How to Cut the Ceiling Frame of a House

A standard residential ceiling consists of either a joist system or a truss system featuring horizontal members that form the ceiling frame. If your ceiling has joists, you can cut one or more to install an attic fan, a pull-down ladder access or a similar fixture. Cutting joists in the ceiling frame requires the installation of headers that bridge the adjacent joists. If your ceiling frame is made from trusses, however, you can’t cut it without an engineer first determining how best to transfer roof load.

  1. 1.

    Measure rough opening dimensions on the ceiling and snap chalk lines to represent the dimensions. If you’re installing a pull-down ladder or attic fan, rough opening dimensions should be listed on the outside of the box or on an installation sheet. If you’re installing a used fixture, measure the backside, not including any trim and use that for the rough opening dimension.

  2. 2.

    Cut the ceiling drywall along the chalk lines with a sharp utility knife and remove the center drywall section. This will reveal one or more joists.

  3. 3.

    Make pencil marks on the joists you will be removing. This is best done from the attic. If you are removing only one joist, make a mark on each end, 1 1/2 inches wider than the rough opening. If you’re removing two or three joists, make the marks 3 inches wider than the rough opening.

  4. 4.

    Cut the marked joists from the top, using a reciprocating saw. Do not cut through the drywall. Remove the cut joist(s).

  5. 5.

    Measure the distance between the full joists on either side of the cut joists. These are trimmer joists. Standard ceiling joists sit on 24-inch centers and the space between them is 22 1/2 inches. If you removed one joist, the space between the trimmer joists should be about 46 1/2 inches. If you removed two joists, the distance will be closer to 70 1/2 inches. Always measure, however, because there can be slight variations in the layout.

  6. 6.

    Cut two boards to make single headers if you removed one joist, and cut four boards to make double headers if you removed two joists. Cut the headers from the same dimension of lumber as the joists. For example, if the joists are 2-by-6s, the headers should also be 2-by-6s.

  7. 7.

    Position a header between the remaining joists and at a right angle to both. Slide the header so the side fits snugly against the remaining stub of the cut joist.

  8. 8.

    Fit a framing nailer with 16d nails and insert two nails, evenly spaced, through the header into the end of the joist stub. Reach around the outside of the full remaining joist on one side and shoot two more nails through the joist and into the end of the header. Repeat on the other side of the header.

  9. 9.

    Attach another header on the other side of the opening in the same way. If you’re installing double headers, position the second headers flush against the first ones and nail them in the same manner.

  10. 10.

    Double the trimmer joists if you’re installing double headers. This involves installing an additional full-length joist on the outside of each trimmer joist. The ends of these joists must rest on a load-bearing wall or column. Insert two 16d nails evenly spaced every 12 inches to connect the new joists to the trimmer joists.

  11. 11.

    Install rough opening side blocks. The headers already form two sides of the rough opening frame, but the opening may be too large in the other direction. If so, measure the distance between the headers on each side of the drywall opening and cut two boards to fit. Attach them by inserting two 16d nails evenly spaced at 45-degree angles through the ends of the blocks into the headers. This is called "toenailing." Do this on both ends for both side blocks.

  12. 12.

    Secure the framing with perpendicular joist connectors. These are lightweight L-shaped metal brackets that fit in the corners where the headers and joists meet. The connectors have predrilled holes that require nails specific to the type of connector you purchase. Insert the nails into the holes with a regular hammer.