How to Install Hardwood Flooring on a Radiant Heat Subfloor
by Myra Smith
A radiant-heated floor covered with a layer of hardwood brings to mind standing on a sun-warmed deck of a boat, enjoying the warmth under your feet. Laminated and engineered hardwoods and some species of American hardwoods, such as cherry and walnut, perform well when installed on radiant-heated subfloors. Strip hardwood flooring is a better choice than wide hardwood planks; the narrow strips adjust well to the expansion and contraction of the radiant-heated subfloor. Three types of installation of hardwood are gluing, nailing and floating floors.
Turn the radiant-heated floor on to the preferred operating setting at least 72 hours before beginning the flooring installation. Vacuum the subfloor and look for any lumps of leftover paint or drywall compound. Search for any raised or low areas on the subfloor, using a level. Sand raised areas level and fill low areas with leveling compound.
Place spacers around all walls to allow the correct amount of expansion gap; this gap is 3/8 inch to 1/2 inch.
Open several boxes of the hardwood flooring and check for color consistency. Using flooring from several boxes ensures that the flooring will be consistent in color across the entire area.
Install the hardwood flooring starting on an outside wall if possible; exterior walls are usually straighter than interior walls. Start at the farthest wall from the entry to avoid unnecessary traffic on the installed floor.
Spread mastic to the subfloor approximately 3 feet wide along the length of the beginning wall. Spread only as much mastic as you can comfortably cover with flooring in 20 minutes. Lay the first row of flooring, tongue side toward the center of the room. Tap the ends of the flooring with a tapping block and hammer to ensure a tight fit of the butt ends.
Cut the first board of the second row if necessary to stagger the butt ends of the flooring. Engage the groove side of the flooring onto the tongue side of the first row. Tap gently to close the seam between the boards. Continue spreading mastic and installing the flooring until reaching the opposite wall. The last row of the flooring may require trimming to fit into the remaining opening. Use a pull bar to nudge the boards into the previous row. Allow the floor to dry 24 hours before allowing light foot traffic.
Fasten hardwood flooring to the subfloor with nails or staples instead of mastic. Use the proper length of nails or staples to avoid penetrating the tubing or electrical coils of the radiant heating system beneath the subfloor. Rent a floor-nailing machine to progress faster. This machine drives the staples or nails at the proper angle into the tongue side of the flooring. Space the nails 6 to 8 inches apart. Hardwood floors installed with the nail method are ready for use immediately.
Lay out the first row of the floating floorboards, ensuring the butt ends firmly engaged. Cut the first board of the second row to stagger the butt end seams.
Raise the flooring boards at an angle to the subfloor, engage the tongue into the groove and push downward until it "clicks" into place. The finishing row of the flooring pulls into place with a pull bar.
Install baseboard by nailing to the walls, not the flooring. The floor is ready for immediate use.
Stapler/floor nailing machine
- Leveling compound
- Tapping block
- Pull bar
- Nails/ staples
- Stapler/floor nailing machine