Damp on pre1900s property, solid walls, areas below ground. Also rendered gable end wall damp.
Anonymous user 23/02/2024 - 3.17 PM
Just bought a cottage which is 1850s old. The walls are solid stone about 500mm thick. The ground floor is about 12 inch below external level on back wall. There is damp on this wall at low level. Externally they have created a solid concrete path right up against the house which has lifted the ground to this level. And the garden rises steeply away from this path. What would be a solution to try to eliminate damp?
Also the South facing gable end wall has damp both upstairs and down, which they have remastered internally. This gable end has been fully rendered with sand and cement, which looks to have been done a couple of decades ago. What is this solution here? Removing rendered and repointing? If so how is the render best removed? Thanks for any help!
Are you a tradesperson and able to answer this question?
Easy.
In respect of your first paragraph. Remove the concrete path and get external ground level to below internal floor level. The original stone and lime mortar construction will be allowed to breath and the damp will disappear. You can then reinstate the path and build a retaining wall for the garden. Best build that wall from traditional brick or stone and lime mortar. Please check that the internal wall is correctly plastered in lime.
The gable end must have all and any cement render removed. Render should be removed manually with hammer and chisel to minimise damage to the original brick or stone work. In the majority of cases the render will come off easily as cement struggles to stick to lime mortars and stone. It can however damage old brick surfaces. Without analysis of the stone type and running a patch test/survey it is hard to advise on the result. Be aware the renderer may have used a chicken wire mesh to help stick it on.
Hopefully the render hasn't caused too much damage to the original wall. When done make sure the internal wall is correctly plastered in lime and external ground levels are lowered.
Make sure fireplaces are opened or properly vented. (Wood burner flues tend to be insulated and this not good news for the chimney brickwork!).
You will now have a dry and healthy house. If you need to repaint then my recommendation is a china clay based paint such as Earthborn.
Finally check all guttering and downpipes for leaks in order to eliminate any splashback.
Hopefully the roof is sound as you did not mention it.
This is an easy job that just involves a lot of reverse building, digging, blood sweat and maybe some tears!
That's it . Your house should now be in perfect order
Best of luck and thankyou for saving our heritage housing stock.
With out looking at the property the answer is difficult, but you should never render in sand and cement, it will never breathe you must re-move and after a period of time after the wall has time to breathe and dry render in lime and only lime. French drains could be the answer to the external damp, the internal damp will need a site inspection to investigate the damp and type of plaster used. Without photographs it is hard to come to the correct method of revolving this issue.
Kind regards Geoff Guildford
