How problematic are the exterior walls in an aerated concrete house? Is it worth worrying about dampness?
There is a house made of aerated concrete (375mm), soon I will start exterior decoration. Outside will be insulated with mineral wool (EIFS facade). The heating system – gas. Who knows if there is a problem:
1. In the rooms of the outer walls can not lean against the furniture
2. In one of the rooms I want to finish all the walls with wood. Won't it get moldy near the exterior walls?
Answer
This is more of a problem of "lack of" insulation and lack of (poor) ventilation. But, more precisely, not poor ventilation, but increased humidity in the room (which does not necessarily only happen with poor ventilation).
The mechanism is approximately this – the furniture (or wooden cladding), when installed tightly against the wall, impairs the heating of the wall by room air and radiation, but allows air moisture (moisture in the air can "move" and when the air is stationary). That is, the wall behind the furniture is definitely colder than the open walls, and the air is just as humid as the room as a whole. There will be a combination of moisture temperature of wall material corresponding to dew point – there will be humidification of the wall and conditions for mold growth.
The better insulated the wall, the lower the temperature difference in the room and behind the wall cladding/furniture. The less chance of mold growing there.
Ventilation, of course, also reduces the chances of mold growing, but if the climate is humid or a humidifier achieves "normal" humidity in the room, even with "normal" ventilation can be enough to grow mold, if the "closed" part of the wall is cold enough.
The wall is already insulated. You can still ventilate the space behind the wood paneling by making ventilation "slots" at the bottom and top, and the paneling is done on vertical rails. Furniture is usually just recommended to put not close to the wall (especially in the corners), and with a small gap.
It also depends on the ability of the wall to output moisture to the street – you have a suitable option for this too, but in order not to worsen, it is better to leave the bare aerated concrete behind the cladding.
