Damp after Cavity Wall insulation removal

clearskys

HI I had cavity wall insulation (rock wool) removed due to damp on internal walls - all along base of the hall -which worsened when it rained . My surveyor advised the retro fittred cavity wall insultation was responsible as outside wall was sited to suffer wind driven rain. I bought the house with the problem and contacted the installers to remove under the CIGA guarantee. They agreed to remove as a good will gesture stating the insulation was not cause of damp but the wind driven rain and porous render would have been too much for the insulation and broke it down. Though inspector later advised me the wool that had been used was no longer used as it holds water, I was just happy just to get it removed. A month ago the team took it out. After a couple of dry weeks damp got much better we had rain and it all came back. I rang them they came up and looked with a camera advised me some wool was still remaining and they come to take it out. . Though the areas of damp did not relate to areas of wool left when i watched them removing it. I thought my damp problems were over and watched the lower walls all dry out again.i usea little water gadget though i know they are not considered very accurate I thought just by the pattern of readings decreasing show it is drying out. All good till we had raing again and walls looking damp again and all readings back up high. Has anyone had insulation removed and faced these issues ? does the damp go i am trying to understand if I should be contacting the insulation company again or exploring other options and considering my surveyor/home buyers report and the supporing damp survey i also obtained had the wrong cause of the damp ? Help anyone ?

Leosmum_3

Hi,

Sorry to hear your bad luck! Trust you have checked the obvious of drains etc, is there bedding plants or any slate tiles that run along the bottom of the external wall?

Would be interested to know the following points before you are defintely are sure it is the cavity wall insulation.

1. What is the room humidity of the hall, if unsure you can pick up a Thermo-Hygrometer on ebay for under £20.00 to constantly measure this, and how does this compare to other rooms downstairs along this external wall.

2. What type of plaster is on the internal hallway wall (if you know).

3. What is the state of the rendering on the external wall.

4. Is there adequate heating / ventilation in this section of the house.

I had a very similar problem, and was told it was the external brickwork, this was not true and the rendering was excellent. I was also told it was the cavity wall insulation (the previous owner had this put in a few years ago - I live in a victorian semi, with one of the earliest forms of cavity wall), again this was not true.

Ultimately it came down to good old fashion condensation in the hall way. The previous owner had moved the front door and fixed it to the front porch, allowing a lot of cold air to hit the hallway, coupled with the fact of a boiling hot radiator on the oposite wall and a lack of ventilation, the hallway room humidity was 78rh, it should have been no higher than about 55!

I also suffered damp patches in the upstairs bedroom directly above the hallway, I had been away for a month, and turned the radiator off in this room, and had rails of clothes against the external wall, in a nutshell the lack of air (due to all the clothes against this wall) and the lack of heating caused these damp patches.

The solution after extensive research and speaking to a historical building expert was to go and measure the room humidity, once I monitored this, kept the temperature constant and ventilated this part of the house the wall dried out instantly!

I had extremely heavy rain last night, and the walls are as dry as a bone.

I am in no way saying that this is the problem that you have, but it is definitely worth following up.

clearskys

Thank you leosmum soz only now got back online . I found your comnents really helpful . My rendering is not fab is a bit blown in places my surveyor insists if cavity empty though won't pass over rain water .dont know what plaster us on the internal wall ?but house has had front door moved to porch like yours so I have just ordered hygrometer you suggested . I'm hoping now that could be it

Coastal_Wall_Ties

Hi I was wondering if your damp problem has been resolved yet?

Your problem sounds like it could be debris in the cavity breaching the damp course. We often find that cavities have a lot of rubble and like your surveyor mentioned as long as the cavity is clear this will stop rain penetrating through to your internal walls. If it drys out and returns when it rains I could guarantee its not a condensation issue.

Don't waste money on damp injection, a good local builder should be able to clear below the damp course for you. If your anywhere near the south coast I would offer our services.

All the best.