Remove any perpendicular 2 inch blocks at either side of the rafter with a nail bar and framing.
How to sister roof joists.
In situations when sistering damaged floor joists with lumber of similar dimensions it can be easy to notch and slide the sister board into place.
Take some extra time and jack the damaged area up so that the new lumber doesn t need to be.
Nail 10d or 16d common nails through the sister and into the existing joist.
Make two rows of nails spaced 16 inches or less apart along the length of the sister.
Fasten the sister joist to the existing joist with three nails every 16 in.
However doing this does not fix the slant that the floor has taken since the old joists got damaged.
Call in a structural engineer.
How to make structural repairs by sistering floor joists sistering floor joists.
In these cases the overlapped joists help tie the framing together by combining the rigid members over a beam.
You should overhang at least a couple of feet on each side of the beam.
Measure the overall distance of the existing rafter from the ridge board to the outermost point where the rafter.
Nail the new joist in place.
Run the rows parallel and an inch.
How to sister a roof rafter 1.