Damp/ water problem on stone wall

ColoFio

Hi all

Looking for some advise please. We bought a converted 19th century farmhouse last year. Moved in just before last xmas. Had no problems until the summer. The gable wall of the house, stone very thick, has damp/wet patches and is leading to mildew on the walls.

Background info - the internal and external walls are plastered. The bedroom above this room (sitting room) seems to have previously had damp problems on the same wall but now has none. The external plaster has been redone from the chimney to ground floor ceiling level so this must have solved that problem. There is a patch of wooden floor in the sitting room which seems to have been replaced at the damp area. The affected wall has a large old fashioned open fireplace where we have installed a new stove and new pipes and sealed the large opening. There is a second chimney at the other end of this room and we have blocked at top and bottom to prevent draughts. This room is extremely large and the windows have no vents. Both sides of the stove are affected. Sometimes the walls are weeping, sometimes they are bone dry for weeks.

On one side there was a downpipe puring into the ground. We replaced this and dug out around this wall and put down new drainage. This did nothing to alleviate the problem inside. The water marks are coming from ground up but are spreading horizontally at particularly bad times to the adjoinging walls and its these walls that develop mildew.

Two lots of builders have advised us that its not rising dampo. One says it is solely a ventilation problem. This doesnt seem to marry with the fact it started at summer when all windows and doors were open. The other first though maybe it was a leaking pipe from well but no pipes were found when we dug out.

Sorry for long post but fed up of trying to solve and have very small baby in house

Bateman

I lived in a decent-sized but poorly-ventilated apartment, and had mould on the walls. We now live in a house and have had to have significant professional damp-treatment done.

From the details above, I'd tend to agree with whoever is telling you it's ventilation-related rather than an actual physical source of damp.

Bateman

http://www.thepropertypin.com/viewtopic.php?f=10&t=61407&start=30

Bit more info, insulation thread that turned into discussion re: ventilation

oppenheimer1

ColoFio wrote: »

Hi all

Looking for some advise please. We bought a converted 19th century farmhouse last year. Moved in just before last xmas. Had no problems until the summer. The gable wall of the house, stone very thick, has damp/wet patches and is leading to mildew on the walls.

Background info - the internal and external walls are plastered. The bedroom above this room (sitting room) seems to have previously had damp problems on the same wall but now has none. The external plaster has been redone from the chimney to ground floor ceiling level so this must have solved that problem. There is a patch of wooden floor in the sitting room which seems to have been replaced at the damp area. The affected wall has a large old fashioned open fireplace where we have installed a new stove and new pipes and sealed the large opening. There is a second chimney at the other end of this room and we have blocked at top and bottom to prevent draughts. This room is extremely large and the windows have no vents. Both sides of the stove are affected. Sometimes the walls are weeping, sometimes they are bone dry for weeks.

On one side there was a downpipe puring into the ground. We replaced this and dug out around this wall and put down new drainage. This did nothing to alleviate the problem inside. The water marks are coming from ground up but are spreading horizontally at particularly bad times to the adjoinging walls and its these walls that develop mildew.

Two lots of builders have advised us that its not rising dampo. One says it is solely a ventilation problem. This doesnt seem to marry with the fact it started at summer when all windows and doors were open. The other first though maybe it was a leaking pipe from well but no pipes were found when we dug out.

Sorry for long post but fed up of trying to solve and have very small baby in house

To be honest with you, without seeing it, it could be any number of issues. Firstly, is the house generally damp and do the windows fog up? If you find that this is the case, then it might be a ventilation problem. If the indoor relative humidity rises above 60% and the air temp is 20C and the external walls stay cool at a 14C or less, then the walls will sweat. The only way around this is to either reduce the humidity indoors or insulate the walls (insulating can bring other issues however). A stopgap measure is to install a dehumidifier but these have an expensive long term cost associated with them.

You also say that the wall has just been plastered. Can you tell us what kind of plaster was used? Modern sand and cement renders are incompatible with stone walls built with lime mortars and only lime renders should be used. The link below explains the phenomenon far better than I ever could:

http://www.heritage-house.org/damp-problems-caused-by-cement-render.html

Finally, are there any other faulty rainwater goods around the house?

GuitarMusic

A stopgap measure is to install a dehumidifier but these have an expensive long term cost associated with them.

As with most items the more you pay the better the quality.

Dehumidifiers such as the EcoAir DD122MK5 or Meaco DD8L contain energy-saving features with which the dehumidifier senses the RH in the air and automatically switches to the best setting for that humidiity level.

The catch 22 is that they save you energy consumption over the long term but are also more expensive to buy.

If you are using, or want to use, the dehumidifier frequently then they are worth buying.