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Damp Proofing

Treating a damp wall after damp proofing external walls and inside walls replastered

A 3 bed semi-detached house had a ground floor bathroom that was not ventilated properly and had a broken sealant round the bath. The walls were damp and soaked. This was in January 2014. I had a specialist in, who recommended to damp proof the external walls. In the inside walls the plaster was removed and re-plastered.

Eight months down, the wall still feels damp and the bedroom upstairs the bath has the walls damp. I am not sure how this is getting damp or what to do to fix the problem. The exterior is pebble dash render.

Any suggestions or advise?


The property was built in 1935 so about 80 years. The survey report says block cavity render but looks more like just bricks with thick plaster.

Hi. No work was done to the outside pebbledash. I now have mould appearing again on the inside wall

5 Answers from MyBuilder Damp Proofing Specialists

Best Answer

how old is the property. what type of property is it, cavity walls or solid brick?


could be felt at the gutter line eroded,cracks in the render,outside ground level to high, cavity full of rubbish.


Answered 9th Sep 2014

from the age of the property there could not be any cavity it would need injection then re-plaster.


Answered 5th May 2016


You mentioned it was suggested to damp proof the exterior walls, you then go onto in more detail sorting the plaster on the inside. You then finish with the exterior is pebbledash. Can you confirm what it was (if anything) you had done to the outside of the walls of the property? Was it just internal work?


Answered 25th Oct 2016

Many things would have to be taken into consideration, firstly moisture readings can be taken to identify problematic areas within the bathroom. Check to see if the dpc has been breached or damaged in some way, whether there is a cavity and if the cavity has been bridged allowing moisture to migrate; and if any air bricks are installed and to see if they have been blocked. Plus another factor would be to have a fan fitted and to check that the correct air flow allows to take the moisture out. Internal and external readings would be taken to ascertain the level of moisture within the bathroom to make sure the readings are in line with BS5250:2002 this is industry recognised. If there is a problem within various forms of damp proofing can be undertaken to rectify the problem. This can be in a form of either damp proof injection, membranes and damp proof plasters on the interior you can also treat the exterior in a similar method.


Answered 5th Jan 2018

There's been no comment of ventilation. As property this age most people moving in don't like the ventilation that's there as to draughty and block up or remove.
Could you highlight of ventilation.
Kitchen areas. .


Answered 31st Mar 2018

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