Hi I have recently joined this forum and would value some thoughts/advice on the following. I plan to insulate between the floor joists of a one roomed cellar in a Victorian terraced house.I have been told that Celotex is effective provided of course that there's adequate ventilation, which there is. Celotex(GA 3000) comes in different thickness from 40mm-130mm,at different prices of course. The joists in the cellar room are 140mm deep. Since I'm not sure what difference the thickness makes to the thermal qualities my question is if I opt for a thinner sheet ,say 60mm rather than 110 or 120mm, will the thinner sheet be effective.I think I read somewhere that it's better to have a thinner sheet than I thicker one but I don't know if that's correct.I haven't the knowledge to work out the thermal values.My budget is limited so obviously I want to buy the most suitable thickness. Of course each individual section will have to be cut to fit and wedged in place and possibly also kept secure with the clips mentioned in the Cleotex literature or with thin battens pinned to the joists.The insulation will be done i the cellar. Thanks.Estelle
tony
3 Feb 2010, 3:42 PM
If it was mine I would use 150mm quilt and staple strawberry netting to the joists to hold it in place.
The theoretical insulation value will be less than the sheet insulation you propose but it is extremely easy to fit it badly and finish up with way less than the theoretical value
I would also add a lot more than 50mm of bat insulation under the joists but you may be OK with 50mm if you can
