Case study
Cammeray: The Injection Worked, the Render Did Not
The Property
A freshly renovated bungalow in Cammeray. New paint, new skirting boards and new floorboards, and rising damp in the walls. It was early 2020, in the middle of months of very heavy rain.
At the quote I recommended injection and removing the salt-damaged render. The owners declined the render removal because they were about to move in.
What Happened
We did the injection and the builder refitted the skirting boards. About six months later, during more rain, the owners called to say the injection had not worked. The walls looked wet.
I had told them at the quote that this would probably happen if the render stayed on, and I went back to show them why.
What was causing it
The new damp course was doing its job. The water was coming from the salt left in the old render. Salt pulls moisture out of humid air. In wet weather the salt in the render soaked up enough water to make the wall sweat, even with no water rising from the ground.
Why render removal is part of the job:
- Injection stops new water rising into the wall
- It does not remove salt already in the render or plaster
- Salt keeps drawing moisture from the air in humid weather
- Salt-loaded render needs to come off to roughly a metre or more
- Replace it with a salt resistant render once the wall dries
The lesson
If your walls still look damp after treatment, it is often the salt, not the damp course. That is why my quotes include render removal and a salt resistant render.