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Condensation problems


heather

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We are having a problem with condensation in our house. it is a traditional village house in the Cevennes with an interesting layout. Imagine a  long rectangular house built of drystane with no internal staircase. this is the original house. like many houses here it backs on to a cliff-face with the land level with the second floor. On the ground floor a  cellar is built into the cliff and a stair runs up the rock to the door on the first floor. above this is a gap between the original house and the cliff. In more recent times ( somewhere in the 20th century! ) the stairwell has been extended upwards and narrow rooms added, a WC, kitchen, shower room and store. this has been done in concrete and glass bricks and most of it roofed over with fish-scale slate. Because the outside wall is natural bedrock there is always some moisture and in the summer this is not a problem as there is adequate drainage from the cellar. Now that the winter has arrived and the outside tempreture is below freezing, condensation from the kitchen and WC is running down the walls and dripping off the ceilings. The WC is the worse affected as it is at the top and is basically a concrete box with a flat roof. We are experimenting with different forms of heating; so far with little success.

Has anyone out there had similar problems to deal with? Any tips would be very welcome.

Heather

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Hi,   Condensation is normally a problem with the diferance of the inside and outside temperature being within the dew point of  water, the only way is to either reduce the room temperature by adding a vent or increasing the temperature outside of the dew point, this could be a problem with your setup as the rock could fluctuate in temperature often during the day making it hard to match a better answer maybe to install a false wall with insulation against the problem walls giving a thin void from the walls against the rock and vent the break if possible so youronly trying to heat the room and not the rock/wall

Dave

 

 

'Problems are always small, it's the remedys that take the time'[8-)]

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Hello Heather

Large wood burners remove a great deal of moisture from the air, plus create a constant airflow which tends to prevent mould. This is a simple solution which we have also used in a number of large workshops where metal tools were being coated with a rust film over night, a wood stove cured this problem. 

Jamie       

 

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Thank you all very much for your ideas about this. I now have plenty to think about.

We have had the house for nine months now, so are getting a good idea of how it behaves in different weather conditions. Part of the problem in the last month has been the natural reaction to keep all the windows and doors shut and hold in the heat, so of course no ventilation. with the new year we are making plans to get all the necessary jobs done in the house and sorting out this heating/ventilation balance will be a priority.

Thanks again for your advice

Heather

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Something else that is very common in here France is parafin!!! I if you are using that to heat your house then it will contribute a great deal to your condensation because it is very hydroscopic, collects and holds loads of water, and when burnt it gives it back to the atmosphere. I am fully convinced that it is the reason that dehumidifiers are so widespread here. Both the active, electric, and pasive, pads in boxes, are on sale everywhere through the winter. I am also told that LPG is not too good either, when it's used in the small portable heaters?

But as has been said ventilation is one of the most importaint things. If you have an extractor fan in the loo/bathroom and the kitchen then leave it on. The type that I mean is the type that seems to be the normal fit in French houses and can only normally be switched of by flicking the circuit breaker at the mains. The switch normally only has 2 positions, normal and rapid. An open chimney is also an asset...

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We had a major condensation problem a while back, until it was explained to us about the shutters (if you have them) and the way most French windows shut. Apparently, it is normal at night to close the shutters, but you close the window with the locking (turning) handle, and hold the other side of the window fast in the knob, not actually closing the window. We thought we would freeze, but having just come back from France when it was minus 9 some nights, it does work and we had no condensation. The woodburner kept us warm. Even when we are away, this is now what we do. Lock the shutters tight but bot lock the windows, leave them open, but held fast in the handle of the locking side - sounds strange, but if you have this type of window it certainly works on the condensation. Bonne Chance.

Keni

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We had the same problem. We have no central heating only a large woodburner. If you have shutters, close them at night as this seems to solve the problem. I have no idea why but it works! (Now you know why many french houses are shuttered up all day and night)

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it's difficult to eliminate penetrating damp if the ground level outside is higher than the floor level indoors.

condensation is a different type of damp altogether.  it tends to be found on the inside of an external corner furthest from a bathroom or kitchen. as someone has already said, ventilation is key.  you'd be surprised how much water vapour is generated by boiling the kettle, showering and even  breathing.  the point that someone else has made about paraffin heaters is also relevant.  these heaters do generation a lot of water vapour.  condensation is one type of damp problem that is easily resolved. 

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