Cavity wall insulation removal

meropenem

Hi, I've just had a building survey completed on a 2 storey 3 bed semi detached house. It picked up some minor damp issues and suggests that the cavity wall insulation should be removed. 

After having done some reading on the issue, it appears that wall insulation causes a lot of problems in the old houses. 

Does anyone have experience of doing this and the rough costs involved? Is this something I could negotiate a lower price on the house?

FreeBear

Depends on the type of insulation. For all types of insulation, some bricks will need to be removed close to the bottom of the wall.

For polystyrene beads, it is relatively easy to suck them out with a real big industrial vacuum cleaner type machine. Fibreglass/rockwool can also be sucked out, but may need some rods inserted to break up any intransigent lumps.

Expanded foam, forget it - There is no easy way to break the stuff up and get all of it out of a cavity.

Homer_home

Before you go pulling bricks out if walls, is it certain the insulation is causing these issues?

There are many many ways damp can get in or be caused by bad practises inside the house , what and where has the survey picked up and what does it mean by minor?

meropenem

This is what the report said:
It is the opinion of the writer that older properties (such as this) are not well suited to cavity wall insulation. The masonry and mortar tend to be porous. Some moisture ingress into the wall cavities is therefore likely.

The following moisture levels were noted:

1. In the hall, to the left wall. 12% saturation.

2. In the hall, to the right wall. 14% saturation.

3. In the lounge, do the front wall. 10% saturation.

4. In the lounge, to the left wall (to the exposed brick cladding). 14% saturation.

5. In the lounge, to the right wall. 12% saturation.

6. In the rear reception room, to the right wall. 14% saturation.

7. In the rear reception room, around the fireplace. 12% saturation.

8. To the wall between the staircase and the rear reception room. 14% saturation

9. In the rear reception room, to the rea wall. 30% saturation.

10. In the rear outrigger (kitchen), to the right wall. 14% saturation.

11. In the rear outrigger (kitchen), to the left wall. 25% saturation.

The higher damp readings to the external walls may be caused by a buildup of debris in the wall cavities. As discussed earlier, the retrospective cavity wall insulation may also be contributing to the problem. We would recommend that the cavities of external walls are cleaned by removing external bricks (or airbricks), removing debris (and possibly the cavity wall insulation) to below the height of the damp proof course, and then re-instating the masonry. It may be prudent to install additional airbricks (to ventilate the void under the floor) at the same time. Condition Rating 3.

Homer_home

I'm assuming he used a moisture meter ? 🙄

floppydisk1

As homer_home  said - if that " surveyor " used battery operated 2 prong " damp / moisture  meter " next time you might as well offer him to use your chocolate teapot , in fact that would be probably more useful with more accurate readings. 

meropenem

Yeah the more I look at the report, the more I think he’s just covering his back and a different surveyor could have a totally different opinion.

I may just leave the insulation, seems to have been put in more than 10 years ago and house seems ok. No visible signs of damp when I went. Also house has been vacant for about 6 months.

EssexExile

Wait and see is the best option. I don't know what age your "older" house is but we had cavity wall insulation put in our 1950 house many years ago and it hasn't caused any problems.

twopenny

I had cavity wall insulation put in a 1920's house. No problems with damp other than old houses have more moisture in the walls through age.

The surveyor did say there was damp in the plaster but that it was commensurate with the age of the building ie this happens with time.

Older houses should be ventitlated ie open the windows regularly, heat properly.

One time when I was stoney broke I only had the heating on in the rooms I was using. I did get light signs of damp after a long winter and was a lesson learned and kept it low everywhere.

The other thing I noticed after having the insulation was where it would be warm inside on a sunny winters day, it wasn't. It kept the heat in from radiators but didn't allow the sun to warm the walls of the house and I ended up having the heating on more. So I didn't come off any better.