Things You'll Need
3 inch wood screws
Wood beams are used to support a bearing load from a roof or second floor. They can span as much as 20 feet, and many times they can be doubled as decorative pieces. Replacing a dry rotted beam is not a difficult task if you follow the tried and true methods listed below.
Support the weight above. Build temporary supports to brace the ceiling or floor at the point of support. A beam will always support the surface just above. Place a 2-by-4 stud on the floor at both sides of the beam. Have a helper hold a 2-by-4 stud on the ceiling or floor above and tap vertical studs in between for temporary support. Make sure the vertical supports are no more than 2 feet apart.
Cut the beam out of its resting place using a reciprocating saw. Cut through any nails at the points where the beam is attached to the surrounding framing. Make a cut in the center of the beam while a helper holds the two pieces into place. Using a pry bar, gently pry the beam loose from the ceiling.
Cut all exposed nails out of the way and make sure no additional wood needs to be cut out.
Check the framing that the old beam rested on to make sure it is still intact and well attached. You will be sliding the new beam back up onto the framing on each end of the beam.
Cut the new beam to length with the circular saw and the hand saw. You will make the first cut with the circular saw, however, it won't cut all the way through the thick beam. Use the hand saw to finish the cut.
Slide the new beam back into its original slots. Have a helper hold one end while you handle the other. Reattach the new beam with the 3-inch wood screws. Remove the temporary bracing and your new beam is fully functional.
Always be careful when cutting with power tools.
Wear protective clothing and gear.