Damp

mezzyd

I have a 1930’s semi which had a single storey extension for a new kitchen added at the back in 2016. This year the wall where the extension joins the old house has become visibly very damp, up to quite a high level.

So far I have had 3 reports from damp surveyors: 1 & 3 pointed to a leaking joint under the sink, which had made the new solid floor wet & said the moisture had wicked up the wall. There is mould growing on the wall behind the sink. 1 said we need replastering, 2 & 3 said we need a chemically injected damp proof course as well as replastering.

This week I have discovered that the biggest cause of the problem is an overflow of water from the boiler as the pressure relief pipe from the existing seems to have been cut off & plastered over instead of being rerouted out to the side when the extension was built. The boiler has a fault which is causing the pressure to keep rising & therefore overflowing down the wall behind the plaster - this has probably been happening intermittently for months, but this week has shown up due to the heating being turned on & water observed running down the front of the plaster & causing the fuse to trip when it met a plug.

As none of the surveyors picked up the biggest cause of the problem, I’m not sure whether to place any faith in their reports & not sure who to consult next. I think the wall must be completely saturated from the look of it & want to be sure that the correct remedial action is taken, rather than make everything worse.

Any advice much appreciated!

Doozergirl

You're right not to trust them.

I'd probably get my gas engineer out to look at it and allow him to drill into the wall (or whatever needs to be done) to fix and divert the pipe.

Once it's fixed, let everything dry out. Maybe put a dehumidifier in. If you can bring the units away from the wall for a while, that would help it dry out.

See how the plaster work is once it's dry. It may need full re-plastering, it may not, it depends on the damage.


See what utter rubbish the people are who say you need an injected damp course? That's what they sell, they have no incentive to find the genuine cause of issues which are most usually cheap fixes.

Their suggestion would have done absolutely nothing . I brt if you called them again and told them what it was they'd still say you needed one for some BS reason.

G_M

Once you remove the source of the damp, whether that is the boiler and/or the sink leak, the wall will (in time) dry out. No need to do anything else to prevent damp in future (eg dpc, chemicals etc) - before the leak there was no damp right?


Of course the damp may have caused damage to the plaster which drying out does not sole, so some re-plastering may be required, but for now just focus on sorting out the source.

mezzyd

Thanks for the advice both, really helpful.

I have an engineer rerouting the pressure relief pipe right now & will let the wall dry out as you suggest, before seeing what else is needed.

The wall is painted with kitchen paint - would it be a good idea to scrape this off, in case it’s trapping the moisture instead of letting it evaporate?

Thanks again.

Doozergirl

Yes, good idea.

mezzyd

Thanks for previous advice; the wall has dried out quite well & the plaster not looking too bad, but there are brown stains on the corners which look as though the angle beads may have rusted. Can you give any advice about the best way of dealing with this? Would it be enough to skim over the walls & paint or is the rust going to bleed through?

shortcrust

mezzyd wrote: »

I have a 1930’s semi which had a single storey extension for a new kitchen added at the back in 2016. This year the wall where the extension joins the old house has become visibly very damp, up to quite a high level.

So far I have had 3 reports from damp surveyors: 1 & 3 pointed to a leaking joint under the sink, which had made the new solid floor wet & said the moisture had wicked up the wall. There is mould growing on the wall behind the sink. 1 said we need replastering, 2 & 3 said we need a chemically injected damp proof course as well as replastering.

This week I have discovered that the biggest cause of the problem is an overflow of water from the boiler as the pressure relief pipe from the existing seems to have been cut off & plastered over instead of being rerouted out to the side when the extension was built. The boiler has a fault which is causing the pressure to keep rising & therefore overflowing down the wall behind the plaster - this has probably been happening intermittently for months, but this week has shown up due to the heating being turned on & water observed running down the front of the plaster & causing the fuse to trip when it met a plug.

As none of the surveyors picked up the biggest cause of the problem, I’m not sure whether to place any faith in their reports & not sure who to consult next. I think the wall must be completely saturated from the look of it & want to be sure that the correct remedial action is taken, rather than make everything worse.

Any advice much appreciated!

That seems almost criminal to me. Gutters overflowing? Chemical injection’ll sort that. Cracked drain? Yeah, chemical injection!:mad:

MX5huggy

mezzyd wrote: »

Thanks for previous advice; the wall has dried out quite well & the plaster not looking too bad, but there are brown stains on the corners which look as though the angle beads may have rusted. Can you give any advice about the best way of dealing with this? Would it be enough to skim over the walls & paint or is the rust going to bleed through?

If the walls need skimming hack out the old bead and use new, if they are ok paint the bead with and oil based paint to seal and then your preferred paint.

FreeBear

mezzyd wrote: »

Would it be enough to skim over the walls & paint or is the rust going to bleed through?

I had a problem with water getting in from a flat roof and causing corner beads to rust. The plaster in the affected area was starting to turn to mush, so bit the bullet and ripped the beads out. Rebuilt the problem corners with bonding plaster and then added plastic corner beads before applying a finishing coat. Whilst a lot of effort, I will never have rust stains showing through again.