Best attic insulation?

Sleepy

We've absolutely no insulation over most of the attic so want to install some insulation, I'm guessing the best return for my money is a simple matter of installing 300mm of rockwool/fibreglass.

As far as I understand it, I should be looking for the lowest possible U rating and installing a water tank insulation jacket.

Anyone know which of the various brands have the lowest U number? Or if I'm over-reaching? The attic isn't really suitable for storage so not too concerned if it'd be more cost-effective to use 400mm of a lower rated roll than to get the rolls royce stuff at 300mm or some similar solution. Basically I'm just looking to get best bang for buck!

Baggly

What space apart are the joists in the attic?

What height are the joists in the attic?

Would you be installing yourself?

This guide has a few tips, but doesnt mention anything regarding layers - id imagine you would need to have u value calcs actually done up to get a calc for bang for buck. I used the guide when doing my parents attic, so the tip on leaving a gap at the eaves for ventilation was one i wouldnt have done otherwise.

For ref, i think the insulation has a lamdba value, and the total build has a U value....?

listermint

v-e-n-t-i-l-a-t-i-o-n !!!

Sleepy

I need to measure the joist gaps and height alright but I've read enough guides to be confident I'm well able to do the installation myself. Any of the figures I've seen to get someone to do it in order to allow you to claim the grant are all well in excess of the cost of the materials.

My question really was to the cost v performance of the different brands / types of roll insulation: rockwool v fibreglass, manufacturer a versus manufacturer b etc.

Sleeper12

Sleepy wrote: »

I need to measure the joist gaps and height alright but I've read enough guides to be confident I'm well able to do the installation myself. Any of the figures I've seen to get someone to do it in order to allow you to claim the grant are all well in excess of the cost of the materials.

My question really was to the cost v performance of the different brands / types of roll insulation: rockwool v fibreglass, manufacturer a versus manufacturer b etc.

Good quality and a great price
http://www.homebase.co.uk/en/homebaseuk/knauf-earthwool-loft-roll-200mm-394101

mashed13

Sleepy,

Have you got your insulation done ?

I'm looking for answers to the same questions you had, price and brand ratio. There seems to be abundance of Fiberglass insulation brands and all vary in price, best I could find online is at Goodwins, Earthwool 200mm 6sq/m 20e a pack for 15+ packs, works out at just over 3e per sq/m.

Other places have plenty of different options Isover, rockwool etc but they seem to be double the or even more in price.

Any advice? Anybody is willing to list some differences between each ?

Thank a mil

M

Baggly

Lambda is the performance value on insulation products, so just make sure you are comparing like with like.

For €3 per m2, i would be thinking that is your standard performance loft roll (probably lambda 44, which is the lowest you can get for mineral wool afaik). Isover and Rockwool have similar performance wools, but would have higher priced ones for better performance product too!

I can see from a quick look on goodwins and woodies that the roll you are talking about doesnt declare the lambda, which makes me think it probably is 044 roll (they dont declare it because its so low).

200mm of 044 in your attic will do the job on a retrofit, but if you put in a bit more cash on a higher lambda 200mm roll, you will get better heat savings.

Sleepy

mashed13 wrote: »

Sleepy,

Have you got your insulation done ?

I'm looking for answers to the same questions you had, price and brand ratio. There seems to be abundance of Fiberglass insulation brands and all vary in price, best I could find online is at Goodwins, Earthwool 200mm 6sq/m 20e a pack for 15+ packs, works out at just over 3e per sq/m.

Other places have plenty of different options Isover, rockwool etc but they seem to be double the or even more in price.

Any advice? Anybody is willing to list some differences between each ?

Thank a mil

M

I'm afraid I've been procrastinating on this job for longer than anything else in the house, chiefly because my attic has a height of approx 1 metre at it's highest so it's one I've been dreading!

BrokenArrows

Sleepy wrote: »

I'm afraid I've been procrastinating on this job for longer than anything else in the house, chiefly because my attic has a height of approx 1 metre at it's highest so it's one I've been dreading!

