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Damp in Bedrooms Caused by Water Penetrating Granite?

Postby broadsea » Tue Oct 11, 2016 9:21 am

We have had a problem with damp in the upstairs bedrooms. A surveyor said it was because the water was coming in through the granite, can this happen? If so would I have to use some sort of sealant on the outside. The rooms also have lathe plaster and when I made a hole through the plaster there was a large collection of plaster dist and pieces of plaster behind the skirting boards. I was thinking that this collection of dust would stop the aisr from circulating and helping to dry out the walls. If I clear this out will this help. The damp has been ongoing for more than 1 year. The outside has been completely repointed, slates on roof sorted.
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Postby neil-the-handyman » Thu Oct 13, 2016 12:00 am

Hi Neil the Oxford handyman here.
If the damp is a relatively new situation that has recently made an appearance then it may be one of the following.
Has the repointing been done using lime in the mix? If it hasn't then what happens is the moisture in the traditional lime mortar behind the new pointing becomes trapped and as it can't 'breathe' externally is forced internally.
An added problem this creates is to create different rates of expansion which will over time cause the snots to snap on the lime plaster and thus crumble.
A bigger problem though is caused externally. If the mortar is harder than the natural granite then moisture is forced into it. When winter comes and it freezes it will blow the faces off the traditional stonework.
Or it maybe that you have new windows and have reduced airflow, if this is the case install vents.

Hope this helps,
Kind regards,
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Postby Matt93 » Thu Jan 19, 2017 8:13 am

Yeah my guess is also moisture, mounting ventilation might actually help.
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