Loft insulation, purchase

KaneToad

Have to tackle a loft insulation improvement project. There is some yellow fibre glass rolls already there but I want to lay some more on top.

1) Is laying on top a good idea?

2) What roll type insulation is the best bang for buck, a fella in work said he used Knauf?

3) Most importantly, where is the best place to buy the stuff? I assume the prices in Woodies are not the most competitive? Are there specialist insulation sellers? Where do the tradesmen buy their stuff from?

Thanks, as always.

listermint

Lay on top it's fine.

Any brand like knauff or earthwork models.etc are.good.

Price around yourself deals change all of the time. Yes check woodies but also check builders providers like Goodwin's, brooks, mahons etc etc

olestoepoke

I had the yellow stuff already between the rafters, not good enough. I got 200mm knauf roll, the brown stuff and rolled it out the opposite way of the joists and original yellow stuff underneath. Make sure its puffed up as you go, thats where the value is not squashed down and cover everything but crucially do not block the air from getting in via the soffits make sure plenty of daylight getting in where the wall plate is. I think 12 rolls did my house, a standard 3 bed semi.

the_pen_turner

olestoepoke wrote: »

I had the yellow stuff already between the rafters, not good enough. I got 200mm knauf roll, the brown stuff and rolled it out the opposite way of the joists and original yellow stuff underneath. Make sure its puffed up as you go, thats where the value is not squashed down and cover everything but crucially do not block the air from getting in via the soffits make sure plenty of daylight getting in where the wall plate is. I think 12 rolls did my house, a standard 3 bed semi.

very true but you should have atleast 400 mm

Corkey123

the_pen_turner wrote: »

very true but you should have atleast 400 mm

Wanna back that up. On what basis is 400mm the new 300mm?

the_pen_turner

on the basis that i used to work for a guy insulating attics, 2 layers of 200mm layed perpendicular to each other is what was specked using knauf


also more is better

listermint

Corkey123 wrote: »

Wanna back that up. On what basis is 400mm the new 300mm?

On the snuggly warm basis.

Yum yum

Dr_Colossus

Check B&Q, they often have 3 for 2 offer on loft insulation. It's fairly bulky stuff so difficult to get in any more than 3 or 4 rolls in a standard saloon car.

Roger Mellie Man on the Telly

Merchant rolls have greater m2 coverage than Woodies/B&Q rolls. SIG insulation will deliver for a fee.

KaneToad

OP here...thanks for all the info so far...

I've done some googling, with all the info ye have supplied. I couldn't figure out the apparently huge difference in prices...until I twigged the thickness element.

I found that Woodies have a sale at the min:

Knauff Earthwool, 200mm for 24.99 - a tenner off according to the website.

But then I see Goodwin's have the same 200mm but for 29.02.

However, on closer inspection, the Goodwin's product is a different length and covers 5.93m2 versus the Woodies offering which only covers 3.97m2.

Who'd have thought it was so complicated!! Different thickness, different lengths.

SouthWesterly

Woodies have 200 km of rock wool reduced to 24.

KaneToad

SouthWesterly wrote: »

Woodies have 200 km of rock wool reduced to 24.

I saw that, but its the short rolls. So not as much of a bargain.

I see that B & Q are doing Knauf Eko Roll 200mm (5.5m2 coverage) for £17 (roughly €19) if you buy 3 of them. They appear to deliver for free too... depending on order price. Odd that their site doesn't seem to price in Euro...

Is Knauff Eko Roll an inferior product to Knauff Earthwool??

ted1

KaneToad wrote: »

I saw that, but its the short rolls. So not as much of a bargain.

I see that B & Q are doing Knauf Eko Roll 200mm (5.5m2 coverage) for £17 (roughly €19) if you buy 3 of them. They appear to deliver for free too... depending on order price. Odd that their site doesn't seem to price in Euro...

Is Knauff Eko Roll an inferior product to Knauff Earthwool??

Do they deliver to Ireland. ?

Try build4less.ie
I got a good bit off them last year.

KaneToad

ted1 wrote: »

Do they deliver to Ireland. ?

I didn't follow through with the order.. but it looked like they did. Will try again and pay more attention!

Edit:
Delivery
If you are not able to get your items home from store, why not use our store delivery service?

Ask your local store for details of where they deliver.

Item size* Delivery charge Free
Small items €10 FREE delivery over €75
Large items €15 FREE delivery over €350
Bulk items €25 FREE delivery over €350

Edit again:
Shopping online
You can't purchase B&Q products online in the Republic of Ireland, but our colleagues in store are waiting to help when you visit.

KaneToad

BrownFinger wrote: »

Try build4less.ie
I got a good bit off them last year.

Just checked. Not competitive for insulation.

Yellow_Fern

you can buy loft legs to allow alot of insulation and stilll have floor boards.

olestoepoke

the_pen_turner wrote: »

on the basis that i used to work for a guy insulating attics, 2 layers of 200mm layed perpendicular to each other is what was specked using knauf


also more is better

If you read my post I said there was already insulation between the joists, this fills the up to the top of the joist and I rolled a further 200mm in the opposite direction or perpendicular. So there is a total of 400mm. More is not always better when it comes to insulation so thats terrible advice to give. An attic space needs air, needs to breath, so if you pile the insulation up too hight what happens where at the soffit? do you stop the insulation 3 ft from the soffit? Also if you do a quick internet search there are several reputable sites such as SEAI quoting that in Ireland 200 to 270mm is plenty for our climate, its dangerous to give advice to people about something you haven't a clue about.

listermint

olestoepoke wrote: »

If you read my post I said there was already insulation between the joists, this fills the up to the top of the joist and I rolled a further 200mm in the opposite direction or perpendicular. So there is a total of 400mm. More is not always better when it comes to insulation so thats terrible advice to give. An attic space needs air, needs to breath, so if you pile the insulation up too hight what happens where at the soffit? do you stop the insulation 3 ft from the soffit? Also if you do a quick internet search there are several reputable sites such as SEAI quoting that in Ireland 200 to 270mm is plenty for our climate, its dangerous to give advice to people about something you haven't a clue about.

