Condensation in cold climate
 

ok, so i have a house rented out and have tenants living in there at the moment.

the tenants have complained that there is bad condensation in the house during winter, especially at night. and they use gas heating. winter nights get to about -10 degrees celcius, so its pretty damn cold. its an older house that is made of concrete blocks, with cement render on the outside, and plasterboard stuck directly on the inside of the concrete block. i dont think that water is pentrating from the outside, im pretty sure its from the inside.

anyone have any ideas on what causes and solutions there may be? especially those of you living in colder climates.

not sure if this belongs in this thread or in tilted knowledge, but i thought id post here for greater exposure.

I'm not a building expert, but I do know that when one side is warm and the other side is cold, and wherever between the two the temperature reaches the "dew point", the moisture in the air condenses out on the surface. I think you need a vapor barrier but it might not be so easy to retrofit into an already built structure. Sounds to me like you might have to remove the plasterboard, add a vapor barrier, put up new board. Another possibility is add a vapor barrier to the plasterboard and then cover it with another layer ...but I'm not sure that is good building practice.

Are they adding to natural humidity? Hang-drying clothes, real clothes dryer but isn't vented properly, using a hot tub, etc?

Cyrnel might be on to something. I think there would be other signs if the moisture was coming from the walls, such as stains, bubbly wallpapers and such. How is the house ventilated? We throw open the windows for a few minutes once or twice a day during winter to change the air, it's a bit nippy for a while afterwards but since everything else is still warm the air heats up pretty fast.
The bathrooms and kitchen needs to be aired out well, after a shower a window should be opened to let the steam out, same after cooking something or doing the dishes.
How well insulated are the windows by the way? We have modern triple-glass ones, and get very little condensation on them since they don't get as cold as double- or single-glass windows.
So my advice is to reduce the amount of moisture in the air by strategic ventilation and make the cold spots less cold.

This is the kind of problem report that motivates a walkthrough. You don't want to fix the plaster, mold, flooring, window issues resulting from too much moisture. If they don't say "ahhhh, didn'tthinkofthat", and take care of it themselves, give notice and visit on a cold morning or evening to see what's going on.

the house needs better ventilation. ask them to open a small window on either side of the house (or install proper venting on the roof).

it should be an easy fix.

Where is the condensation? on windows? door knobs? If windows you can probably better insulated windows if they're so anal about it (the kind with 2+ layers of glass with a vacuum between them). I'm not sure if it may work but maybe you can try to find some anti-fog spray or coating for the windows that way the condensation may be less prone to stick.. dunno if that would work but worth a shot.

If its on the doorknobs i dunno what you can really do except maybe get a plastic handle or maybe rubber coating or maybe have knit a little sock for the knob.

But yea there's gotta be a something going on.. maybe they take extra hot showers or something and the bathroom needs a fan/vent. Maybe the dishwasher (if there is one) is the culprit. Maybe the toilet is using hot water instead of cold. Could be anything, really.

Edit: I'm kinda tired and bored and just spewing that stuff out of my ass. But maybe some of it can be useful,.. I've been told on many occasions that i have a smart ass. :D