Attic insulation

C Lo

I was up in the attic today doing a quick survey as the house is freezing and I'm going to give this a go next week. Plan is to top it up to 300mm. There is very little insulation up there currently. It is missing in places and 50mm (found old some insulation bags up there that said 2") everywhere else. I would need to top up the 50 to 100m, but I am considering dumping it and putting down new 100. I don't think it's possible to buy 50mm roll to top it up that way. The other option would be to fold / move the existing insulation so that it's doubled-up and then buying about half the amount of 100 to cover the remaining. Is this a good approach?

Regarding the wiring for lights - Is it ok to just insulate over them? We just have regular lights - cable with bulbs at the end as opposed to spot lights.



And the last thing is that the width of the joists is about 320mm - I see most rolls are preforated to 380m, should I trim the excess?

I took some pictures but can't post them as I am new. but they are all on tinypic:

Sleeper12

C Lo wrote:

Regarding the wiring for lights - Is it ok to just insulate over them? We just have regular lights - cable with bulbs at the end as opposed to spot lights.

If you have an electric shower you definitely don't want to insulate over this cable. If you have any spot lights don't insulate over these. Don't insulate under the water tank and don't go all the way into the eaves.

C Lo

Sleeper12 wrote: »

If you have an electric shower you definitely don't want to insulate over this cable. If you have any spot lights don't insulate over these. Don't insulate under the water tank and don't go all the way into the eaves.

Thanks! When you say don't insulate over the cable for the shower, do you mean it needs a special housing, a gap, or do I just insulate under it and lay the cable on top?

funkey_monkey

You can get 'Downlight Covers' to place over spot lights so that you can insulate over them.

listermint

C Lo wrote: »

Thanks! When you say don't insulate over the cable for the shower, do you mean it needs a special housing, a gap, or do I just insulate under it and lay the cable on top?

Try lay cable on top,you don't want to insulate and heat cables.

Also leave the old stuff in place it's pointless removing it it's better than throwing it out as it still has a purpose.

Go all the way to eaves but not out onto them. What that means is cover the cap of the wall so that you aren't leaving cold spots in the rooms below. But don't block out the eaves to air flow into attic space.

C Lo

funkey_monkey wrote: »

You can get 'Downlight Covers' to place over spot lights so that you can insulate over them.

I don't have spotlights but what to do with cables for regular lights?

C Lo

listermint wrote: »

Try lay cable on top,you don't want to insulate and heat cables.

Also leave the old stuff in place it's pointless removing it it's better than throwing it out as it still has a purpose.

Go all the way to eaves but not out onto them. What that means is cover the cap of the wall so that you aren't leaving cold spots in the rooms below. But don't block out the eaves to air flow into attic space.

I was just going to ensure the plaster board which makes the ceiling was all covered. Is the cap of the wall a bit extra outside of this, or would it be under the plasterboard?

Sleeper12

C Lo wrote:

I don't have spotlights but what to do with cables for regular lights?

Light cables are fine. It's really only electric and cables you'd need to worry about.

budhabob

just to warn, its a horrible dirty job, but doesn't take too long, and you will notice an immediate difference. We did it last winter.

Would recommend you wear long sleeves, gloves and a mask as a minimum.

C Lo

budhabob wrote: »

just to warn, its a horrible dirty job, but doesn't take too long, and you will notice an immediate difference. We did it last winter.

Would recommend you wear long sleeves, gloves and a mask as a minimum.

Thanks. Just bought some masks and overalls

listermint

C Lo wrote: »

I was just going to ensure the plaster board which makes the ceiling was all covered. Is the cap of the wall a bit extra outside of this, or would it be under the plasterboard?

