Insulation Kingspan v celotex

[carrollm]

Hi can anyone tell me - are they the same thing ie just as good as each other?

Also if you are insulating a loft extension and you use regular yellow wooly insulation (I don't know what it's called!) in the walls is it as good as celotex - can you mix and match - and can you reuse old yellow insulation?

thanks!

 

[mointainwalker]

They are the same material.

Fibrewool/rockwool insulates about 40% less well than these materials for same thickness. It can be re-used.

There are no problem using any insulating materials with any others

You can see how well any insulation performs by checking on its U/R values in the specification.

 

[carrollm]

Thanks Mountainwalker - which mountains? Plse could you also tell me - is it true that you should use celotex on the dormer where there is no outside brick wall but that you can just use the fibreglass wool in the bits where the outside is brick or thermal blocks (ie the raised gable end or original building).

many thanks

 

[mointainwalker]

N Alps/Tarantaise

Insulation is insulation. Broadly speaking you can use anything anywhere until you start to take into account things like compressibility, fire-risk and others.

When working in roof-spaces it may be that it is much easier to fix rigid boards in position than either floppy rolls or batts and so, at a financial cost , the easier way is often preferred.

The most important thing to note when insulating is that you must have a vapour-barrier (can be just a poly-sheet) on the warm side i.e. room-side of the insulation. This prevents warm, moist air from the house passing through/around the insulation and then condensing when meeting air cooled by the cold outside wall. This may be why you have read something about especially using celotex in the dormer.

Because this material is impervious to water-vapour it provides a vapour-barrier itself without the need for the poly-sheet, but you then have to take care to tape all the joints with good quality tape to make a complete seal.