More is better. No one advocated covering the soffits thats been covered in the first few posts.

Your being outrageous.

Also people can buy baffles to prevent insulation touching those areas should pulling it back from them be too strenuous

olestoepoke

listermint wrote: »

More is better. No one advocated covering the soffits thats been covered in the first few posts.

Your being outrageous.

Also people can buy baffles to prevent insulation touching those areas should pulling it back from them be too strenuous

more is not always better a quick search on several reputable sites will confirm this.

listermint

olestoepoke wrote: »

more is not always better a quick search on several reputable sites will confirm this.

Go on...

Yellow_Fern

I think the current building regulations say 300mm or 350mm. However it is better to have 200mm of very well laid wool without gaps than 3500 mm poorly laid. Many houses have strong breezes entering the edges of the attic that penetrates the wool massively reducing its effectiveness. In Sweden they use layers of paper to stop this. You could use PIR too. Quality rather than quantity.

olestoepoke

listermint wrote: »

Go on...

Go on where? Google it , you will be spoiled for choice confirming this. I'm not doing the work for you.

MicktheMan

the_pen_turner wrote: »

on the basis that i used to work for a guy insulating attics, 2 layers of 200mm layed perpendicular to each other is what was specked using knauf


also more is better

Just to put some figures on this

Adding 100mm of fibre insulation (between joists) to an uninsulated ceiling reduces the heat loss (conduction) by 89%.

Adding another 100mm layer over the joists (this assume 100mm joists) reduces the heat loss (conduction) by a further 6%

The next 100mm layer by 2%

And the next one by 1%.

So, the first 1 to 200mm, done properly is the most beneficial.

I often come across 3 to 400mm installed poorly because the attitude is generally "shure, the more the merrier" while had 1 to 200mm being done properly would have yielded a far better result.

olestoepoke

MicktheMan wrote: »

Just to put some figures on this

Adding 100mm of fibre insulation (between joists) to an uninsulated ceiling reduces the heat loss (conduction) by 89%.

Adding another 100mm layer over the joists (this assume 100mm joists) reduces the heat loss (conduction) by a further 6%

The next 100mm layer by 2%

And the next one by 1%.

So, the first 1 to 200mm, done properly is the most beneficial.

I often come across 3 to 400mm installed poorly because the attitude is generally "shure, the more the merrier" while had 1 to 200mm being done properly would have yielded a far better result.

Finally someone talking sense. The danger with people giving the wrong advice is that others will pile it up and inn5 years realise they've rotted all the rafters etc because the attic is not ventilated enough.

jimmyging

olestoepoke wrote: »

Go on where? Google it , you will be spoiled for choice confirming this. I'm not doing the work for you.

go on ...

SouthWesterly

olestoepoke wrote: »

I had the yellow stuff already between the rafters, not good enough. I got 200mm knauf roll, the brown stuff and rolled it out the opposite way of the joists and original yellow stuff underneath. Make sure its puffed up as you go, thats where the value is not squashed down and cover everything but crucially do not block the air from getting in via the soffits make sure plenty of daylight getting in where the wall plate is. I think 12 rolls did my house, a standard 3 bed semi.

How far back from the wall should the insulation be?

the_pen_turner

MicktheMan wrote: »

Just to put some figures on this

Adding 100mm of fibre insulation (between joists) to an uninsulated ceiling reduces the heat loss (conduction) by 89%.

Adding another 100mm layer over the joists (this assume 100mm joists) reduces the heat loss (conduction) by a further 6%

The next 100mm layer by 2%

And the next one by 1%.

So, the first 1 to 200mm, done properly is the most beneficial.

I often come across 3 to 400mm installed poorly because the attitude is generally "shure, the more the merrier" while had 1 to 200mm being done properly would have yielded a far better result.

i agree completely. 200mm fittet properly is better than 400 mm badly fitted. but 400mm properly fitted is better than 200mm properly fitted.
it doesnt always pay for the extra cost but there is a benifit to being thicker. . as time goes by and it looses efficiency you will be using more of the 'extra'

the_pen_turner

olestoepoke wrote: »

Finally someone talking sense. The danger with people giving the wrong advice is that others will pile it up and inn5 years realise they've rotted all the rafters etc because the attic is not ventilated enough.

obviously it has to be done properly.

listermint

olestoepoke wrote: »

Finally someone talking sense. The danger with people giving the wrong advice is that others will pile it up and inn5 years realise they've rotted all the rafters etc because the attic is not ventilated enough.

Interesting because there's been no wrong advice given. Can you point to a post that said cover your eves and block ventilation I'm supremely interested in this information. Perhaps you can Google it and find it on another site and show us here.

olestoepoke

listermint wrote: »

Interesting because there's been no wrong advice given. Can you point to a post that said cover your eves and block ventilation I'm supremely interested in this information. Perhaps you can Google it and find it on another site and show us here.

Maybe you should sign up for an IT course and learn how to use Google yourself.:D