Difference between rising damp and condensation

DIYidiot · 1 Jun 2009

Hi there,

My living room is full of black mouldy patches. It has three external walls and one internal wall. The patches are pretty much on all walls and in random places going up to the ceiling. Is there a way to tell if the damp patches are caused by condensation or rising damp. It's a very old end terrace victorian house by the way.

I have read many posts that the root cause of damp has to be identified correctly before treatment.

Many thanks
KJ

PS: If you know of a good company that can diagnoise and treat in Guildford that'd be much appreciated.

stuart45 · 1 Jun 2009

It sounds like condensation. Mould likes the purer water that it produces. The height also suggests it. You could also have rising and penetrating damp which are adding to the problem by making the walls colder.

AndrewSchofield · 2 Jun 2009

I've heard that if you stick a piece of kitchen foil to the wall and leave it - if the foil gets damp/wet on the room side then your problem is condensation, if the foil is damp/wet between the wall and the foil then the moisture is coming from the wall. Don't know if this works as i've never tried it myself but it seems to make sense logically?

Shytalkz · 2 Jun 2009

If it's more than 3' or so off the deck, then it's either penetrating damp or condensation at the upper levels, but you could also have rising damp low down too (qv many other threads for the existence or otherwise of RD...).

Are the windows always shut?Is it a room you use much? Have you got a gas or bottle heater that you use in there?

Could also be that previous occupier painted the exterior face of the external walls with silicone sealer, trapping moisture in the fabric - only way that can come out is inwards.

^woody^ · 2 Jun 2009

AndrewSchofield said:
I've heard that if you stick a piece of kitchen foil to the wall and leave it ...

The wall may be damp anyway, and the room may be humid anyway - and the wall may be damp because of the humidity or the humidity may be there because of a damp wall. So this is test unreliable in isolation.

The OP will have to decide if he is living in a cocoon with all the windows shut, washing on the rads, inadequate heating etc, or if there is visible problem outside which may be making the wall damp.

Black mould is condensation related. But what needs to be determined is if the condensation is being caused by the occupants, or the structure

DIYidiot · 2 Jun 2009

thanks! The radiator wasn't giving out full heat so I have had to get a portable oil heater into the room. Clothes are also dried on the radiator. So most likely condensation.

I will try the kitchen foil test. But then again as you say it could still be rising damp. Is there visible signs I can check on the structure for rising damp?

^woody^ · 2 Jun 2009

You are not going to get rising damp up to the ceiling

You will see evidence of rising dampness, just look around the bottoms of the walls and you will see it if it' there.

You have identified the most likely cause as soon as you said "oil heater", and then confirmed this by mentioning clothes on radiators. Look no further

diynot

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Difference between rising damp and condensation

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