# Basement Garage with Concrete Slab: To Vent or not to Vent



## Gary in WA (Mar 11, 2009)

I would put 1' of foam board on the below grade walls, then wallboard. Cut a high and a low vent in the walls, on opposite ends of the space. Similar to FHA's requirements in garages, 35 years ago. Try to get some air movement to reduce the moist, stagnant air. Leave it natural, unless you live in your vehicles. Seal the concrete slab with a quality sealer. Be safe, G


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## N-GA-Homeowner (May 27, 2009)

*Wallboard & Concrete Sealer*

Dear G:
Thanks for your posting. What type of Wallboard do you install if you were me? We assume the paperless type, or a PVC-type wallboard? 
And, what type of concrete sealer might you suggest? Thank you.
N-GA


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## Just Bill (Dec 21, 2008)

Cool masonary surfaces and high humidity equals condensation, which gives rise to mold/mildew. To test for hydrostatic water pressure under the floor, tape a 16" piece of aluminum foil or plastic to the floor, seal all sides. Check after 2-3 days, if dry, you cna do most anything you want with the floor; damp, you have a small problem and the floor will need special treatment for any type floor covering; wet, forget it, major work to instll floor coverings. Wall can be insulated with rigid foam, but it must be covered with drywal for fire code. Owens Corning, the pink stuff, has a 2" foam with slot in the panels for furring strip. Tapcons secure the foam/furring strips to the walls, and yiou can install drywall directly to the furring strips.

Ventilating a garage can be tricky, depending on fire codes. Wall openings between living space and garage are carefully regulated to prevent fire travel. I found nothing in IRC about openings to the outside, provided there are no combustible materials around the opening. So a vent fan to the outside might be OK, check local code.


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