[Closed] Roof insulation depth - any point in adding more?

Yes, definitely. 220mm is the minimum and another layer rolled out across in the opposite direction will make a big difference. I've got 3 layers now up to 500mm because the stuff was going so cheap last winter.

Horrible job though, I agree.

I've been using 100mm recycled polyester recently. It's about twice the price of glassfibre but much nicer to work with. I get it from Casto which is owned by Kingfisher so there's a good chance you'll find some in B&Q.

Absolutely. I had about 40cm in my loft, and I added another 40. It made a big difference to not only the warmth but also the noise from outside the house.

Yes + 1

I have 270mm in the barn: 100mm between the rafters then 170mm perpendicularly.

formerly an eco-building designer here, and I say YES.

It's the cheapest way you can improve the fuel efficiency of your home.

Just be sure not to block the ventilation holes under the eaves that allow air to circulate around the roof timbers.

AP

Yep, fill in between the joists and then go on top perpendicularly (if that makes sense)

Alex.. elaborate on that ventilation thing - I thought the purpose of the eave holes was to ventilate the entire loft, and I figured that since I have plenty of open spots I was ok. Are you saying that every rafter needs clear space around it?

you need to leave a reasonable air gap ( 100mm ?? ) where the roof comes down to meet eaves so that the air can get up through the eaves, through the gap and into the loft space.

i.e. dont cram it right down into the corners

also have been doing my loft, should i avoid putting my insulation rolls over electric wires??

no problem in insulating over wires. fill yer boots (or your loft in this case)

if you have less than 300mm you might find you can get subsidised to get it up to standard. local authorities have the funding - you just have to ask for it.

I have some GU4/MR11 downlighters recessed into the bathroom ceiling. At the moment, there is no insulation over them. What's the best way of dealing with this? Some sort of box/cover in the loft and then insulate over the while lot??

Yes..

Was up in a pals attic tonight and noticed the same thing as Druidh mentioned.
The attic was recently reinsulated and has the certificate pinned to a rafter. But.....the downlighters have no covers/boxes whatsoever.
Know from the "Holmes on Homes" programme (Canadian) that a cover should be used.
Any suggestions for a UK supplier ?

You should be able to find metal light caps in any electrical wholesaler cheap, cover them with those and then you can insulate round. I have always left a small breather hole above all our downlighters as recommended by our builder. They do get really quite hot.

druidh & stucol

The following link should hopefully show what you are looking for

[url= http://www.screwfix.com/p/halolite-downlight-insulation-guard-220mm/97932 ]downlight hood[/url]

Clay flowerpots can also be used as covers

theres a bit of confusion in here as to what fire hoods do.

Generally speaking they are sold to maintain the fire integrity of the ceiling/floor.

They can be used to protect joists that are close to halogen down lighters, but oddly not necessary.

With LED down lighters they're not necessary at all.

Rock wool insulation wont combust from a downlighter.

As far as I can find out though, none of that is documented in the regs. Its a bit of a black hole.

those ones aren't fire hoods, they just stop the insulation from lying really close to the light fittings. They offer some air circulation and should assist to prevent (or reduce) any associated equipment from being damaged from the heat build up say transformers or where some people have just used open connector block with twin and earth cables really close to the lamp.

Fire hoods "should" form a seal if there is a fire from below, creating a seal between the room and the floor above and providing a fire barrier.

I was going to ask this the other day, as I have 5 rolls of insulation, and a well insulated house, might as well chuck it in then! Good times, keeping bills down, being eco and freeing up some space in the basement!

Oh well..... more crawling around in the loft then 🙁 Did I mention I hate putting insulation in??

Slight hijack - I'm planning to add another 200mm to my current 150mm.

It's slightly cheaper to go for 2 x 100mm rather than 1 x 200mm. Any real world differences? I wondered if the 2 x 100mm runs crossed over at 90 degrees would provide better insulation?

sharkbait - get yourself a paper suit to do it in. Tape the cuffs up. Get a disposable face mask while youre in the shop too.

By having 2X100mm you can lay each roll at 90º therefore reducing draughts and air flow. How significant this is, I don't know.
[url= http://www.theyellowhouse.org.uk/themes/insula.html#in6 ]http://www.theyellowhouse.org.uk/themes/insula.html#in6[/url]

I have some GU4/MR11 downlighters recessed into the bathroom ceiling.

Have you changed them to LEDs yet? Big reduction in consumption if you haven't.

Tape the cuffs up

The price of the good GU10 LED replacements is coming down still.

I have about 100 of them in the barn and before buying that many bought about a dozen or so as testers to work out which ones to commit too as you can never be sure of beam angle, or colour temp until you have one to test.

The most expensive ones I got were about £20, the cheapest were £3.50

about 3/70 £3.50 ones have failed.
None of the (20 or so) expensive ones have.