Ideally break the roll up into strips of the correct width before bringing them up into that narrow space. Then have someone pass them up to you.

It will suck alright but shouldnt take too long. Maybe spread it out over a few days.

Calahonda52

Sleepy wrote: »

I'm afraid I've been procrastinating on this job for longer than anything else in the house, chiefly because my attic has a height of approx 1 metre at it's highest so it's one I've been dreading!

so the roof is almost flat?
what is the roof make up?
is there ventilation at the eaves?

Sleepy

BrokenArrows wrote: »

Ideally break the roll up into strips of the correct width before bringing them up into that narrow space. Then have someone pass them up to you.

It will suck alright but shouldnt take too long. Maybe spread it out over a few days.

A good tip, thanks!

Sleepy

Calahonda52 wrote: »

so the roof is almost flat?
what is the roof make up?
is there ventilation at the eaves?

Not quite flat, it's a 1920's build with hipped ceilings on the upper floor. Yes, there's ventilation at the eaves.

Calahonda52

Sleepy wrote: »

A good tip, thanks!

It may not be depending on the answers to my questions

Are there power cables in attic?

Baggly

Sleepy wrote: »

A good tip, thanks!

Some of the 044/040 rolls come presplit at 600 and 400 centres fyi - save you some work maybe.

mashed13

Pter wrote: »

Lambda is the performance value on insulation products, so just make sure you are comparing like with like.

For €3 per m2, i would be thinking that is your standard performance loft roll (probably lambda 44, which is the lowest you can get for mineral wool afaik). Isover and Rockwool have similar performance wools, but would have higher priced ones for better performance product too!

I can see from a quick look on goodwins and woodies that the roll you are talking about doesnt declare the lambda, which makes me think it probably is 044 roll (they dont declare it because its so low).

200mm of 044 in your attic will do the job on a retrofit, but if you put in a bit more cash on a higher lambda 200mm roll, you will get better heat savings.

That's some good advise.

Originally I was thinking of putting in 400mm now I'll need to look into lambda rating first, never hear of it.

Sleepy, I hope you ain't scared of confined spaces

Sleepy

Calahonda52 wrote: »

It may not be depending on the answers to my questions

Are there power cables in attic?

Would need to double-check but I'd assume there'd be some wiring for the bedroom lights at least...

Baggly

There are other considerations as well like installation (some of the rolls are shocking for dust) and some arent - again, you will pay a bit of a premium for the better ones.

Sleepy

mashed13 wrote: »

Sleepy, I hope you ain't scared of confined spaces

I wouldn't go so far as to say I'm claustrophobic but I don't enjoy it!

Not rich enough to pay others to do my dirty work though! Luckily I only have about 24 sqm to do. For some insane reason the loft over the extension has insulation but they never bothered to do the original front of the house!

Sleepy

Calahonda52 wrote: »

It may not be depending on the answers to my questions

Are there power cables in attic?

Should have mentioned, the lights in the bedrooms are just regular pendents, no downlighters if that's what you were thinking of?

rustynutz

Sleepy wrote: »

I'm afraid I've been procrastinating on this job for longer than anything else in the house, chiefly because my attic has a height of approx 1 metre at it's highest so it's one I've been dreading!

I feel your pain, I recently upgraded the insulation in the crawl space of my dormer, this space is 900mm high x 900mm wide, triangular shaped, and had one access point each side, so had to crawl 10m at the furthest point, this is probably why it took me over 10 years to get around to it! Its worth doing though, I noticed a big difference in how long the house retains heat. I already had 150mm of insulation between the joists, I went with 200mm top up, bought in B&Q

I hope you like spiders! Good luck

Outkast_IRE

I know there is cheaper but i do like the rockwool for this job, it also has good performance in a fire, so thats always a plus.

I do find some of the glasswools are bad for going a bit flat after a few years for whatever reason, but the rockwool seems to hold its shape well.