only about 4' high at the ridge. Cost cutting, 1812 style.

which use smaller timber profiles than traditional joist construction to make them lighter for manual handling and to make the whole roof light enough to build at ground level and then crane on in one go as it eliminates a shit load of dangerous working at height.

Yeah, that'll be it. Lazy sods making my loft approximately 98% wood. My last house just had two great big bloody timbers in and a massive loft room was created with minimum fuss.

Where the trusses of our main roof intersect the rafters of a bay window gable there's a space that I physically can't get into, none of the holes are big enough! There isn't enough insulation in that bit... is it okay to get your two year old to do it instead? I'm sure with a bit of direction they'll manage...

is it okay to get your two year old to do it instead?

Only if you pay them a farthing a week and let them sleep under your bench in the workshop. Shoes optional.

Jon Taylor

Subscriber

Interested in this. Out house has a pretty pathetic layer of maybe 10 mm of rubbish looking glassy/wool looking stuff. Probably circa 1984.

I need to increase this (remove the old stuff first?) while not burying the new extractor fans working around water pipes and electric cables!

Given the enormous number of joists I’m not going to board out much.

I had that in my house. I've replaced it with a 100mm layer of Knauf Eko for now and it's made a noticeable difference. The worst bit was removing the old 10mm fibreglass. I wish in hindsight I'd just laid it over the top. At least I won't have to deal with that insanely itchy shite again.

How much do you improvement do you gain by going to the modern (350mm?) standard from 100mm? The expense & time needed will be considerable.

is it okay to get your two year old to do it instead?

When I was a kid (granted a bit older than two, but still very young) I was sent under the inspection hatch in the floorboards to crawl through the footings (there were little holes punched in the blockwork) to the far side of the house, take some wiring and crawl it back. I can't have been more than about 8 or 9 but I still remember it like it was yesterday. 🙂

Thanks grandad.

When we had ours done there was almost no difference in price between an energy company subsidised professional installation and buying the insulation itself.

When I did ours I laid 100mm stuff between all the joists, then a layer of shiny foil stuff (no idea if it's any use but it's cheap enough) then just fixed loft boards over the top of that until I ran out.

Ours is just storage, but the insulation has definitely made a big difference. The boarding is a little haphazard as, like everything in our house all the joists are a bit wonky.

Mask is a must if yours is anything like ours was. And if you have a beard, shave.

There isn’t enough insulation in that bit… is it okay to get your two year old to do it instead?

When i were t'lad.

I was sent down the eaves to fetch cables this in volved negotiating a 90degree bend in a small triangular tube of very old and manky joists and rafters. I think my dads plan was to come in through the wall lathe and plaster if it went pear shaped because there was zero chance of turning round.

I hope that was his plan anyway!