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sikkensuser 10-21-2010 05:58 PM

joist replacement
I'm looking to replace a few joists over a shallow (20") dirt crawlspace. I'm having some trouble jacking up the adjacent joists as the wood is now somewhat/considerably too brittle to remove the old one and fit the new one in without crushing the old joists. What is the best way of dissipating the force of the jack over a larger area to raise the floor above sufficiently to position the new joist?

placing a long 2x8 parallel and flush with the sub-floor next to the joist to be removed and jack up both ends in tandem maybe?


GBR 10-21-2010 07:03 PM

I hope your dirt is covered with a plastic vapor barrier.

What exactly, is wrong with the current joists? This will determine my reply....


sikkensuser 10-22-2010 05:05 PM

Their has been some localized rot on the joists where they approach the copper plumbing lines (Sweating).

Yes, their is a vapor barrier on top of the soil.

GBR 10-22-2010 09:29 PM

I would leave the old ones alone and install new ones next to- and nail, 16d at16"o.c. at each edge, 2" in. Rip a 1/4" or so, out of the bottom of the new ones only where hitting the bearing areas. Glue and install the new after jacking, if necessary. Jack under the new on each end after tacking it to the old one. 2 nails on each end to keep it from tipping when jacking, yet not enough to stop it from raising to height of the old one. Then drive some hardwood, not cedar, shims in at bearing. Nail it off.

I would wear a mask and clean out the rot/mold spores to prevent another occurrence if it gets wet again: UMass Amherst: Building and Construction Technology Wood Myths: Facts and Fictions About Wood


nealtw 11-04-2010 05:40 PM

You need air flow between poly and floor. If properly vented this water should not have caused any problem.

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