Placing a sub floor over a concrete is one way to help you finish off your basement. The sub floor will act as a level base and not be as cold on the feet. When you’re getting ready, prepare the surrounding area properly, ensuring that water will not seep through to the concrete underneath.

Map It Out
Plan your renovation by drawing it out on some graph paper, using each square as per square. Calculate the number and length of 2″ x 3″ strips of wood required for the area of the basement. Then, measure and calculate the length and amount of 2″ x 3″ pieces needed for sleeper, which you will nail on 40 cm (16 inch) centres. Lastly, measure the number of 4′ x 8′ fibre or plywood pieces that you will need to cover the sub floor.

Waterproofing
Place 6mm polyethylene on top of the concrete to act as a barrier and prevent humidity to the ground floor. Be sure to leave about 4 inches of polyethylene along the side of each wall. This will prevent any further humidity damage.

Note: Instead of 6mm polyethylene, you can also use a 15 lb felt paper.

Framing
Build a sub floor frame throughout the basement along the floor. Using 2″ x 3″ strips of wood, place them directly on top of the 6mm polyethylene along each wall of the basement. Now, using a 16-inch centre, place sleepers throughout the frame, making sure that the first sleeper is 16 inches from the wall with the rest being 16 inches apart. Be sure to lay the sleeper in the direction to the smallest area of the room.

Making it Level
Make sure that the sleepers are level. You may have to use shims in order to get the entire floor leveled - this is very important. After they are leveled, anchor them to the concrete floor using a concrete drill or ramset. Allow a distance of 12 inches between each nail. Cut off the excess polyethylene with a utility knife. Using a pencil, mark the placement of each sleeper along the basement walls as a template for when the sheets of plywood.

Laying It All Down
Before laying down the fibre or plywood, ensure that they are 5/8″ thick. Also, apply a strong adhesive to each sleeper throughout the basement prior to laying the sheets down. Make sure that you stagger the plywood sheets from one sheet to the next, creating a stronger floor area. Place the sheets perpendicular to the sleepers, making sure that they are parallel to the shortest wall. Now, using the templated pencil marks, screw in the sheets of plywood to the sleepers and framing. Space out the screws approximately 12 inches while using 1-1/2″ wood screws.

You will be able to find or rent all the tools and materials at your local building supply store.

Chris Paulsen
cpaulsen@homerenovationguide.com