I need to insulate my flat garage roof, [cold deck] to a u value of .25, the
joists are 9 inches deep and I have to leave a two inch gap above the
insulation to provide room for cross ventilation. I have priced celotec at
nearly £700.00, is there a cheaper way, eg pad out the bottom of the joists
so that I can use 300mm of fiberglass, If so is there a minimum clearance
between flor and ceiling?
Is there a better way, does rockwool have a better u value than fibreglass?
If relavant the garage is constructed with a brick outer skin and a celcon
block inner leaf and is integeral to the house on one long side, the garage
is 15ft by 9ft and is to be used as a study/music room.
Any sugestions gladly accepted, Regards all, Tom

Tom wrote:
I need to insulate my flat garage roof, [cold deck] to a u value of .25, the
joists are 9 inches deep and I have to leave a two inch gap above the
insulation to provide room for cross ventilation. I have priced celotec at
nearly £700.00, is there a cheaper way, eg pad out the bottom of the joists
so that I can use 300mm of fiberglass, If so is there a minimum clearance
between flor and ceiling?
Is there a better way, does rockwool have a better u value than fibreglass?
If relavant the garage is constructed with a brick outer skin and a celcon
block inner leaf and is integeral to the house on one long side, the garage
is 15ft by 9ft and is to be used as a study/music room.
Any sugestions gladly accepted, Regards all, Tom


Shop around for a better price on the celotex. I would have expected a
lot less than that. IIRC an 8x4 sheet of 50mm is about 30 quid.


Nothing is as good.

You COULD use double the thickness in rockwool, but if it gets damp, it
rots timber faster than anything. I don;' think it would come much
cheaper, either. AND its a ******* to isntal.

Fiberglass and rockwool are almost the same thing.

15x9 135 sq. foot. I make that about 120 quid at sensible prices.

I have priced celotec at nearly £700.00, is there a cheaper way,
eg pad out the bottom of the joists so that I can use 300mm of
fiberglass, If so is there a minimum clearance between flor and ceiling?

No minimum height requirement.

Get quotes both for ecotherm and for seconds Kingspan from
http://www.secondsandco.co.uk/.

700 quid sounds very steep for 12m2. You might even get away with 4 boards,
if the joists are thick and going the right way. Worst case is 6 boards,
which is 17.3m2. Did the quote include the Celotex equivalent to K17 for
underboarding? Perhaps it included wall insulation?

Christian.

Christian McArdle wrote:
I have priced celotec at nearly £700.00, is there a cheaper way,
eg pad out the bottom of the joists so that I can use 300mm of
fiberglass, If so is there a minimum clearance between flor and ceiling?

Get quotes both for ecotherm and for seconds Kingspan from
http://www.secondsandco.co.uk/.

Hear, hear! I recently bought five 8x4 50mm boards from secondsandco:
price was 107 GBP including delivery.

David

Lobster wrote:
Christian McArdle wrote:
I have priced celotec at nearly £700.00, is there a cheaper way,
eg pad out the bottom of the joists so that I can use 300mm of
fiberglass, If so is there a minimum clearance between flor and ceiling?

Get quotes both for ecotherm and for seconds Kingspan from
http://www.secondsandco.co.uk/.

Hear, hear! I recently bought five 8x4 50mm boards from secondsandco:
price was 107 GBP including delivery.

(sorry, should've said: their delivery is 20 GBP + VAT - standard charge
AFAIK - if you want to do the sums for your own quantities)