Exterior wall insultion

briano mc

advice needed, is there such thing as a pumpable insultion for exterior walls. extension, not well insulated, not able to get to sides due to neighbours extension, would love to fill all the gaps and stop the gales blowing through!!!

Builderfromhell

How are the existing walls built?
If they are cavity walls then bead insulation can be pumped in. Exterior of wall should not be brick or stone.

briano mc

the walls are built with breeze blocks!!

MicktheMan

briano mc wrote: »

advice needed, is there such thing as a pumpable insultion for exterior walls. extension, not well insulated, not able to get to sides due to neighbours extension, would love to fill all the gaps and stop the gales blowing through!!!

Insulation will not stop "the gales blowing through"! Don't mix up insulation with air tightness (many do).

If there are insulation issues as well as airtightness, then an approach which tackles both issues should be sought.

briano mc

if it lack of air tightness then are there any suggestions?

MicktheMan

What is the exact makeup of the exterior wall including internal finish? If there are gales blowing through then do you know where the air is getting in? Are the walls double leaf cavity walls or single leaf cavity block? Give as much detail as you can/know.

briano mc

as far as i know its a single cavity block with kingspan insuation board, about an inch and a half thick, the problem with filling the cavity blocks would be that there would not be enough room to get down to drill holes to pump the insultation in.
as is clear i am far from an expert .
thanks for the advice so far

MicktheMan

First a note on pumping insulation into a cavity block wall. In my experience pumping insulation into a cavity wall has little to no insulation effectiveness (i.e. retarding the flow of heat to the outside) This is due to the huge number of thermal bridging points in the wall.
However, I do not know what the impact on airtightness is. Perhaps someone else on the forum may have experience in this (i.e. pre and post pumped insulation air tightness test results).

The solution to your problem depends on your budget etc and it is dfficult to give a precise solution without a proper survey for airtightness.

One method of improving significantly the airtightness of your block wall is to apply a sand/cement plaster to the interior side of the exterior walls as block in themselves are not airtight and the sand/cement seals them.
You say that the interior finish is rigid kingspan/plasterboard. This would require the removal/replacement of this insulation/board. If doing this then you must be mindful of the need for a ventilation gap at the back of the insulation to help prevent mildew/mould growth if using the non-breathable type insulation. You could at this stage opt for other types of suitable breathable insulation which reduces the need for the air gap.