Damp proofing

[Me2Me2]

We have a patch of damp - 1ft x 1ft approx. Builder has quoted £420 to fix (sand and cement, treat with chemical agent). Sounds like a lot to me but what do you think? I don't know what is reasonable and am finding a lot of variation on the web
We're in London.

What is the actual cause? You need to establish that first before any treatments are used. What is the age of the house? Chemical treatments are often missold and rarely work IMO. In such a small area all that might do is cause the damp to head elsewhere - path of least resistance.

Not sure of the cause. The house is 1890s terrace. There is a drain pipe running down the outside wall and the damp is low in the corner on the inside of that wall, so I was thinking maybe it had a leak at one point. I don't know anything about this stuff tho

I'd have a good look at the drainpipe in that case- you could observe it when it's raining to check for leaks. If it is that, get that fixed. Dependant on the severity you might need to replaster once the wall has dried out.

If it is the drainpipe and you go ahead with the works anyway, all it is likely to do is displace the problem, costing you more.

You could get another builder around to have a look if you don't feel confident.

Using cement in a building of that age is likely to aggravate any problems rather than cure it.

Thanks. I hadn't considered that but googling damp in victorian houses it sounds like you're right. The damp guy has 100% positive ratings on MyBuilder but all he wanted was a photo for the quote

I've just consulted out building surgery again (moved into the house 4 months ago) and see it recommends another air brick in the front side of the house (there is one in the bay but that's it).

Would air brick plus damp proofing do the trick do you think? (along fixing any leak in the drain pipe). I mean, is damp proofing ever advisable in victorian properties or should I just forget it?

(keen for quick fix, basically)

I'd fix the drain pipe first (if it is the drain pipe), give it a few months to dry out and see if that's the actual problem. You may find that once the cause of the water ingress is removed, then so is the damp patch.

Agree with Grendlesmum - fix the drainpipe and how you go.

Damp proofing not usually advisable, just sort out the source and go from there.

Ps if it was a damp proof company they have a vested interest in selling their products to you. Terrible that they didn't even see it themselves.

If the problem is the drainpipe, there are a few things that it could be (that I can think of)

• the gutter / drainpipe is blocked with dead leaves, etc, and water isn't actually going down it, but is sort of dribbling down the sides
• the drainpipe is cracked and water is dribbling out of it (my personal guess)
• the drainpipe is fine, but the drain itself is blocked, and so nothing is actually draining away
• the 'drain' is actually nothing more than a pipe going into the ground, without any way of taking the water away from the base of the wall (we have had this one - it results in damp walls)

Where is the water that does go down the drain pipe actually going? It could be that it is not draining away properly and causing damp rising up from the ground. I would get a surveyor round to do a proper investigation because none of us has seen it either!

Agree re fixing the drainpipe then waiting a while to see what happens.

I wouldn't touch with a bargepole any damp co that did a quote in the basis of a photo rather than actually looking at the problem in situ.

Right so I've checked and the drain is fine but there is some damage on one of the joins on the drainpipe. Showers forecast tomorrow so will see then if that's the issue. (first time I've been pleased about a bad weather forecast)

Thanks for replies

Just a thought, what is this room used for ? could it be internal damp caused by the family ? damp will form in the cold part where the wall temperature falls below the dew point. is that part of the wall cold ? is the room used daily and heated/ventilated ? what is the external wall coating - render ? do you know if it is a cavity wall ?