A.Clayton DeKorne responds: Here’s one method that has worked well for me in the past. After stripping the siding off the wall in question, lag a ledger into the wall stud above the existing second-floor level. Then install temporary T-posts made from 2x6s nailed together at right angles, as shown in illustration A (next page). We’ve typically installed posts every two feet or so along the ledger, depending on the loads. Only one of the 2x6s in each post bears on the ledger; the other stiffens the bearing 2x6. Use plenty of nails to hold these 2x6 posts together, so the two pieces function as one stiff member.
Cut the posts long. Once they are wedged up under the ledger at a slight angle, we use a sledgehammer to drive the bottom end of each post toward the building. This lifts the structure slightly to take the load off the existing wall studs. To keep the posts from kicking out, screw a block down to hold the end of each post in place, much in the...
to read the full article.