Damp/Condensation

[Buchan]

The photos are where I store all my kit, guns to the right in a cupboard where have a small greenhouse heater and a little dehumidifier. We noticed some damp in there last year, and it's has seemed to be better this year with sealing up the door (hardly used).

What is this, I assume a fungus, but what? New dehumidifier going in the whole area and I'll be calling a builder to see if it is just condensation or damp seeping in round the front door - west facing so it gets the weather!

 

[finbar]

Could be salt coming through a think your problem is hot & cold spots !
Try & insulating the outside walls will help

 

[VSS]

Probably efflorescence, caused by salts in the render.

 

[muddy42]

Have you put a damp meter against the wall? What does the outside of the wall look like when its raining?

 

[TringSaint]

I would say that it’s either water ingress around the door frame or interstitial condensation that is pulling into the plaster layer.
Only way to fix that is to either raise the temp in the room or apply insulation with a vapour barrier in the room.
Chances are that there is no thermal break around the frame so if there is a gap then maybe some spray foam will help, but if it’s an old house with solid walls (I live in one of these!!) then it’s not easy to solve.

I just have the wood burner on in the old bit of our house all winter and it keeps the damp out nicely.

 

[Apthorpe]

As @VSS said, it looks very much like efflorescence. It looks as though the underlying render (grey) may be some what crumbly.
Is there a porch around the door, or a downpipe?
It looks like water has soaked into that wall, probably from above, and the interior wall is not breathable enough.

Is the plaster gypsum or lime, and the render cement or lime-based?

I would imagine that sealing up the door was possibly a mistake.

 

[Buchan]

Efflorescence, deliquescence and hygroscope - remember that from school! This looks like fungal sporing bodies though - about 2cm long, wispy, then again, also at school, I recall doing crystal gardens.
It's a 1920 rubble built house, no cavity, lime mortar in places I think.
I sealed the door gaps as rain was blowing in!

 

[Bo Diddley]

It just looks like damp, either coming from a poorly maintained exterior or possibly condensation from the inside, where warm air condenses on the coldest spot on the wall.

I've got an old bungalow with similar problems that I rent out. I've insulated some exterior walls, now doing a couple more.. It's like polishing a turd, I've decided I'm putting in planning for a new 3-bed house, and the old bungalow will get flattened. There is nothing nice about it to save.

 

[Norfolk Horn]

Move
Seriously if this problem has developed with time check gutters, downpipes, soakaway is functioning during storms and flashing is sound and that they aren't discharging on to the external wall.
Ground level hasn't been raised so making water penetrate the wall.
Internal water leaking from either fresh, heating or grey pipes under floor or from above.

 

[Will the chippy]

If it's a solid wall. Is it rendered on the outside? A good spray with Thompson's water seal will help the water penetration. Don't forget we've had a couple of months with a lot of rain.

 

[Martiniblack577]

Coming from above and working downwards - look externally for a failed low level roof join or grout line

Damp meters snake oi; l if it looks damp, it is damp.

 

[Buchan]

Thanks for replies so far

 

[Buchan]

Up date, I sprayed a mist of water at the growths and they disappeared. Looks like it was the salts!

 

[Goingback]

Wipe some bleach onto the damp surfaces...it never hurts and will quell any mould growth. Very valid points raised by previous posts. I have used Postive Input Ventilation is worth a look at and have significantly helped me in a few similar scenario's

 

[Ronin]

Had the same issue at our place

Cement render and the wrong paint by previous bodger owner

Cured with lime plaster an breathable paint

Both allow the moisture in the brick or stone to evaporate naturally and allow the house to breathe