Hi, we have a two door garage, inside the garage it's very humid, looks like there is lot of moisture inside as there is no air circulating. And also it smells sometimes. what can I do to solve these problems. Thanks!!
You could paint the floor with a water proofing paint. Before doing that, Make sure you have roof vents or a ridge vent on the roof. If not, start there. The air must circulate. Otherwise just keep a window cracked. It's probably not a costly fix.
I didn't think about the slab. There are test kits that you can get that will tell you how much moisture is coming up from the floor. If there is too much you might want to consider putting a french drain around the perimiter.