DIY loft insulation - need advice please!

LillieFlower

Hello everyone

My OH is planning a trip up into the loft to add some more insulation soon and as we're novices at this sort of thing we could do with a little advice...

there is already some insulation up there and we had a quote to have extra added under the government's grant scheme but it was going to cost £360 (after the grants! :mad: ) so I decided hubby should do it on the cheap instead!

The guy that measured up for the quote said we would need 200mm to get us up to current recommended insulation levels, and the loft is 45 square metres.

We were thinking about buying some fibreglass rolls from Wickes or somewhere but I can't stand the stuff as it gets everywhere, so when I spotted this on the Screwfix Direct website I got a bit excited :j :

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=76477&ts=71171

What we need to know though is if this is going to be ok to lay over the fibreglass stuff that's already down up there, and also whether this will equate to the 170-200mm thickness of fibreglass insulation that we've been told we need to get?

We'll want to board over some of the loft too so it would have to be ok for that aswell.

Could anyone help please?

Coveredinbees!!!!

I'm no expert but this is what I did.

In the area I boarded out I put down new 100mm insulation up to the top of the roof joist then put down chip board floor boarding. I used 8x2 sheets but loft packs are a better idea as getting the 8X2's in to the loft is a nightmare. The rest of the attic I left the old stuff in place and laid new 200mm across the joists so now I'm up to around 250mm in most of the loft except for the boarded area. On top of the boards I put in some old carpet as well. Remember all the old junk you will stick up in the loft will add to the insulation to a certain extent too.

I have a pretty big loft too and I don't remember it costing that much to insulate

savingallthetime01

go to b and q buy one get one free

pboae

The foil stuff you've linked to isn't meant for insulating an open roof space, you need something like space blanket which was also on 2 for 1 in B&Q recently, don't know if it still is. Other manufacturers make similar products too I think.

But you cannot put boarding over something like that. If you intend to board it anyway, you are probably better off going for insulated loft board to start with like this.

Be aware though that there are catches to insulating the loft. If you have spotlights or other lights embedded in the ceilings below, you must provide adequate ventilation for them. You also need to be careful about trapping electrical cables inside insulation, as they can over heat as well.

jamstaruk

how much are you looking to pay?

rjtyrell

pboae wrote:

The foil stuff you've linked to isn't meant for insulating an open roof space, you need something like space blanket which was also on 2 for 1 in B&Q recently, don't know if it still is. Other manufacturers make similar products too I think.

But you cannot put boarding over something like that. If you intend to board it anyway, you are probably better off going for insulated loft board to start with like this.

Be aware though that there are catches to insulating the loft. If you have spotlights or other lights embedded in the ceilings below, you must provide adequate ventilation for them. You also need to be careful about trapping electrical cables inside insulation, as they can over heat as well.

Just wondering why you can't put boarding over that stuff? cause I just have?

pboae

If you put boarding over something like space blanket you compress it right down (unless you have abnormally deep joist spaces). The air inside does a lot of the insulating, and the air gets squashed out of it making it relatively ineffective as an insulator.

The recommended depths for insulation are 200mm minimum and 300mm as the ideal. If you take 200mm mineral wool and squash it down to 100mm you have 100mm of inuslation not 200mm.

Not sure I have explained it very well, but hopefully you get the idea.

robv_3

If foil insulations work as advertised is a hot issue at the moment. A number of council building control officers will not accept them anymore due to them failing independent tests. The foil companies are reporting the tests are out of date and do not represent real life applications but other insulation methods pass without any issues. One of the foil makers state it should only be used with another type of insulation eg, fibre AND foil.

I've tried foil tec under a timber floor and are not impressed. We had to add fibre insulation to bring the floor to a acceptable level. One of the others foils we tried under a screen floor and you can tell the difference between a insulated and non insulated floor laid at the same time.

Its upto you......but I would not use it in my loft.

LillieFlower

Thanks everyone for your posts so far. It's given us plenty to think about!

We already have some insulation (I think it's fibreglass roll) in the loft and as we don't want to spend any more than £120-£130 to do everything (if possible) is it worth us just going for some boarding then? I reckon we must have already got around 10mm up there as the chap that gave us a quote recommended an extra 20mm (we didn't mention anything to him about possibly wanting to board it too).

The insulated board that pboae recommended looks good. Does anyone have any ideas about where to get that sort of thing cheaply and easily?