How to Sister a Roof Beam

Sistering is reinforcing a weak or damaged roof beam by attaching a new beam alongside the existing one. If the beam is just sagging, you can sister the beam where the sag has occurred. If a part of the beam has broken, you must sister the entire beam.

Tools Needed

- Circular saw

- Sawzall

- Reciprocating Saw

- Hammer

- Drill

- Nailgun

Materials

- 2x4s

- 1-inch nails

- 3-inch screws

Step 1: Remove any drywall or other covering from the area around the damaged beam.

If the damaged beam is in the ceiling, you may have to remove some of the ceiling to access it.

Step 2: Cut the new beam to the same length as the damaged beam.

You can do this with a circular saw or a Sawzall.

Step 3: Place a 2x4 on each side of the beam.

The 2x4s should be flush with the top and bottom of the beam.

Step 4: Drill holes through the 2x4s and into the beam.

The holes should be spaced every 12 inches.

Step 5: Drive nails through the holes and into the beam.

Use 1-inch nails for this step.

Step 6: Screw the 2x4s to the beam.

Use 3-inch screws for this step.

Step 7: Repeat steps 3 through 6 for the other side of the beam.

Step 8: Replace any drywall or other covering that you removed.

Step 9: The beam is now reinforced.