Damp exterior wall

[guitarust007]

Hi all, I have a room with some damp issues which I don’t think are connected. The first is damp under the windowsill on an exterior wall. House is 250 years old, no DPC. Externally house is cement rendered. Think damp has originated from outside flower bed which has now been addressed with French drain and lowering of ground level plus repointing.
Plaster has internally been removed, see photos. I have two questions a) the brick work seems a mess - is this something that needs fixing or is it fine to just replaster over b) what would be best to replaster with? I assume lime but as the external is rendered, is this still going to be the best approach? Is there anything by else that might be more cost effective? I am cautious spending a lot of money on lime and then ending up with exactly the same issue in X years time….

 

[guitarust007]

Any ideas?!

 

[dannyg]

I am in a similar situation.

My walls are solid stone and rubble walls (500mm) thick. Internal walls are all lime. One external wall was rendered in cement a couple of decades ago. This has caused some damp issues internally basically because moisture gets trapped between the cement render and wall. Over time the walls hold more and more moisture. External lime render allows moisture to pass through it.

I am completely removing the cement render externally. Thankfully it's falling off using an angle grinder and an sds drill. I plan to re-render the wall in lime this spring/summer.

If damp is localised to one area, it may be ok to leave the external render as it is. You mentioned you lowered the ground levels? If this is the case then it may just need time to dry out. I think it takes something like one month to try 1inch thickness of the wall

Some of that brick does look suspect. But in any case I would rake out all that pointing and re point in lime mortar.