How to Lay a Tongue and Groove Subfloor

Older houses have plank subfloors. If you are remodeling and find that some areas of the subfloor are damaged, you may choose to replace them with new tongue-and-groove boards that fit with the character of your house.

Laying Tongue-and-Groove Boards

Position the first board. Check that the board is the right way up. The tongue should be facing you. The following steps show you how to attach tongue-and-groove boards using blind nailing.

Nail Board Into Place

Place the nail where the board’s tongue meets the vertical edge. Position nail at 45-degree angle. Using a nail punch, tap it in place, until it sits below the surface.

Join Boards Together

Place the groove of the next board over the nailed tongue, covering the nails. Make sure that you join boards together over a joist.

Position Rows of Boards

Continue to position rows of boards across the floor. Use blind nailing, in the way shown, as you progress.

Position Final Board

On reaching the final board, scribe and cut to fit as required. A jigsaw is ideal for this. Fasten with finish nails.

Laying Tongue-and-Groove Chipboard (Particle Board)

Flooring-grade chipboard is usually made with tongue-and-groove edges, including the board’s shorter sides. Supporting blocking should be placed around the room’s perimeter. Position the first board across the joists. Insert wedges between the board and the wall, to create an expansion gap of 3/8 inch (10 mm).

Attach the Board

Screw the board in place, using chipboard screws. These should be inserted at 6-in (150-mm) intervals, positioned along a joist.

Place the Next Board

Apply wood glue along the tongue of the board. Then slot the next board in place.

Ensure a Tight Fit

To create a tight joint, tap the boards in place, using an offcut of chipboard as a knocking block.

Clean Excess Glue

As you tighten the boards, you will probably need to wipe away excess glue with a damp sponge.

Finishing and Fixing a Tongue-and-Groove Subfloor

Continue to lay the chipboard. At the edge of the room, mark and cut the boards to fit the remaining space and fix them with screws. Note: Gaining access underneath a tongue-and-groove floor is difficult, due to its interlocking structure. Note where access may be required. Remove the tongue from the board, and screw the board down. It can then be unscrewed and lifted easily. Fix extra blocking to support the edges of the access hatch.