Celotex Insulation

[wacomuk]

I need a load of 100mm celotex insulation for my loft. Does anyone know where i can buy it cheap?

Building control say it has to be 100mm celotex to meet the U value

[slater]

try www.sheffins.co.uk/ depends on how much you need,small amounts will have a delivery charge, or try your local roofing merchant most will negotiate a discount.

lewis

[Mark (smokey mow)]

Also take a look at Kingspan, Xtratherm and Ecotherm.  They're all essentially the same product as Celotex and will give the same U-values for a given thickness.

Different Builders Merchant's tend to favour one or the other and so prices will be higher if they're not a Celotex stockist.  Celotex is only made 1/2 mile from my office so we have quite an abundance of it here but it's still more expensive than some of the others named above so shop around for the best price.

[wacomuk]

i was going to use kingspan or ecotherm but if i do the building inspector will make me underdraw the rafters with an insulated plasterboard which then loses me head height

[Mark (smokey mow)]

i was going to use kingspan or ecotherm but if i do the building inspector will make me underdraw the rafters with an insulated plasterboard which then loses me head height

TBH you should do with Celotex as well.  100mm Celotex between rafters will only give you a U-value of 0.27 and for an insulated pitched roof you need to achieve a U-value of 0.2W/m2K.  To do this the rafters will need to be underdrawn with a further 20mm celotex in addition to the 100mm between the rafters.

Kingspan, Xtratherm and Celotex etc all have the same physical properties and an R-value in the region of 0.022-0.023W/mK so what works for one will also work for the other.

[Lurksalot]

I used insulated plasterboard as well as 100mm kingspann , it all helps not just in the winter but it helps keep it cooler in the blazing heat of the british summer ....

Ok I'll get my coat

But do it it anyway

[salexander]

Try secondsandco or BMD insulation.  Both online companies that do good deals with sensible delivery costs too.  I got a pile of Celotex from BMD to do my new garage.

[Chasmon]

I bought mine from Kellaways - cheapest I found and it is Celotex not Ecotherm (if that matters). I've gone for 150mm between rafters as I was advised that was minimum in ceiling but the walls have the same too. Insulating over the top wasn't required possibly as my rafters are 9"? I have had to tape all the joints with aluminium tape though to stop drafts from getting around the insulation.

[Mark (smokey mow)]

Yup 150mm Celotex is the minimum for a U-value of 02.W/m2K if you're cutting it all in between the rafters.

You need to tape the joints to create a continious vapour barrier (regardless of how you install the insulation), alternatively you could install a polythene vapour barrier between the insulation and the plasterboard.

[Man On The Clapham Omnibus]

As a slight aside, my son lives on the top floor of a block of flats in south London built in 1938, and it has an c.12" thick reinforced concrete roof finished with asphalt as a weatherproof membrane. Needless to say it is a heat loss nightmare so I have fixed Celotex boards (50mm as the thickest practicable) to the ceiling with No More Nails and battens, taped the joints with aluminium adhesive tape to make a vapour barrier, and fitted a Clipso stretch ceiling below it leaving a couple of inches air gap. The stretch celing, which most will not know of, is a perfect finsh and doesn't need a craftsman to fit - a competent DIYer can easily do it. Click for details