Damp coming in around window

pannonica

Hi, I'm trying to find the cause of a damp issue around this window and am looking for some advice. It's a Victorian ground floor flat and I've been here for a year and a half. I noticed a few weeks ago that there were some brown damp patches on the walls. It feels slightly damp to the touch and it's also a bit flakey/powdery. The trim for the flooring is also swollen quite badly, suggesting there have been damp issues in the past (it's not damp now).

Now I'm just in the process of decorating the room and as I removed some of the old caulk I noticed one of the window sills was noticeably damp underneath the old caulk and paint. You can see the darker colour of the window sill in the damp part.

I'm trying to think about what could be causing this. There is a bit of cracked render in the outside wall underneath the bay window, and there are also some cracked exterior seals on the window (they've gone completely brittle). I am actually getting the gutters cleaned next week (they're leaking badly at another part of the house) so if that's contributing to it that'll be fixed soon.

So I guess all of these could potentially be causes, I'm just trying to work out what's most likely to be the main issue and check I'm not missing anything.

I'm also now wondering whether I should go ahead with my repainting and recaulking or whether that would essentially be sealing in that moisture. Also not sure whether I should be using particular types of paint and caulk, I've read that non-breathable materials can worsen damp issues in older buildings?

FreeBear

I see several issues that could be the cause of the damp coming through.

First, a big crack in the stone sill - That needs a repair. Something like Toupret exterior filler should work.

The mastic around the frames, particularly along the bottom is cracked & shrinking - This should be raked out and new sealant applied.

Some of the rubber seals have deteriorated - These need replacing. A window doctor should be able to help on this (and reapplying frame sealant).

Cracks in the render - Again. fill with something like Toupret. But the vertical crack on the right hand side of the bay could suggest a more serious problem (structural movement perhaps).

The concrete hard up against the wall - Depending on where the DPC is, this could allow rain to splash up and soak the lower part of the wall. Ideally, it wants cutting back about 200mm and some gravel put in its place.

The downpipe needs extending away from the wall so that the shoe isn't discharging straight on to the concrete. There also appears to be a hole in the concrete just behind it. If rain water is draining away into the void, it could result in localised subsidence as well as damp internally.

The render - Aside from the cracks, it appears to be covering the DPC. This isn't good...

As this is a flat, you should check the lease to see who is responsible for repairs externally. You may need the freeholder's permission before digging out the concrete.

pannonica

Okay thanks for that, that's helpful. Sounds like there's a lot needing done!

I can probably deal with filling the cracks and replacing the mastic myself. I'll contact the window people I usually use and see if they can do the rubber seals.

As for the render and the concrete, they seem a bit more tricky. Apart from anything else, the management company who manage the freehold are an absolute nightmare to deal with so I'd definitely like to avoid having to involve them as far as possible.

You're right about the hole next to the downpipe (better picture below). Maybe I can do something about this at least. Extending the downpipe seems like a simpler job than replacing the render and digging out the concrete.

Beeboo23

I had a similar issue caused by a leaking gutter. Observe when it’s raining. The gutter was sealed. Let it dry out, repainted and all is fine on our end now. 

FreeBear

pannonica said: You're right about the hole next to the downpipe (better picture below). Maybe I can do something about this at least. Extending the downpipe seems like a simpler job than replacing the render and digging out the concrete.

Shove a short length of downpipe in to the shoe at the bottom - Even 300mm will help keep the water away from the wall. If a section of pipe won't fit in to the shoe, you'll need to purchase a 92.5° bend.

As for the void - It needs a closer look to see how deep it is, and also the extent. Hopefully, it is just the depth of the concrete, so can be ignored in the short term.

pannonica

Beeboo23 said:

I had a similar issue caused by a leaking gutter. Observe when it’s raining. The gutter was sealed. Let it dry out, repainted and all is fine on our end now. 

Yeah, at the moment I'm thinking to get the gutters dealt with (was booked in anyway), fill the cracks in the window sill,  replace the rubber seals, look at the downpipe and then keep an eye on the situation. Hopefully that'll solve it, if not I can think about taking more drastic measures or getting a full on damp survey.

pannonica

FreeBear said:

pannonica said: You're right about the hole next to the downpipe (better picture below). Maybe I can do something about this at least. Extending the downpipe seems like a simpler job than replacing the render and digging out the concrete.

Shove a short length of downpipe in to the shoe at the bottom - Even 300mm will help keep the water away from the wall. If a section of pipe won't fit in to the shoe, you'll need to purchase a 92.5° bend.

As for the void - It needs a closer look to see how deep it is, and also the extent. Hopefully, it is just the depth of the concrete, so can be ignored in the short term.

Okay, great. I'll look into doing that, seems easy enough.

The hole isn't deep, doesn't go past the level of the concrete.