spray on insulation

[biff.mcg]

We are buying a house with sprayed on roof insulation stuck to the underside of the roof tiles. How do we get this stuff off? Does anyone recommend using this stuff or are we on a loser here? there are some cracked tiles - is there any way of melting this stuff?

[alan30]

http://www.foam-insulation.co.uk/

Do you need to replace cracked tiles as the web site suggests the foam seal and secures everything?

[qapmoc]

Hi biff.mcg,  I can tell you from experience that this stuff is almost impossible to remove,  the only way to remove these sprayed foams is often to cut off the majority and leave a thin layer.  Why do you want to remove it anyway?

[biff.mcg]

thanks for comments alan qapmoc and eddie.  The cost for replacing the cracked tiles is more expensive because this stuff is there.  Also if water is penetrating and goes unnoticed because it is travelling somewhere else then we may get some timber rot.  Have heard horror stories about this stuff and been advised to replace the whole roof (tiles won't be re-usable) to be on the safe side.  We were considering a loft conversion for this property.

[jake-the-peg]

Don't know whether i's an old building or not but this is from SPAB's website:

Q. Are bitumenised treatments or spray-on foams a good idea?

A. No, experience shows bitumen-coated fabric on the outside of roofs or spray-on coatings underneath can be a false economy, and cases have been reported of serious damage resulting to the structure. Such treatments prevent proper inspection, hinder the re-use of slates or tiles and, by reducing ventilation, increase the risk of timber decay.

So I can quite understand wanting rid of it unfortunately I don't know of any easy way to do so.

I think there are also building regs that require a 50mm ventillation between insulation and roof covering.

If you're going ahead with buying it I'd earmark a substantial fund for dealing with this!

[biff.mcg]

Thanks Jake - I think you are right.

[BillyBB]

I had it on an old house and it was great, immediately noticed better insulation because frost stayed on the roof longer. Never again lost a tile in high wind and the attic was not as dusty.

[biff.mcg]

Thanks BillyBB for your positive feedback, it's good to see the other side of the coin as well.  I think that for this substance to work well, the roof needs to be in absolute pristine condition.  The problems seem to occur when water manages to penetrate.

[chantelo]

Firstly, the sprayed on insulation will not cause your timbers to rot as it is not sprayed onto all 4 sides of the timber.

Secondly, beyond 3 inches the sprayed on insulation wii not even allow water vapour to pass through, due to it's closed cell structure.

Thirdly, read the alternative approach in part L of the building regulations, as it is not necessary with all materials to leave a 50 mm airgap.