Damp at base of wall

Woodingdeany

We live in a 1930’s semi detached outside Brighton andover the past few years we have experienced an area of damp at the bottom corners of our rear patio windows – South facing. Another has now appeared at theother side of the doors. The property is at the top of a hill and exposed.

Looking under the floorboards itseems that the problem is spreading onto one of our joists and this is worryingus.

So far we’ve had the glaziers out to remove the doors,reseal and replace to no effect. We also had the rear of the house re-renderedlast year, this coincided with the problem spreading to the other side of thedoor, but of course this could be a coincidence.

There is a patio to the rear, the level of which is higher than the DPC (I know).
One quote has advised removing the rockwool insulation and another hacking off the inner plaster, fitting a membrane and then replastering effectively trapping the problem in the wall. Both have advised fitting additional air bricks.

Should I go for one, a mixture of both or neither solution?

smallfry27

I thought I would respond out of empathy rather than any real ability to help. I also have 1930s house in Hampshire with ongoing damp problem. My DPC is only 2 inches above ground. Like you I had someone advise me to treat the inner wall, in my case by an injected sealant. He was going to charge me several hundreds of pounds but wouldn't guarantee it would fix the problem, so I said no.

I was also told that rubble or insulation settling in the cavity can provide a bridge for water to cross from outer to inner wall so I did have this checked and cleared - it seemed to help. The same builder raised the air bricks as he thought the water could be entering through them. The current problem is beyond the area that was cleared.

Recently I have been advised to try Thompson seal on the outside of the wall. To my purely amateur brain it seems more logical to try and stop the water on the outside. Perhaps the danger is that some water will penetrate above whatever level you treat and will then have no way to escape.

Are you able to take out a channel along the edge of the patio so it is not in direct contact with the wall ? Then perhaps you could waterproof the lower levels of the wall ? I guess we both need more expert advice - and a guarantee that any expensive job will actually work.

Good luck !