Had free cavity wall insulation done and now have damp patches!

mignon_2

Hello,

all advice welcome here please. We signed up to a new energy company who encouraged us to get cavity wall insulation done. I'd always thought we couldn't as the house dates back to the 1890's. However, we do have cavity walls, and thought, why not.

Not overall thrilled with the job, lovely old ventilation bricks were remved and replaced with plastic ones, and obviously holes in the house patched up, however, I will put up with these to use less energy and be warmer.

HOWEVER, when I left for work yesterday morning, I noticed a large damp patch on the outside wall, mid way up the wall. As soon as I googled this I noticed that people were getting damp patches after getting cavity wall insulation.

It is in the middle of the wall, so is not rising damp, there is not damp inside, an no burst pipes. The insulation is black polystyrene balls (carbon I think). It has only appeared, and at the moment just looks like a wet wall, but I am obviously terrified of getting damp!

Any experience or advice?

Many Thanks!!

paulmapp8306

Damp patches can occur with cavety wall insulation. From what I understand its because there is no gurentee all the gap is filled. There are lots of bits that get into the caveties - bits of building material - wood etc, and as your retro filling it doesnt always reach all the gap.

What happens then is a temp difference between the insulated and uninsulated part of the wall - which leads to condensation (internally) which shows as damp patches (can appear inside or out).

Quite what long term effects this can have I dont know.

the other possibility with the ball filling (rather than the wool filling) is that if filled too full, damp can get into the wall (if there is heavy rain and a big enough wind to drive the rain into the wall) which then seeps through the insulation material like a capilary. This doesnt happen with the wool type material (or at least as often or as severe).

Hopefully someone else can give some more definate information on cause, potential longer term issues, and rectification.

mignon_2

ah. As I thought. Hmm. I wish i'd looked into this before hand. It's right next to our front door so very obvious, and clearly damp will do no good for anyone!

Thank you.