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Damp Proofing

Renovation of 1920 house single brick construction

Anonymous user 28/02/2024 - 3.28 PM

Have experienced very wet wall down chimney breast and damp coming through damp course. The house have been empty for 3 years and roof tiles missing, warped guttering allowing water to fall down the walls. Chimney and stack removed and dehumidifyer running constantly to dry out. Also an extension very close to the wall and some builders rubble can be seen which may well not allow water to drain away. The floor boards are dry. Have had advise so far that I should cement render with salt inhibitor, skim create a stud wall thermal board and plaster. 2nd suggestion use planton membrane, create a stud wall thermal bd and plaster. I have read that houses of this type need to breath so sealing the walls may cause problems later on with trapped moisture. from what I have read these old houses cannot be treated in the someway as modern day build. I suspect that now there is no water coming in then the problem may be solved but still have the ground debris which I cannot get to. Any advise would be appreciated as to the best way forward. do I call in someone who knows about old buildings. where do I start? The internal walls all had polystyrene as a form of insulation which I have removed. I wanted to thermal board the outer walls, but am not sure if this is the right way to go. Would the walls have to be battened to allow breathability between the wall and thermal boards. The out shell of the house has been rendered in an ecotex material. I need to find out what effect this has on the building and what type of paint to use at some point. Any advise please. Thank you

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Rating: 5 out of 5

Mill Hill, London

As it's a 1920's property, no doubt you already know it's constructed from solid common brick. Fireplaces, chimney breasts are a common area to become damp this can be for 3 possible reasons; 1. Chimney pots not capped or flashing around chimney stack is allowing rainwater to ingress. (You've previously stated that the stack has been removed but you have 3 roof tiles missing) Rainwater may be tracking through at high level and using the flue to find its way down. 2. You state that the guttering is warped, allowing rainwater to spill over and cascade down the external brickwork of flank wall. This will no doubt be causing penetrating dampness of rainwater due to the brickwork absorbing this water to saturation and then transferring the moisture to internal surface. (This can happen in varying degrees dependent on condition of brickwork outside and also absorbency of internal plaster. 3. Rising dampness due to chimney breasts and fireplaces not being constructed with a damp proof course (DPC). This was due to it not being required during the time of construction. We'd use the fireplaces, the walls would heat up and dry out naturally. Plus you'll find that even if a slate DPC was fitted during construction, thermal movement (Expansion and contraction) of the brickwork as it warms and cools will cause the slate DPC to crack in sporadic places and allow moisture past. My opinion is that it is most probably caused by penetrating dampness due to bad guttering and my advice would be to ensure that your roof and guttering is fixed as a matter of urgency to prevent further rainwater ingress and penetating dampness. As rainwater is fresh, (not containing hygroscopic salts which can contaminate plaster and brickwork) The area can be allowed to dry naturally without any further intervention on the internal side. I would normally advise against using cavity drain membranes on ground floors as brickwork of this age and construction type needs to breathe freely or you could be trapping residual moisture within it. You should find that once you fix the roof and guttering, you'll see signs of improvement and drying. If this is not the case after 3 months, revert and we can discuss further.

Answered26 April 2017