Mineral wool or polystryene for cavity walls

[Andy Dingley]

Waterlogged polystyrene foam doesn't have _much_ water in it. It will still float. However it would now make an excellent heat leak if you expected it to still be an insulator.

[Martin Angove]

Except that according to our surveyor (actually a friend who is an NHBC inspector etc.) and our builders (who did some extensive work for us including removing a chimney brest) our floor is concrete on hardcore (of some description, probably ash) on earth. Probably no DPC at all. In fact surveyor friend said that if it were his house the first thing he'd do would be to dig up the floor and re-lay it with DPC and insulation.

No soffits; eaves are open around most of the roof.

Hmmm... whatever.

Reckon I'm going to have to get quotes from a couple of companies and see if they differ in their survey :-/

Spoke to man from the council who expressed surprise when I told him that neighbouring houses appeared to have had external insulation applied (these are all ex-council BTW). He told me another interesting thing though, apparenly the council only approves mineral fibre or polystyrene; nothing else (for retrofit applications anyway).

Hwyl!

M.

[bigcat]

Silly lad, they use marine grade for that, which is closed cell. Same for those float boards kids use in pools.

NT

[Chris Bacon]

Erm, it's too late for April Fools, try again next year.

[Pete C]

Hello Mr Pot, meet Mr Kettle....

The beads are closed cell, but not the spaces in between. Floats don't use beads, and with good reason, but nothing to do with flotation!!!

cheers, Pete.

[Bob Smith (UK)]

Yes.

The reply by BigWallop included a link to a site detailing the 3 main types of insulation. It says all 3 types do not conduct water, although they are not vapour barriers.

Bob

[Bob Smith (UK)]

Thanks for the link. It seems all 3 types have much the same qualities, and the same insulation value, with each having one unique quality (UF foam makes formaldehyde, EPS balls blow into the loft and must be cleared up). I read somewhere the blown mineral fibres have to be treated to stop damp conduction. I can imagine it will settle over time as well.

Bob