We have a 9m long large steel garage from Siebau.
We ordered the anti-condensate for the ceiling at the same time to prevent dripping and after just over 1 year we have not noticed a single drop so far. Friends of ours also have a Siebau garage without the anti-condensate and they seem to have dripping on the car 3-4 times a year in unfavorable weather conditions. So I wouldn’t exactly call it a dripstone cave.
However, there is a certain level of humidity in the garage. Last autumn I left my bit suitcase in the garage for a few days. It quickly started to rust, so it was quickly stored again in the utility room. But I don’t believe it would have been different in concrete garages in autumn, since in a concrete garage the water from the car cannot drain away at all. In terms of air circulation and water drainage, in my opinion the steel garage is even superior to the precast concrete garage.
Inside the garage and over the foundation we had normal paving stones laid. At the edge stones, which are visible both outside and inside, moisture seeps inward a bit when it rains, so you have to be careful that nothing moisture-sensitive is standing or lying there. In general, moisture-sensitive items should not stand on the floor.
Another somewhat negative point is the mounting options for garden tools, light switches, bike racks, etc. If you don’t want to buy the, in my opinion, overpriced accessory products from the garage manufacturers, you have to come up with something without having to drill through the outer shell. On one side I built a substructure using OSB boards so that I could use the more affordable standard products for hangings.
Overall, we are actually satisfied. Let’s see how it looks in 20 years.