Advice on damp flaking wall.

urbanachiever1

Could anyone suggest what may be causing this damp fungal like growth on the wall of my bedroom? It is an exterior wall that is plastered but not painted on the outside. It is an upstairs room. Also any suggestions on how to treat it? many thanks in advance.




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BryanF

lets start with, what is

1. on the other side of this wall?
2. is it facing prevailing wind/rain?
3. is the external ground level lower than internal floor level?
4. is there adequate ventilation in the room ie a wall vent
5. is the wall vent blocked?
6. is there adequate heating in the room
7. is there any possible leaks from rooms above or gutters
8. do you own this or are you renting?

urbanachiever1

Thanks for your reply.
The worst of the dampness is where I have marked with an x on the picture below. Yes the wall is south west facing and so gets the prevailing wind and rain. i have watched the area in heavy rain and there does not appear to be too much water running down the wall. i wonder would a coat of paint or some sort of cladding on the outside wall help? The house does have an unused basement which is quite damp as the house is built on a hill and water gathers on the street in the front of the house after rain. There is no drain and appeals to the council for one have been in vain. Is it possible that dampness could rise from the basement and manifest itself like this on an upstairs wall? The room below (the hallway) while having a few mildew spots is not nearly as bad as the bedroom above. And the wall in the attic above the bedroom is relatively dry and clean. No, there is no wall vent in the room but there is adequate heating (gas fired central heating). I rent the house from a friend so we are working together on this. We will probably scrape the wall and repaint with some kind of sealing paint. I know this is only masking the problem.





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BryanF

so here's a couple of the main things i can see without an inspection

there is rising damp, which could be reduced at source through a variety of methods, including external drain,damp proofing and maybe painting etc.. but the fact that its a lesser problem on the lower and upper floors +you discounting the drying rain, suggests its either a leak or an internal surface condensation problem (you have not said if there is dry lining/painting/tanking or maybe a more breathable lime plaster on the floors below which could be masking the problem)


the one thing you sweep over here, is that there is no vent in the room.

over the last few decades when we all changed to PVC windows, sealed up the drafts, plastered with cement and blasted up the heat, we neglected to include ventilation in the mix - air movement and the removal of stale moisture laden air is essential

there is no insulation outside these walls and therefore there cold surface allows condensing of the internal moist air

so start with

• clean mould, opening the window permanently - check if things start to dry out (you can buy a damp meter on Amazon for about 50quid but your hand and visible inspection is often as good)
• externally check gutters, barge detail/ roof slates, (chat with neighbouring property as their wall looks a little discoloured too) from this angle your slates look a bit tired, have you been in the attic in this area lately?
• it maybe worth painting externally, but it would be best to assess and deal with rising damp as best you can first as the old plaster may actually be helping the wall to dry-out/expel moisture in sunny weather.
• get on to your council in writing explain/lie(i mean exaggerate) that your house is falling down from the water ponding outside, although the way the picture is taken I'm not sure if this is the issue, and i presume the basement is private property, so its up to you and your neighbour to deal with.. this might take the form of drains or tanking among other options
• now buy the time you considered the above you'll have a better idea if leaving the window open has helped the issue, which i suspect it will have, then it may be worth considering a mechanical ventilation system as-well as some appropriate insulation (by appropriate i mean nothing that will trap any dampness on the existing wall)

slowburner

My guess is that your problem is the result of water coming from above. Rising damp cannot go above approx 4'.

You'll need to investigate.

Looks to me as if there could be a drip or overspill from your neighbour's gutter (1)

Water at the junction of your neighbour's gable and your roof (2)- where's that going? Is there any flashing there and if there is, is it sound?
I suspect that this area could be the root of the problem

The area below 2 and 3 looks as if it could be damp

Looks like there's evidence of some water coming down the exterior of your gable (3) Is there a crack in the render just below the X?

Spread

The points made by BrianF and slowburner are valid. Perhaps I can add some others.
If the gable end was replastered sometime, then the joint between the blue wall and the grey wall may have opened a little - thereby allowing moisture ingress. Perhaps there was no water-proofer added to one of the coats.
You could dispell the lateral penetration theory by flicking water on the wall when it is dry and observing the suction. If it soaks in straight away, it could mean that in areas where the plaster thickness is less than others places that this could be the problem.
And lastly, if it is a sone house you may have a large flat imporous stone touching the outside render and the inside plaster. This would cause cold bridging which would cause condensation inside if the room temp was kept high. In the old days, these stones were called weeping stones.
Best of luck anyway.

Carlow52

OP: SB on the money here, this a leak combined with possibly a vertical and horz crack in the wall hence the L shape.