It's wet in here!

Q. I have a second home upstate, and the garage was converted to livable space. The dampness is really bad. The sheetrock walls are getting mildewed. They must not have put a vapor barrier in when pouring the concrete floor. Is there anything I can do to the floor to stop the moisture from coming through? Also, I need a leveling agent to level the floor.

A. You can solve the mildew problem, but you need to look at the whole condition, not just the floor. Examine the location, from roof to foundation, and try to determine the flow of rainwater and where it goes. Check to see how close to the ground the exterior wall materials end. A slab on the ground can mean that the exterior wall is so close that water can intrude at the edges. Basically you’re looking for the moisture source, how to prevent it, how to vent it and how to avoid contact with moisture.

After making sure there are no other places above ground level where water can sit or soak the walls, including any penetration such as windows, wires, conduit, sweating plumbing pipes or chimneys, check the heating and cooling of the room. You may have a humidity problem if you keep the temperature too low in winter or too high in the summer. Use a dehumidifier to see how much moisture you’re pulling out of the air. If you find you’re dumping the reservoir frequently, then humidity is a big concern. The walls and ceiling may not be insulated enough to prevent the temperature/humidity ratio from being too moist. Also, the slab needs rigid foam boards installed around the perimeter to at least 36 inches deep into the ground. This keeps the slab perimeter insulated from heat loss/cool gain, which also leads to moisture problems in the floor and wall base.