DIY Doctor UK DIY Forums

Hi, can anyone help us with our damp problem???

We moved into our 1950's bungalow about eight months ago. The full structural survey showed no significant damp problems. It just flagged up a corner of our bedroom which the surveyor put down to a external step being too high relative to the damp proof course.

Two months ago I noticed small black spots of mould growing in the lower parts of the two external walls of our bedroom (north and east facing). The problem is particularly bad in the bay window. The same problem, although to a lesser extent is present in the bay window of the living room (east facing).

The childrens' bedrooms are located in the extension which was built in the 1980's. The condensation in these rooms is confined to the lower part of the window. The walls are completely dry.

The extension has a concrete floor, whilst the original part of the building has a wooden floor. I have checked the external walls and can see no obvious cracks or problems.

I am assuming it is likely to be condensation due to the locations of the problems. Now the weather is cold, the skirting boards are literally running with water. The mould is also quick to reappear (we periodically remove it with a mildew remover).

We have tried to limit the moisture in the air - washing dried outside where possible, extractor fans in bathroom and kitchen, window left open for an hour or two during the day. The furniture has been moved away from the affected walls. Is spite of all these the walls and skirting still run with water.

What can we try next? Any suggestions will be gratefully received.

Happy New Year.

It was only after the first oil scare that people started to think about heating and insulation.
Prior to that designers and builders gave little or no thought to the cost of heating a home.
Now people are encouraged to insulate, close off the natural ventilation and even turn their heating off when they go to work, or go to bed.
All these things conspire to make a damp cold home.
It is estimated that each person puts about 2.5 litres of water vapour into a home in the course of 24 hours. When you are all at home during the evening and night this is a lot of water vapour. If the ventilation cannot cope the result is cold damp walls and streaming windows.
The habit of turning off the bathroom and kitchen extractor fans because they cause a unwelcome draft and putting things on radiators to dry does not help.
Running the kitchen extractor fan without opening a window doesn't help,it pushes air that you have paid to heat outside and drags in more cold air though walls, floors etc in other rooms.
Add these bad habits to bad building where walls are often cold, damp, full of small holes and you have an ideal location for mould growth.
Our homes are full of spores that are looking for damp walls, curtains, bedding etc to grow.
The solution, keep the temperatures of rooms steady, a drop in temperature of more than 2 degrees C will result in condensation.
Carry on as you are, keep everything away from the walls to promote warm air circulation. (Except don't open the windows so much, humidity can come in on days of high external humidity - we've had nine days of 24 hour total humidity so far this year.) And 52 days since the beginning of October where the humidity has reached saturation at some point during the day.
Buy a de-humidifier and use it initially 24/7 for a couple of weeks until the home dries out.
Buy a humidistat to see whats happening in your home and outside.