Big problem with damp in underbuild...help please

One of the bedroom walls has a damp area, we have bought an electric dehumidifier and it is collecting about a pint of water every two weeks, but we have no idea where its coming from, is this a normal amount? Any suggestions appreciated thanks.

Have you got good ventilation if any?

yes we leave the windows open slightly, the other bedroom and the lounge have no damp at all, its on the outside wall as there are damp patches there, but had no rain for two months so its definately an internal problem.

Hi you would probably be better getting a good recommend builder to take a look

Ask yourself some questions..
Is this bedroom in the underbuil?
Are there any pipes.drains,sewers near the wall?
Is there a kitchen or bathroom above?
Do you have a neighbouring wall near the damp area?
Is this a recent problem?
What is next to this room?
Try to find a reason, there must be a cause.
Is the paint / plaster flaking?
Damp is caused by moisture and to collect a pint of water from the air is massive....
Look for a leak
Check your water bill, have you used a similar amount as this time last year?

Whatever you do, get this sorted quickly.

Please update and let us know what the problem is.
Good luck.

If the damp penetration is below ground level then it is possibly ground water due to inadequate external waterproofing. There is a natural level of ground water (the "water table") which varies according to area. If the underbuild was built below the water table then waterproofing or de-watering is crucial. I stress this is only a possibility and you should consult an expert.

Ask a professional person who can inspect the site. No-one can answer this question without looking at it .

I notice the spanish stil have a habit of embedding copper pipes in the building fabric, a practice that was abandoned 30 years ago in the UK, because if you get a leak its virtually impossible to detect quickly. Are you sure there isnt a water pipe buried in or under the wall? Burying copper pipes in lime based mortar or concrete is fatal, over the years the lime in the cement corrodes the copper pipe until it develops pinhole leaks.

Most underbuilds suffer from damp as the damp course is above the building level. So it will always will be a problem unless you get a builder in to retrofit a damp course. Unfortunately not an easy task but well worth doing.