How to Lay Hardwood Flooring on Heated Concrete

Install a layer of 8 mm polyethylene vapor barrier plastic over the entire heated concrete slab. Run the plastic up the walls 2 to 3 inches to provide additional protection. Overlap strips of plastic by 6 inches, sealing the gaps thoroughly with duct tape.

Cut panels of 3/4-inch plywood into planks measuring 2 feet by 8 feet. Turn the panels over and score 12-inch grids into the backside of the wood, to a depth of 3/8-inch, using a circular saw.

Spread a thin layer of asphalt mastic over the vapor barrier plastic using a 1/4-inch notched trowel to ensure the mastic is even. Lay the planks of plywood into place, leaving a 3/4-inch space between each panel and the wall and 1/4-inch gaps between adjacent panels. This is to allow for swelling and shrinkage that occurs with changes in temperature. Press firmly on each panel of plywood to embed it in the asphalt mastic.

Acclimate the hardwood flooring planks to the room for at least 72 hours before installing them. When installing hardwood floors over heated concrete floors, it is advisable to use planks that are 3 inches wide or less. The hardwood flooring should be installed perpendicularly to the plywood for maximum strength.

Leave a 3/4-inch gap between the hardwood flooring planks and the walls to allow for swelling and shrinkage. Spread flooring adhesive on the plywood using a notched trowel, covering a space that will accommodate two to three rows of hardwood flooring at one time.

Lay the first row of flooring against the wall, leaving the 3/4-inch gap, with the tongue side facing the interior of the room. Press firmly on the hardwood planks to ensure a good bond between the flooring and the plywood.

Position the second row of flooring against the first, staggering the wood approximately 6 inches, fitting the tongues of the first row into the grooves of the second row, and press the hardwood firmly into place. Holding a tapping block against the hardwood, tap it gently with a hammer to firmly secure the two rows of boards together.

Continue laying the hardwood planks in this manner, staggering each row and securing them with the tapping block, until the entire floor is covered. If you need to cut a hardwood plank, put it face down and cut it to the proper length with a circular saw.

Allow the hardwood flooring to cure in place for 24 hours before walking on it. Put the baseboards in place, securing them to the wall with finishing nails for a polished look.