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Damp Proofing Question
Damp where chimney removed, and behind k rended wall
We are spending a fortune trying to eradicate damp from a house we bought ... It's about a hundred years old. We had rising damp in a couple of rooms which was professionally treated. Among other things we have rebuilt a chimney that was causing damp in the bedroom below. We replaced various windows as damp was occurring near them and have replastered pertty much throughout.
We re rendered the front of the house with KRend a few months ago and are re rendering two other walls with KRend but problems are already recurring behind the KRend'ed wall following recent rain after the very dry summer.
There was a fireplace in the hall, which has been blocked off and the stack removed, roof retiled. The rear wall of the the flue is in the front room and this is damp in various places.
Getting very fed up .., advice please!
The problems with old houses are they are built with lime mortar. This allows them to breathe, the internal walls are usually lime plaster this again allows the walls to breathe.
Modern materials and older materials do not generally work to well together, anything that stops the walls breathing like cement based products tend to keep the water in the wall rather than allow it to escape naturally.
If the outside walls have been repointed with cement, this can allow water to get trapped in the wall, as there is no cavity, it will allow water transfer from the external to the internal walls.
Would have re-pointed it with a lime mortar rather than a render or if render was a must, would have used a lime render as any water getting in behind the render will now be trapped in the wall and must come out somewhere.
Most older materials are still available although more expensive, getting someone who knows how to apply them might be a tad harder to find.
Lime mortar is 3.5 or above hydralic lime with no additives or cement, it is not hydrated lime which can be purchased at any builder/diy merchants.
Without looking at the issues it is not really possible to say if you actually did have rising damp as it is misdiagnoised in over 70% of cases and seldom works in solid brick buildings.
Good luck Alex
Answered 7th Oct 2013
Im sorry to say but the krend will just make it worst, you must use a lime based render to allow the walls to breathe
Answered 13th Oct 2013