- 1). Set a piece of plywood in one corner of the floor, bordered by two walls. Leave a 1/2-inch space between the board and both walls.
- 2). Drive wood screws into the face of the board every 6 inches around the edges and across the whole surface.
- 3). Lay the second sheet off the end of the first piece, butting the ends tightly together. Screw it down in the same manner as the first piece. Continue setting the sheets end to end along the edge of the floor.
- 4). Measure the space between the edge of the full plywood sheet and the wall to determine the size you need. Cut a full board to that size with a circular saw, making the cut 1/2-inch shorter than the measurement so there is a space left there by the wall. Screw it to the floor as before.
- 5). Cover the rest of the surface of the floor in the same manner, with rows of plywood laid end to end. Stagger the starting size of each course as needed to ensure there are no four-way intersections between courses. Cover the whole floor.
Source...