ᐅ Closet Against an Insulated Exterior Wall – Risk of Mold?

Hello dear community,

Due to limited space, I want to place a large wardrobe against an exterior wall. It would have a gap of only 2-3 cm (1 inch), no more. Normally, as far as I know, this is not recommended because of the risk of mold, but I have read online that this can be done with very well-insulated walls.

The wall is made of concrete with added external thermal insulation. The building envelope has a U-value of 0.37 W/(m²K), and the windows have a U-value of 0.7 W/(m²K). Overall, the building achieves an energy rating of B on the energy certificate, with an energy demand of 59 kWh/(m²a).

Do you think this insulation level is sufficient to avoid any mold risk? How would you assess this situation?

Thank you very much and best regards!

New build? Well-ventilated room or rather seldom ventilated? For example, what is the current humidity level in the room?

Ötzi Ötztaler schrieb:

New build? Well-ventilated room or rather infrequently ventilated? For example, what is the current humidity level in the room?

Building from the late 1970s that has been energy retrofitted. Daily window ventilation is done. Unfortunately, I don’t know the humidity level because I haven’t moved in yet. However, I could measure it in the next few days when I visit again.

If it’s a reasonably well-heated and regularly ventilated room, it’s generally safe to take that risk.

However, if you enjoy the typical experience of a retrofitted and airtight renovated older building—where you feel like you’re running into a vapor barrier as soon as you enter in winter—ventilate only sporadically, and heat poorly, then there is still a small risk. So it’s entirely up to you!

P.S.: Ventilating once a day might just barely be enough to prevent mold with some luck, but the air is definitely healthier and more pleasant when ventilated several times.

Hmm, thank you very much for your contribution.

Would it perhaps make sense to also install ventilation grilles in the back panel of the cabinet or to place a toe-kick heater (also known as heating cable) behind the cabinet?

Phew, I'm not really familiar with that. The two measures certainly won't make things worse. However, the most important thing is that the base humidity level in the room is not close to critical. And to be honest, if the fear of mold behind the wardrobe means you always ventilate well and at least heat a little, then having the wardrobe against the wall is actually more of a gain than a risk. Look on the bright side.