We’ve a regular Victorian terrace, 2 up and 2 down with galley kitchen and toilet on the end of the kitchen.

The upstairs front bedroom has two windows and approximately midway between them and about a foot above the skiting board is a patch (about
30cm x 30cm) of damp/mould on the wall. We’ve had two people look at it and they’ve determined its due to a dead air spot and poor ventilation in the room. One quoted £700+ for a roof/loft mounted electrical heater vent system the other said wash the wall down in diluted bleach to kill the mould and to keep the windows open…even in winter.

Any other ideas/tips from the STW hive?

its a cold spot [ where water condenses] so deal with it by either
1. Make it warm so it wont
2. Ventilate it so it wont – makes it colder

which is basically what they said

I live in a similar property. Read this.

https://www.heritage-house.org/damp-and-condensation/managing-damp-in-old-buildings.html

Its come up on a couple of threads, but it seems damp is usually caused by people in the houses rather than something to do with the houses themselves.
You can do simple things to help.

Close bathroom door and open window after showers/baths
Close kitchen door (and open window if necessary) whilst cooking
If you dry laundry indoors, dehumidifier in that room.
Dehumidifier in room with damp spot

it likely is condesnation on a cold spot but just check the brickwork on the outside at the location, repair any cracked render or repoint any brickwork with dodgy pointing. A coat of something like Thompsons water shield to help the rain water run off may also help.

Then as above, control the damp produced inside, good extractor fans in kitchen and bathroom or using windows, don’t dry clothes inside if possible, and move air about the house by opening windows, make sure any airbricks are not blocked, even install one in this spot/close to it.

If you want to see the effect of any of changes or actions without waiting to see if mold will reappear after cleaning, get a cheap clock and weather station with humidity, they are only about a fiver. They will show how the humidity goes up if you shower with the window shut etc, and help you identify what to change.

Worth checking the guttering / roof / seals round windows to make sure there’s nothing getting in when it rains. We replaced our guttering, had some pointing done and filled in some gaps round our windows (amongst other things) and our damp vanished (100 year old terraced house).

You might want to check out these previous threads for a less than £700 option;
http://singletrackworld.com/forum/topic/positive-pressure-ventilation-loft-units-which
http://singletrackworld.com/forum/topic/nuaire-drimaster-heat-experiences

Having read lots on here about it, I bought a Nuair positive air pump. It sorted the problems of damp (and mold) but in the process discovered my neighbour had a rodent problem (more threads to read). All done and dusted now and with a small cottage I just keep two windows locked marginally ajar and that allows for the throughput of air (and condensation).
Couldn’t recommend these things highly enough and I would never have heard about them apart from on here.

If you do seal the outside use one of the sealants that still allow the substrate to breathe. They penetrate further into the brick/mortar, Thompson’s is only a surface treatment.

Read and understand the site that Cougar has linked before you spend any money.

I also live in a solid-wall house and fixed a couple of small damp patches with some water seal on the brickwork. I’ve also used the diluted bleach spray trick on mould – it does work.

Insulate the walls on the inside and fit triple glazing with a trickle vent.

I would echo the sentiment to read Cougars link.
I am by no means an expert, but I have solved 2 “damp” problems now by just replastering the damp patch.
Both issues were caused by previous leaks leaving salts in the plaster that leach out and attract mositure when you breathe out.
The first cost me a fortune as I had lots of other repairs done, after an RICS survey identified roof and pointing and other issues, the damp patch came back after this work was done, and it had been cleaned and repainted.
Then I got an independent damp specialist who showed it was salts by taking samples and measuring the salt content and a few other things.
He said the old plaster was full of salt and just to knock off and replaster the patch. I did, damp did not come back.
So only 3 months ago and another recurrent damp patch on a chimney breast. The previous owner roof repairs, chimney capped and vented, then repainted using stain block umpteen times. It always came back and no damp measurements using a meter.
So from my previous experience I paid the plaster 240 to strip damp patch, render and replaster. I painted 2 weeks later and it has been fine ever since. Time will tell I guess.
Google efflorescence.

As above. If it’s not a blocked off chimney breast. Plaster tends to go hygroscopic when it gets soaked (attracts moisture). Hack the soggy bits off and re-do it.

Similar issue for us in our bedroom. Very thin poorly, insulated wall as the bedroom is in the roof (chalet style) meant the wall was the coldest place in the house that water would condense. Wet and then would go mouldy. We fitted the positive pressure vent ourselves rather than pay £700 for the company to do it so it was around £250. Totally solved the problem.

When these houses were built they had airbricks and coal/open fires therefore the house breathed (oh, and no double glazing)……….just try putting an airbrick in the room (or even just drill a short line of holes for starters)……..bet the problem is no longer

pipiom nails it. the open fires. consider them a heat powered extractor, they shifted a LOT of air through the house. If I run one wood burner for a few hours (which will shift about half the air of an open fire) it pulls the humidity downstairs down by 5% or more. These houses were not designed to be air tight and CH’d

Have you got cavity wall insulation (assuming you have cavities)? Consider removing it if you do, it’s not suitable for your age of house. Two of our neighbors have damp issues since installation, one had it removed which fixed the issue.

I can only speak from personal experience: we have a victorian solid walled house. The best money we spent was for a positive input ventilation system, it did cost £700 for buy and install but removed condensation issues in 24hrs.

Thanks for all the coments and I’ve read Cougar’s link, it was really useful.

So, it doesn’t have cavity walls, the upstairs fireplaces were removed and sealed/blocked before we bought the house, it has 10yr old UPVC double glazed windows (without vents) and 300mm of loft insulation.

Another pecularity….. the dining room has a fireplace into which was an old gas boiler. We removed it and installed a Combi boiler in the kitchen about 12 years ago. We didn’t pull through/remove the flue though so there’s about 20cm of pipe jutting down the chimney. No biggie on looks, but recently a bit of water has started to come down the inside of the flue pipe. It’s not rain as it has only just started to happen in the last few months and happens regardless of rain or not. Condensation in the cold pipe?

Another +1 for the link posted by cougar.

It’s also worth noting for chimney breast staining, that to truly prevent hygroscopic salts reappearing, replaster with lime, nhl 3.5 and sand, obvs.

As for water from your unused flue, damp and condensation is predominantly due to lack of ventilation, therefore I’d look to see if it’s been recently blocked, dead bird, or nest.

Start with Retro fit trickle vents to the glazing as a low cost intervention + as above investigate what’s going on with the flue + look at the rest of the roof & elevations before going down the route of adding ventilation or insulation

Awesome, thanks all.