Before you add extra insulation look at the build up of the existing. Then look up the requirements for ventilating cold roof spaces/underside of roofing felt.

Then make sure you understand interstitial condensation and how to avoid it (to be safe you may need to take out all your existing insulation and install a properly sealed vapour barrier directly over your ceiling before you put any extra insulation in).

If your electrical cabling the answer is it depends on its sizing, its loading, and how old it is.

The price of the good GU10 LED replacements is coming down still

when are they going to appear on dealextreme ??

sharkbait - Member
Oh well..... more crawling around in the loft then Did I mention I hate putting insulation in??

I did a load at the weekend and it was a real chore. We've got a lot of boarding down & a very shallow pitched roof. I have added insulation mainly to the area that is too low to access anyway. Crouching for hours, going back and forth moving boxes, rolling out the insulation, shoving it into place while lifting cables etc. What a ball ache! But at least it's done. There is a large unused area of boarding at the end of the loft (we just don't need that much storage space) and I plan to cover that too, but couldn't face it last weekend. I was done in, so will do it another day.....

Stoner - any links to a site selling these LED GU10s?? We've got 3 in the kitchen & 6 in the bathroom & I'd be keen to change them. Any recommendations for colour temp/beam angle would be appreciated.

Joining the hijack, my kitchen has GU10s and they keep blowing after a few months (not all at once) will the LEDs last longer? Also should I get someone to look at the electrics?

Yes - the LED GU10s last a lot longer. Problem at the moment is that the brighter ones are very, very expensive, seem to have a limited spread of light (spot more than flood) and are often longer than a standard GU10 - so stick out from the light fitting.

Just realised how cheap the insulation currently is at B&Q, so plan to add some more insulation to my attic.
I noticed that there was no insulation under the cold water tank in the attic, should I insulate this area? The tank has a jacket, and is lived in all year round, would I run the risk of the tank freezing?

As a DIY numpty, what do you do when you've got a partially boarded floor in the loft and want to keep it? I take it there's little point in lifting the boards and packing more under there as it will compress?

Compressed insulation is still insulation.

I put in a suspended floor with enough room underneath it for tons of insulation...

Problem at the moment is that the brighter ones are very, very expensive

Yes but they are say 4W instead of 40W. So if you have 15 in a kitchen that represents a saving of 500W! So if they are on for two hours could be a unit a day, or say 10p. That's £30 a year, so payback in er.. 15 years.. hmm... Lots of energy saving though.

thesurfbus - Member
Just realised how cheap the insulation currently is at B&Q, so plan to add some more insulation to my attic.
I noticed that there was no insulation under the cold water tank in the attic, should I insulate this area? The tank has a jacket, and is lived in all year round, would I run the risk of the tank freezing?

Yeah - insulation currently £3/roll in B&Q. I tried to get 8 rolls into the back of my Ibiza last weekend. They didn't fit. I could only get 4 in! Bloke in large Merc van found it quite amusing....

I don't think you are supposed to insulate under the cold water tank.

shedbrewed - Member
As a DIY numpty, what do you do when you've got a partially boarded floor in the loft and want to keep it? I take it there's little point in lifting the boards and packing more under there as it will compress?

This was my problem - most of the loft was boarded. The edges were partially boarded, but not fastened down so I lifted them all up.
We use a fair amount of the loft for storage so didn't want to get rid of all the boarding in the rest of the loft. I added more insulation to the edges of the roof space, although was careful not to push it right to the edge as this can cause problems with condensation/damp I think. I've moved all our stuff into as compact a space that I can, while still being able to get to it, and when I can muster the willpower I'll be covering the remaining space with more insulation (over the boards).

You can buy insulated boarding, but it will be expensive compared to normal insulation & I'm not sure it's any more effective than the same depth of rock wool stuff....

molgrips - Member
Compressed insulation is still insulation.

I put in a suspended floor with enough room underneath it for tons of insulation...

Is that right? I would have thought if you are compressing the insulation you are not really gaining the benefits of 'adding more' as you are just squishing it into the same space.
If you have no insulation, then fine stick some down, But, if the space under the boards is already insulated, squashing more in won't make much difference I don't think....You'll be losing the air gaps won't you, that make insulation work.....????

I got a load of these
http://www.energybulbs.co.uk/products/LED+Light+Bulbs/Deltech+LEDs+-+Full+Range/Deltech+GU10+LEDs/Deltech+Triple+High+Power+LED+5W+GU10+-+Warm+White/1489275929

although Id do a deal as that price should really have come down since I paid the same ish (5% discount for bulk I think) over a year ago.

^^ To insulate you need something that lofts in your loft (IGMC)

Continuing the hijack theme, we have quite shallow joists - approx 150mm if memory serves me correctly. Part of the loft is boarded, so should I lay over the top of the boards, or do I have to take them up and get rid of the boards (or put in a suspended floor)?