How to Convert a Cellar Into a Basement

Have your home inspected for any water leaks. Leaks and drainage problems commonly occur near the bottom level of the house, and you need to ensure that the area will not allow water inside the structure or your walls can develop mold. Have a contractor add a cavity drain membrane to waterproof the cellar.

Hire professionals to add sewer or electrical lines. You might need to upgrade your septic tank or electric panel to operate a new floor of your house. Discuss necessary additions to the heating and cooling system with an HVAC specialist. A structural engineer can tell you if you have adequate head space or if you need to make any changes to the foundation.

Add insulation. Use foam adhesive to glue 3/4-inch extruded foam insulation to the foundation walls. This type of insulation does a good job of conforming around masonry walls and comes in yellow, blue or pink. Cut the insulation sheets as needed to work around obstructions. Caulk around any seams with a caulking gun.

Measure each wall in your cellar. Mark notations for any obstructions, pipes or electrical lines.

Use a table saw to cut 2-by-4s the same width as each wall. These will form the bottom and top plates for your framing. Make a mark on each plate every 16 inches for the studs.

Add constructive adhesive to one bottom plate. Butt the bottom plate against the insulation panel of the wall you measured this bottom plate for. Anchor the bottom plate into place with concrete screws.

Cut 2-by-4 blocking to add to the ceiling joists to help support your top plate. Nail them in place every three feet with 2 3/8-inch-long nails.

Add the top plate. Use 3-inch screws to screw the top plate into the blocking.

Measure the distance between the bottom and top plate. Cut studs to the same size. Toenail them into place with 2 3/8-inch-long nails hammered into the sides and center.

Measure two inches below the lowest piece of ductwork. Snap a chalk line at this measurement. Nail a 2-by-4 to the wall studs at this location.

Make soffits to cover ductwork. Measure 2 1/2 inches above the ductwork. Rip half-inch strips of plywood to the soffit's depth. Screw 2-by-2s to the edge of the plywood with 1 5/8-inch long screws. Nail the soffits to the ceiling joists with 3-inch-long screws.

Add drywall around the room, and secure it in place with 3-inch long drywall screws. Use drywall tape between seams.

Add ceiling hooks to your ceiling joists to support a suspended ceiling. Thread metal wire through the hooks, and hang metal beams from the support wire. Place a cross-t between each 2-foot section of the metal beams to form a grid. Add ceiling tiles to each 2-foot square.

Install flooring. Add a layer of concrete if your cellar has no existing flooring. Waterproofed flooring materials that protect your flooring from any future water damage are available in tile, engineered wood planks or carpet. Roll a polyethylene pad over the concrete flooring. Continue to roll out sections of the pad until your entire floor is covered. Install the floating, waterproofed material on top of the pad, according to the manufacturer's instructions. This project should not require the use of any type of adhesive, but you might need to hammer or lock pieces together.

Paint the room a light color. Cellars often lack adequate natural light, so a lighter color helps to avoid the feel of a dark cave.

Add lighting. Pocket lights can add lighting all over the space. Floor lamps and table lamps can also help illuminate the space.

Add furnishings and accessories of your choice.