How to Keep Dust From Coming Up into the House From the Basement Without Covering the Wood Beams

Look around the perimeter of the foundation around the floor joists to locate gaps where air might get through. Use all-purpose caulk to fill in any cracks that are 1/4-inch or smaller, using a caulk gun. Squeeze a thin bead of caulk over the cracks and then press the caulk into the cavities smoothly with a gloved finger.

Spray expanding foam into areas larger than 1/4-inch. Some of the typical areas where air passes are around gas or water pipes, along wiring entrances and around any vents. Spray only enough to fill in the bottom of the gap, and not up into the floor above. Follow the manufacturer’s instructions for drying. Use high temperature caulk for sealing the gaps around your furnace exhaust flue.

Insulate the areas between the floor joists with rigid foam board or spray foam. This will block the passage of air, keeping cold and dusty air from the basement from entering your living spaces. Cut foam sections to fit tightly between the joists. Spray a bead of expanding foam around the perimeter of the rigid foam to seal off the space.

Add insulation to the rim joists where the floor meets the concrete foundation. This will prevent any cold air leaks from outside. Use spray foam or rigid foam board and seal off the perimeters of the rigid foam with spray foam. Use a utility knife to cut the rigid foam board to size after measuring each opening.