Between rafters insulation - cheaper then Celotex?

[David Pearson]

G'day.

I have a single-storey extension, with a shiny new roof (the old one was described by the roofer as "a bit ripe"). The old ceiling was a rotten mess, due to the leaks in the old roof, so I have pulled it all down and chucked it out.

Now I have a room with exposed rafters and sarking, which I need to insulate before hanging a new ceiling.

Tell me if I am wrong, but I plan to put between-rafters insulating stuff ... er, between the rafters, and make the new ceiling out of plasterboard nailed to the rafters.

The roofer recommended Celotex insulating slabs, but I am a wee bit gobsmacked at how expensive this stuff is. I am quoted 31 quid + VAT for an 8x2 slab (8x2 in feet), which works out at over 300 quid for my

3x3 (metres this time, excuse me) room (rafters 40 cm apart). That is only for 1 layer, and I need a second layer to meet the building regs! Even worse, I have a second room to re-ceiling under the new roof. So I am looking at more than 1200 quid to insulate the roof, on top of all the plaster- board etc.

So, if anyone can help me out with some advice on cheap, but still good enough, insulation, I will be very happy.

Regards, David Pearson (got a lovely roof, but no money, in Taunton)

[Lobster]

If you're going to insulate using Celotex, try contacting

for a price (I think they just do Kingspan, but hey). It's what it says on the tin - seconds - but is perfectly OK and a lot cheaper than your local builder's merchant.

David

[Mike]

I was going to say that :-) Excellent company (no connection)

And if you are hanging the ceiling independently of it so don't need it to be too flat or consistent, ask if they've got anything suitable. I got a huge load of 2.4*1.2m at 120mm thick for £10 a piece so you'd only need 3 or

4 of them to meet the regs.

Meanwhile I've got the warmest barn in town :-)

[philip cosson]

You could try actis tri iso super 9.

or staple it on the underside of rafters and use 25mm roofing battens to secure 12.5mm plasterboards to finish the roof. - or you could use a suspended ceiling.

Incredibly easy to use. about £11 per square meter. comes on 10 or 20 meter rolls 1500mm wide.

Celotex don't like it!

Philip

[Autolycus]

re-arranging to a moderately sensible sequence:

then

Would you buy anything from a supplier whose technical knowledge is such that they can include in their "definitions"

Heat/Warmth: Impression, feeling of comfort. State of matter characterised by the internal movement of matter characterised by internal movement of constituant particles

or indeed:

Desibel (db): Transformation of water vapour into droplets (fog,dew)

? This is in keeping with the literacy level of the rest of their site.

not so impressed, myself.

I would urge anyone contemplating insulation of a roof or wall not to do so until they've thoroughly understood "warm/cold" roof principles and thought through where condensation, including interstitial condensation, will occur.

I note, incidentally, that Screwfix have corrected in the latest catalogue (78) the error in 77 which claimed their Protect A1 roofing felt to be breathable. I wonder how many sweating roofs there will be as a result of that little misunderstanding.

[fred]

In article , philip cosson writes

[The Natural Philosopher]

Yiu WILL need an equivalent product,but in the quanitires you want, you should be able to get the price down by 40-50%.

Phone around all 'insulation suppliers' in yellow pages, and start talking deals.

[al]

I just bought some of that to staple up to my rafters to keep the attic a little cleaner and provide very minor thermal insulation. I was under the impression that it could be used on its own without causing condensation. I'm only planning to come down to about 1m from the eves with it rather than cover every last cm of the roof.

a

[Mike]

Provided you don't mind most of the heat passing through the roof.

[Rick]

100mm thick in 8x4 slabs is 27-28 quid in B&Q (chester), 17-18 quid for 50mm thick.

You will get the best compramise be doing 50mm between (leaving a vented air gap below the saking), and 50mm below the rafters. Then put the plasterboard onto that, to get a sloping ceiling.

Rick - who spent the weeknd puting the first bit of 1500 quids worth of this stuff into his roof.

[manatbandq]

Is that really Celotex? I just get blank looks when asking for it in any of the sheds.

MBQ

[Rick]

B&Q chester have a big sign on the door, cheepest kingspan anywhere, and they are right.

Rick

[tom patton]

If only I had read this before spending £600 on 50mm Kingspan-----ah well look on the bright side Ive got 100 square metres still to buy at half my present price of £36 per 35mm board.

100mm thick in 8x4 slabs is 27-28 quid in B&Q (chester), 17-18 quid

[manatbandq]

Is that a normal B&Q or a Wharehouse?

MBQ

[Mike]

None of the B&Qs (Warehouses or piddly little places) in Manchester have it.

[Rick]

I have noticed this, I use stockpot a lot too, and they don't have anywhere neer as much trade stuff as chester do.

[David Pearson]

Thanks everyone, for all the advice you have given. Most useful.

-David Pearson (original poster)