"blueman" wrote in message
...
We have an attached 1 car garage which sits on a concrete slab.

The concrete slab is visibly damp (but no puddles) and the air is
beginning to smell musty.

Is the concrete sealed? If not, this could be moisture wicking up through
the concrete.

What is the best way to fix this?
- Keep garage door and/or windows open for several hours a day?

This is the best way to make sure that it dries out, but won't solve the
problem.

- Buy another humidifier? (we already use one in our basement and
would rather not have to buy and operate another one in the garage?

A humidifier PUTS moisture into the air. What you'd want is a DEhumidifier.
This will dry the air and could help, but it doesn't solve the actual
problem.

- Do nothing and wait for cooler weather to come in the fall?

It might get worse with the cooler weather.

- Other suggestions?

I'd try and dry the garage as best as possible and seal the concrete. After
that I'd ensure that the drainage around the garage is good. You may need to
trench around it and install a "french drain".