Cavity insulation Foam or Bead?

Shefwedfan wrote: »

Ok so renovating a property. There is 2 sections, older part build around 1980 which has 70mm cavity and nothing in it. Newer section which was built circa 2005 and has cavity. Just found this out from drilling into wall. No idea of size and if current insulation installed. The wall width is 370mm which seems large

I have talked to a few companies and all have said beads! but then they only supply beads. I got a guy out just to have a look, BER cert guy and he said I should try and go foam.

Talked to company that does bead & foam and they said bead is best if nothing in cavity and pre 1985 build. So to say I am completely lost is understatement.

On the older section I am also putting insulated slabs on all the walls and ceiling(bungalow) as well as topping up the whole house with 200mm of attic insulation. Newer section I am not going to at the moment but will do as I renovate each section.

Just wondering does anyone know which is better? There is not much in the cost between foam and bead

If the 370mm wall is block built, might one of the leaves have the blocks laid on the flat? You should be able to figure this out by some careful drilling, you'll feel when the bit breaks through. Just measure the depth drilled from each side. Might need to get a longer SDS bit. You should also be able to figure if insulation is fitted to the inside of the inner leaf. Again just drill a hole of sufficient size and examine the edges. Or poke in some form of hooked wire and drag it around - should be 60mm of insulation board there I think if the job was done properly.

You'll sure have a 'belt & braces' solution if you insulate the cavity and also install insulated slabs!

Edited to add: there is a reason for the cavity in a cavity wall, other than as a space for insulation. Water that penetrates the outer leaf should be able to dribble down to the base of the cavity, without crossing it. The cavity exists to keep the inner leaf dry. So always bear this in mind when filling a cavity.