DIY Network

Leveling a Floor True up the floor, and everything else gets easier. From "Wasted Spaces" episode DWSP-307

Level the floor for a professional makeover.

Mark and Molly's combination closet/dressing room has lots of space, thanks to a long-ago addition by a previous owner. But even though the addition made the space larger, it didn't make it level – the floor slants severely.

Karl helps the couple get everything back on the level so they can install new carpet tile and storage including a custom laundry sorter and hidden in-floor storage. He also helps them get rid of another problem left by the addition by removing a partial wall that sticks out into the room.

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Leveling a Floor

Tools: safety glasses table saw framing nailer compressor screw gun measuring tape 4-foot level carpenter’s pencil gloves

Materials: screws framing nails 2x10s (8' long) construction adhesive 3/4" sanded plywood

• Measure the drop. Lay a long level "downhill" on the floor, with one end of the level on the level part of the floor and the other end at the lowest point. Raise the lower end of the level until the bubble is centered, then measure the distance from the bottom of the level to the floor to find the depth of the dip.
  

  	Figure A
  	Figure B
  	Figure C

  Tip: If the level isn't long enough, lay a flat board along the floor with a level on top. Raise the board until the level reads true, then measure from the dip in the floor to the bottom of the board.

• Cut first leveling strip. Cut a leveling strip – a very long triangle – from a 2x10. The triangle should taper from the out-of-level measurement down to nothing. Several long triangles like this one will be attached to the floor to bring the surface up to level (figure A).

• Fit the leveling strip. Position the leveling strip on the floor and see if the top edge of the strip checks out as level. Adjust the strip as needed. When complete, this will be a spacer that bridges the gap between the old floor and the new, level surface.

• Cut more strips. Since this floor slants on just one side – and slants the same amount all along that side – Karl could use leveling strips that were the same size. To do this, simply cut several leveling strips the same size as the original strip. If the floor slants irregularly, cut strips that bridge the cap at each floor joist.

• Attach leveling strips. Use screws to secure the leveling strips to the floor every 16 inches. Screw the strips into the floor joists or subfloor (figure B).

• Install plywood subfloor. Run a bead of construction adhesive along the top of each strip, then install 3/4" plywood on top of the strips to create the new floor surface. Nail the plywood in place with a framing nailer (figure C).

• Add hidden storage. If installing hidden in-floor storage boxes, as Karl did in this episode, this is the time to cut the holes in the subfloor to accommodate them. Otherwise, finish the floor with carpet tiles or other surfacing as desired.