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How to Frame Walls for a Basement Room

Partitioning off a below-grade space with This Old House general contractor Tom Silva

In this video, This Old House general contractor Tom Silva partitions off a below-grade space.


  1. Using 2-foot and 6-foot level, transfer the position of the overhead beam down to the basement floor. Make a plumb mark onto the floor at each end of the beam. If there are lally columns beneath the beam, draw plumb marks onto the floor between the columns.
  2. Snap a chalk line across the basement floor from one plumb mark to the next.
  3. Snap a second chalk line parallel to and 4 inches from the foundation wall.
  4. Use a power miter saw to cut to length the pressure-treated 2x4 bottom plate and fir or spruce 2x4 top plate.
  5. Set the top and bottom plates on edge and use a layout square to mark the locations of the wall studs; space the studs 16 inches on center.
  6. Lay the top and bottom plates flat on the floor and measure up to the underside of the beam to determine the height of the wall studs.
  7. Measure the wall-stud height in three or four spots, and then cut the studs to the shortest dimension using a portable circular saw.
  8. Assemble the wall frame on the floor by placing the studs between the top and bottom plates. Align each stud with the 16-inch on-center marks made earlier.
  9. Secure the studs by nailing through the top and bottom plates and into the ends of the studs.
  10. Stand up the wall frame and slide it beneath the beam. If necessary, use a hammer to tap the top plate flush with the face of the beam.
  11. Check to be sure the bottom plate is on the chalk line. Use the level to confirm that the wall is plumb, then nail up through the top plate and into the beam.
  12. Secure bottom plate to basement floor using a powder-actuated nail gun. Shoot one nail between each pair of studs.
  13. Repeat the previous steps to frame, install and secure the next wall. Be sure to maintain the 16-inch on-center stud spacing, and check the wall frame for plumb before nailing it to the beam.
  14. If you encounter an electrical panel, frame a wall section with a doorway in it, and stand it up in front of the electrical panel. When the wall is finished, hang a door to conceal the electrical panel, but provide easy access.