The cap of the wall will be the top of the outside wall of the house. (just past where the plasterboard finishes. Depending on if its cavity block or cavity with twin leaf the cap can be wider in different scenarios. Just make sure you go at least 2 inches onto the cap / wall. That way you are covering the plasterboard of each room and not creating edge cold spaces where air can travel freely. (avoid mould spots / cold spots in the corners of your bedrooms)

C Lo

listermint wrote: »

The cap of the wall will be the top of the outside wall of the house. (just past where the plasterboard finishes. Depending on if its cavity block or cavity with twin leaf the cap can be wider in different scenarios. Just make sure you go at least 2 inches onto the cap / wall. That way you are covering the plasterboard of each room and not creating edge cold spaces where air can travel freely. (avoid mould spots / cold spots in the corners of your bedrooms)

They were pretty clear once I got a closer look. Pretty much bang on as you said it. It can only be described as the top of the wall. It's a semi-detached house and obviously their is an obvious cap on three side. What do do on the attached side? Roll all the way up to the boundary wall? Thanks for your help!

listermint

C Lo wrote: »

They were pretty clear once I got a closer look. Pretty much bang on as you said it. It can only be described as the top of the wall. It's a semi-detached house and obviously their is an obvious cap on three side. What do do on the attached side? Roll all the way up to the boundary wall? Thanks for your help!

Yep right up to the wall

Heroditas

C Lo wrote: »

Thanks. Just bought some masks and overalls

And wear old clothes. You'll be surprised how much you'll sweat doing it, even in winter!
Gloves too. The stuff is very itchy!!

fritzelly

Heroditas wrote: »

And wear old clothes. You'll be surprised how much you'll sweat doing it, even in winter!
Gloves too. The stuff is very itchy!!

This +100 and surprising how hot an attic gets

C Lo

listermint wrote: »

Yep right up to the wall

Great. There is a joist about a fists width away from this wall which has no insulation currently. Basically a big cold strip at the edge of every room!

Danville

I have spots coming through in a ceiling of a bedroom in my 13 year old extension.
This first happened about four years ago.
I double painted the ceiling and put another layer of insulation in the attic overhead. It is not happening again and there even appear to be damp spots in the corners of the room
If the insulation goes out under the eaves might this be the cause of my problem, if so why exactly?
How should I fix the problem?
Thanks in advance

C Lo

So far, so good. I have even upgraded the ventilation.

budhabob

C Lo wrote: »

So far, so good. I have even upgraded the ventilation.

Oops?

listermint

Sorry to hear!

Easily rectified though its just plasterboard as long as no one was injured your good!

not ideal but sure look it happens to the best of tradesmen.

C Lo

All sorted now and have first layer done. Several bin bags of junk cleared. I have a bag of these cabling which was either tied up or bundled around the place. Anyone know what the is is from (re-wiring?) and if it can be recycled?

Gargamello

Planning on doing my attic in the coming weeks. Where is the best/cheapest place to buy rolls of insulation? Looking to put 200mm on top of the existing 100mm. So intend on buying rolls of 200mm assuming that is the easiest and most cost effective approach?

Thanks.

raxy

Gargamello wrote: »

Planning on doing my attic in the coming weeks. Where is the best/cheapest place to buy rolls of insulation? Looking to put 200mm on top of the existing 100mm. So intend on buying rolls of 200mm assuming that is the easiest and most cost effective approach?


Thanks.

https://www.woodies.ie/building-materials/insulation

I got some cheaper before off adverts.ie but didn't see much there. There was some there for 15 but never heard of the brand. You could look them up to compare

listermint

Tbh shop around different places have different offers at different times of year.

I'd phone places up to get prices.

I got mine from Goodwins as it was the best price at the time. But this changes monthly.

Some do buy 2 get 1 free

Gargamello

raxy wrote: »

https://www.woodies.ie/building-materials/insulation

I got some cheaper before off adverts.ie but didn't see much there. There was some there for 15 but never heard of the brand. You could look them up to compare

That Woodie’s sale price is probably as good as I’ve seen. I’ll order some of those. Thanks for that! Nearly half price. Good spot.

fred funk }{

Phone your local builder merchants and ask for a deal. They're normally a lot cheaper than Woodies etc.

Lumen

Gargamello wrote: »

That Woodie’s sale price is probably as good as I’ve seen. I’ll order some of those. Thanks for that! Nearly half price. Good spot.

The 200m earthwool from Woodies is 4.64/sqm.

It's under 4.50/sqm from a builders merchants.

The Woodies rolls are smaller so not directly comparable unless you do the maths.