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On a single story 2×4 frame house, what size bottle jacks should I use to lift up (slightly) the floor joists?
I plan on using a 6″x6″x10′ to support the joists while replacing the sill. Will two 8-ton bottle jacks be enough?
Any tips you can share for doing this repair work?
Thanks in advance
Phil
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Replies
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Phil,
8 tons should be fine.
Ed. Williams
*Could I suggest you not use bottle jacks ? Two reasons, really. Hydraulic jacks can leak, and settle on you at the worst possible moment. Second, they don't have a large surface area to bear on. I once saw some guys jacking up a cabin with four of those. The board split at the top of one of the jacks, and the whole cabin fell. Fortunatley, no one got hurt. But, please be careful.
*I've just done similar work this summer and used a minimum of 4 12 ton jacks per 12' joist under a two story. I think you can still find a picture of this under the thread "this old house". I used a steel beam and two jacks as the main lifters and two as back-up. You absolutely must have a 3/8x4x4 steel plate underneath any 4x4 post on top of the jack rod otherwise the post will split as you jack and you could find yourself in trouble with flying timber. Do not ever jack more than 1/4" withouth shimming up so that in the event the jack does buckle out it doesn't have enough room, or pressure, to fire across the room. This is dangerous work that should be approached with every conceivable precaution.
*I do a lot of old home restoration, and here are my thoughts.1. Your jacks are fine.2. Use steel for a backing plate for the timbers.3. Use cribbing (4x4 blocks) to hold the sill in areas in whicdh you are not jacking.4. Go slow if it is your home. Warn the homeowners if this is a commercial job that drywall and plaster will crack. 5. Of course, pour a new foundation and stem wall, and use a sill sealer/sill fabric to prevent rot. Consider tie downs and interior shear wall construction. Simpson has a whole product line on shear walls.JLC had a great article on the subject about 2 years ago. Perhaps a phone call could access the archives.
*Thanks everyone.Scooter, I'm not sure what you meant by, 3. Use cribbing (4x4 blocks) to hold the sill in areas in which you are not jacking.Can you please elaborate ?Thanks again,Phil
*This may sound like a given, but cribbing is simply a support, to take the weight off the jacks when they are not being used.Take a bunch of 4x4 posts, and cut them into 16" pieces, and stack them on top of eachother to build a stackable pier for support. You could also use 10" concret blocks with 4x and 2x and 1x lumber for shims.