Dampness

[Gibbon]

Sounds like condensation to me. Simple test. Sellotape a piece of palstic to the wall make sure there is no air between it and the wall and see if the plastic becomes damp. If it does then condensation. If not sell the house.

To alleviate condensation dry line the wall or buy a dehumidifier for the room.

HTH

[FiveTimes]

Neither of the affected rooms is heated & there's a lot of black mould appearing on the surface of the plaster.

condensation - improve the air flow,

[wurzel]

I'm in the process in solving a damp problem in a house I let, it's an old victorian house.

I've been using a company called Peter Cox, who seem to know their stuff.

Will check them out

Sounds like condensation to me. Simple test. Sellotape a piece of palstic to the wall make sure there is no air between it and the wall and see if the plastic becomes damp. If it does then condensation. If not sell the house.

To alleviate condensation dry line the wall or buy a dehumidifier for the room.

HTH

Will try that out.

Cheers.

[DaveB]

Neither of the affected rooms is heated & there's a lot of black mould appearing on the surface of the plaster.

Condensation.

Check the plaster, most of it will probably have to come off if it's that bad. If so strip it off and get a de-humidifier in the affected rooms and run it for a couple of weeks to dry out the walls before you replaster. If you do the job yourself make sure you wear a respirator or at least a face mask, that mold can be nasty if you breath it in. Make sure the rooms are well ventilated and get some heating in there if you can or a permanant dehumidifier.

There is not a lot else you can do about it as the source of the damp is the air in the room itself.

[conned tractor]

Sounds like condensation to me. Simple test. Sellotape a piece of palstic to the wall make sure there is no air between it and the wall and see if the plastic becomes damp. If it does then condensation. If not sell the house.

HTH

Top tip! I like that one.

[Paddy]

Just wondering if any of you DIY nuts might be able to give me some advice on what could be causing dampness in my house.
I get it on the on the north-west facing wall of the house (i.e. the one that gets all the rain but hardly any sunshine). It's so bad that it causes the plaster on the inside walls to blister and crumble away.

I don't think this is caused by rising damp as the problem is the same both upstairs and downstairs. The roof is sound and so is the pointing. I'm at a complete loss as to what to do with it but I don't want to hire a bunch of flakes to fleece me just yet so any ideas would be most welcome.

Presuming the gutters and roof are in good condition; the most obvious problem in an old house will be a bridged cavity.

Many old house have hand-made bricks that are porous and the cement is usually a weak lime mortar mix. Over the years it goes to powder and fills up the cavity or at least bridges it. The water will then penetrate to the inside wall.

To rectify you will need to take a few bricks out either internal or external and clear out the cavity stage by stage. Usually at the lower end.

You will need to open up one part, clear out and re-brick the opening. While doing this you can take the opportunity to fit a new DPC (Plastic). I have cut out bricks in one complete property half a meter at a time with no problems of sinking. This method is the correct way, costs the least in materials but does take time however, you can do it stage by stage over the summer without problems. If you do it yourself, you know it will be a good job.

Some builders will try and fob you off with chemical DPCs or a coating for the bricks. This method merely a quick and dirty fix and will not last.

[wurzel]

Presuming the gutters and roof are in good condition; the most obvious problem in an old house will be a bridged cavity.

Many old house have hand-made bricks that are porous and the cement is usually a weak lime mortar mix. Over the years it goes to powder and fills up the cavity or at least bridges it. The water will then penetrate to the inside wall.

To rectify you will need to take a few bricks out either internal or external and clear out the cavity stage by stage. Usually at the lower end.

You will need to open up one part, clear out and re-brick the opening. While doing this you can take the opportunity to fit a new DPC (Plastic). I have cut out bricks in one complete property half a meter at a time with no problems of sinking. This method is the correct way, costs the least in materials but does take time however, you can do it stage by stage over the summer without problems. If you do it yourself, you know it will be a good job.

Some builders will try and fob you off with chemical DPCs or a coating for the bricks. This method merely a quick and dirty fix and will not last.

Walls are made of stone. As far as cavities are concerned, there aren't any; just rubble infill.

[Paddy]

Walls are made of stone. As far as cavities are concerned, there aren't any; just rubble infill.

Flint or chalk?

[al_cam]

For it to be condensation, there has to be a significant source of water - drying clothes either with or without tumble drier is a common cause showers/baths/washing up less so as the water is drained away after use.

Obvious question, but is it always damp or weather dependent?

My money goes on the roof - regardless of whether you had it done in recent years or not, flat roofs will always leak eventually so my advice would be to put a pitched roof on it. If it is a big roof area then definitely get guttering - these guys that do the zinc stuff from sheet can do some amazing shapes and can probably do curves.
Other possibilities are a downpipe from the main part of the house being blocked or maybe a disused chimney?.

I have a 250 year old house with no damp problems - all pitched roof.

Al.

[wurzel]

Flint or chalk?

Limestone