Expert: Bruce E. Johnson - 10/7/2010

Question
I need to replace a 30 ft. section of baseplate and rim board. The base plate and the joists at the end where it meets the baseplate are rotted. Knowing that I need to jack the house up slightly, I was looking for the best way to jack up the house, replace the rim and plate and then marry new wood onto the joists that are rotted. What would be the best prcedure for this?  

Answer
Hi Jim, it all depends on what kind of access you have and what direction you are going to attack the problem from.  If you have a shallow crawl space and are working from underneath the house then your shoring will have to be back far enough to allow you to get at the joists from underneath.  If you are opening up the wall from the outside and can access the rotted wood from the exterior then your shoring can be closer to the wall.  At any rate this is one way to do it:  Call a house moving company and see what they would charge to jack up and shore the side of the house you need to repair.  You will find that they are reasonable and can do the shoring work probably cheaper than you can buy the materials to do your own shoring with and they can do the entire 30 feet at once.

If that idea doesn't work for you and you want to do it yourself you will need some wood for beams.  4x6 will work.  And some post material. 4x4 are perfect.  And something to set the posts on.  Three or four layers of 3/4" plywood cut into 2'x2' squares make a decent temporary post foundation.  Your posts can be up to 6' apart for a 4x6 beam.  It would be best if you chose a 4x6 beam that was at least as long as the lengths of sill plate you are replacing.  That way you can support and remove a complete section at a time.  In other words if your sill plate is in 12' lengths then you should use 12' 4x6 to match the length of the sill plate.

First off you get the beam in place under your joists and your support plywood layers for the posts.  Using two layers of plywood as your initial support layer, measure your posts to length and jam them up under your beam so that they push the beam snug to the bottom of the joists. At this point you may want to nail some small plywood gussets to attach the beam to the post and keep the posts from fall out when you start jacking.  Start at one end and begin to jack up the beam.  Have a good supply of wood shims at hand and only jack up the beam a quarter of an inch and slide some shims under the first post until it is snug.  Release the jack and move alongside the next post and repeat the move until you have all three posts up a quarter and then work your way back starting at your last post and jacking that one up another quarter and shimming it etc.  After this run your joists should be up enough to get the sill plate out.  If not keep repeating the moves until you have sufficient clearance.  Complete one section of joist repair and sill replacement and move on.

Having a sawzall handy to cut nails and stuff is important.  Also, if your sill plate is bolted down from embedded bolts you will need to slot your new sill plate so you can slide it into place around the foundation bolts.  Then you can use oversized bolt washers to clamp the new sill down with the existing bolts.

I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com