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Damp spots on dry lined wall

Postby jwoo75 » Sat Sep 13, 2008 11:09 am


Our cottage is built mid 1800's so may be lacking in some of the more modern damp treatments so hopefully you can help.

About five years about the cottage was renovated by the previous owner. This (wet) summer, I've been noticing random damp spots on the downstairs walls. I know in the renovation that the walls where dry lined so I was wondering if the damp spots are where the adhesive is attaching the plasterboards to the wall?

Some spots are low down by skirting, some are half way up the wall, some are on external walls, some are on internals walls and some are on the wall adjoining the neighbours house.

The spots are not growing any mould, they just appear as dark circles or rings. Some along the skirting are in patches up to ten inches from the skirting upwards but it is not consistant.

Any help, guidance or suggestions would be greatly appreciated. One final point - if any works need to be carried out, is this something that can normally be claimed on the house insurance?

Thanks for your help.

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Simply Build It

Postby Perry525 » Sun Sep 14, 2008 5:33 pm

It is unlikely that a house built then will have a damp course.
So from the time they started building it till now it has always been damp.
It will have rising damp from the ground.
Damp walls from the rain.
Damp walls from the water vapour you put in to it during your everyday living.
The way the house was designed, all these factors would have been taken into account.
And the open fires, badly fitted windows and doors would have kept it dry enough.
Someone has changed its design, probably blocking holes, making cosmetic changes that have affected its ability to dry itself, probably in an attempt to get rid of drafts and make it warmer and more modern looking.
The best thing is to restore its original charm by ripping out the plasterboard and changing it back.
Naturally you want to be warm but, unless it is brick, fitting a damp pfoof course is almost impossible, if it is brick then a chemical cream injected dpc will work.
But, chimneys are very difficult to deal with as you can never tell how they were built and there are often bits that almost impossible to reach. (They tend to be a weak spot.)
If you can fix the rising damp, then painting all the exterior with silicon water repellent paint, will solve the damp coming through the walls.
Then there is the question of man made damp.
Installing extractor fans in the bathroom and kitchen will move that water vapour outside.
And finally, buying and using a de-humidifier or two will remove the damp caused by breathing sweating etc.
Keep bathroom and kitchen doors closed.
Do not dry things on radiators.
That will do it.
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Postby thedoctor » Sun Sep 14, 2008 5:49 pm

See any of our projects on Damp and read through the series. It will take everything into account including cold spots caused by bridging insulation. If you still need help, click through to the sponsors of the projects, PR Systems and they will give you free, no obligation advice either by email or telephone.
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Postby stuart C » Sun Sep 14, 2008 8:55 pm

A friend of mine is a damp specialist and he showed me a photo of an old property that had exactly the same problem. It was caused by salts in the old walls going through the adhesive and into the boards. As these salts were hydroscopic they attracted condensation and left round marks on the walls. They had to rip off the boards and render with a salt retarder in the mix.
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