Will condensation harm my telescope?

[jefrs]

my 12" dob lives in my very drafty / slightly damp concrete slab garage.

its fine.

it gets dragged out and its already at ambient temp, it gets soaking with dew whilst observing and then gets dragged back in the garage once i;m done.

Next day it always seems to be dry (ish) and ready for action again.

Some of the exposed allen screw heads on the dob base have a spot of rust on them, but other than that it seems completely unharmed by living in there.

I cured the rust problem by putting an oil-filled electric radiator in my workshop (not the dilapidated shed). It doesn't do much heating but enough to keep dampness at bay and rust off my good tools.

If you're getting rust on the screws then your mirrors might be getting foxed.