Originally Posted by
3alarmer
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...if the lowest temps you get in there are 10*C, You might get a little condensation, but it will be minimal, even at those relative humidities.
Given your description, I think I'd be more inclined to regularly ventilate the garage, maybe even install a large fan blower in the wall or window, and regularly leave the door open about 6 inches at the bottom, unless you're in a place where you are worried about the people walking past trying to break in.
Those are about the winter weather conditions here where I live in California, and I have a garage full of bikes that do fine.
I do share your concerns about what is happening to that wall where the water is intruding.
The garage is ventilated by an unused chimney that was left open precisely for this reason. I have checked and so far I haven't seen any condensation on the bikes. However, I hanged them on the wall by the front wheel in summer using hooks, and when it started raining a few weeks ago, one of the humid spots appeared below the hooks. As I said it just feels humid to the touch. There's no water dripping or even reaching the floor, and nothing more than the back tire of one of the bikes is touching the humid part of the wall.
It seems that before I bought the house, the neighbour built a wall in his patio against my garage wall, but it doesn't reach the top of my wall and water filtrates between them. It doesn't help that the garage is not really well built and is totally uninsulated. Since the house was unhinhabited at that moment, nobody complained. It's not the friendliest of neighbours, so I don't have faith that it will be resolved quickly.