Cavity Wall insulation

slim81

Hi All,

Starting to build a house next month and and trying to find out the best way to insuate the cavity wall.

Have read a lot on the net about the pumped insulation, has anyone has any issues with the dampness gettin into the internall walls?

Any information would be apprecaited.

Thanks

Quazzie

I found this to be an interesting read.

Builderfromhell

I read the summary of the Kingspan study and it is worth noting that they surveyed housed insulated with 'mineral wool' pumped insulation. This is rarely if ever used today as it does not fill all cavity. It easily gets stuck on wall ties and or mortar. Most pumped cavity nowadays is done with polystyrene beads with a glue to bind them together once they have settled.

Msmaloney26

The dampness,sag and uncomplete fill issues seem to be worries with pumped insulation systems: bead or rockwool, are these unfounded fears?
I have just seen these type of comments in the many posts on the subject regarding cavity insulation. What do the builders/archs on here recommend?
Stick with tried and tested foil backed systems or pump rockwool/bead into cavity (make cavity slighly wider <150mm?)
Are the rockwool/bead systems becoming more popular due to ease (shall we say) of installation in comparison to foil board systems which may be more intricate to install correctly?
Interested in the area as with the OP and dont mean to hijack.

Retro-Fit

Full fill Cavity is not recommended in the western half of the country, the outer leaf will hold too much moisture. The biggest issue with bead fill is not moisture getting in, but moisture getting out. The main criteria of a cavity walls is keeping the concrete dry. Every house produces over 10l of water vapour per day and you need to stop this getting into the fabric. Post 2008 Part L, the standard cavity is redundant. Its one big cold bridge, the inner leaf sits on an uninsulated rising wall. An inner leaf of Quinn-lite helps. If this is drylined, make sure the drylining is woodwool or sheeps wool which is mould resistant and breathable. Any water in the fabric will dry back into the room.

Anyone building today should consider these option.
1) 215 inner leaf with 100 Polyisocanurate, sealed before erecting outer leaf courses. Drylined inside with sheeps wool and Intello membrane.
2) 250 SIP timber panel with I beam, with woodwool insulated services cavity.
3. 150 EPS with external render on 215 Block.

Again dont get fixated on walls, put your attention into the interface of materials. Design to hold in heat, its going to get very expensive. Unless of course you're planning to sell in the next 5 years, then who cares, just build cavity. Although, The 2010 Part L regs completely change how we build new buildings, you'll be selling a CD player to the ipod generation.

cracked

retro-fit,
i am also beginning a self build - what u say seems on the ball , however any chance u could dumb it all down a bit!??
thanks!