Oh sh*t damp patch

[Janblues]

Noticed a week ago when I moved the TV unit out to access plugs... There is a large patch of brownish tide marks and white mould bits about 1.5ft x 1.5ft. It's not even discernable until you go up close...

I then realised that on the outside of the wall is the downpipe is overblocked (upstairs flat) and the external wall is soaked so it's obviously seeping through. I have arranged someone to come and unblock and clean the gutters. I've told the upstairs owner there may be further costs to repair the gutter.

What on earth do I do about the inside wall? I've cleaned with anti mould spray but should I put a dehumidifier running there. Should I further get a builder, damp specialist or someone else to take a look? Worried I'm exposing my DC to damp and mould...

If you cure the source of the damp (down pipe/gutters hopefully) then the wall should dry out. A dehumidifier can help to speed that along, as can heating and ventilation.

Then it's just damage repair, so cleaning down the wall with mould spray, checking any woodwork like skirting board for rot.

And don't let a damp "surveyor" convince you that your damp proof course has failed and the only way to save your soul house is to give them ££££££ to "fix it". Hopefully you've identified the source of the water ingress and once that's sorted, that will be the end of that.

We have a damp patch and what has helped was opening the windows (on a dry day) and putting a fan on it for a couple of hours a day. It's not completely dry yet but I think it's speeding it up ..

The wall will dry out by itself once you have sorted the guttering and stopped water coming in.

Please don't get any 'damp specialist' in! Unblock/repair the gutter, keep cleaning off mould with mould spray and let the wall dry out. Ventilator and heating on should speed it along, but it will dry on its own accord. You could spend an hour or two with a hairdryer once the gutter is repaired/cleaned if you are worried.

Thanks for the replies. I'm running the dehumidifier next to the wall and cleaned again with mould spray. There is no musty smell at least so I'm hoping it's just the water from the rain and will hopefully dry up after the gutter is cleared. Should I paint or coat the wall with something after it's dried out?

I did look into a damp specialist but after the comments here and reading some other threads sounds like I'm better off staying well clear.

Wait for it to get properly dry and then you'll probably need to paint it as there may be a water stain.

Don't worry at all - you know the cause so once that is fixed and the wall dries out, you just need to redecorate.

If the wall outside is brick just check the pointing has not been damaged once everything is dry.

If you fix the cause then dry the wall out and it should be fine on the inside.
we discovered a damp patch around DS’s window and tracked it down to some
perished seals. Replacement the seals, used a dehumidifier to dry the walls and then treated them with anti damp paint and re painted the area and it’s perfect now

@RM2013 did you get someone in to do the seals? How much did it cost if you don't mind me asking? I think ours need doing in our main bedroom

An ordinary domestic fan (not a fan heater) blowing on the damp will accelerate evaporation. Pull off wallpaper, if any.

@RewildingAmbridge I fortunately have a very handy Dad. He figured out that the constant wind and driving rain was coming up against the window as it’s at the back
of the house and a trio up the ladder showed that some of the external seals had perished. He just replaced the seals and it sorted the issue thankfully. We’ve had even more heavy rain and wind since but no further damp
issues