fixing floor sag - piers

manunderstressDecember 7, 2011

I've read a bunch of other threads on the floor sag issue but still have some questions... Have some sag (joist sag) in two rooms due to long spanning joists, had an engineering group take a look and they recommended additional piers on concrete footings, and a beam perpendicular to the joists to shore them up. I'm thinking about using something like the Ellis screw jack for the project, both for jacking AND as permanent supports, as a couple of jacks should be able to handle the load. The biggest pain by far seems to be pouring 12x12x12 inch footers in the crawlspace. Ugh. So I am wondering if there are any pre-cast footings available to do the job, something that just sits on the ground. After all, this is not huge load we are talking about...ideas?

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If using a screw jack, it must be one that is suitable for permanent installation.

Footers that sit on the ground do not provide uplift resistance. This may have to be added.

Check on both these issues with the engineers you consulted in the first place.

    Bookmark   December 7, 2011 at 1:36PM
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Precast footers should be available, yo may have to look around.

Most screw jack columns need some tack welds for permanent use.

Uplift should not be an issue for supplemental support.

    Bookmark   December 7, 2011 at 3:53PM
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The engineers should have given you a complete solution not just general advice.

    Bookmark   December 7, 2011 at 6:54PM
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Most screw jack columns need some tack welds for permanent use.

For a new home, a steel supplier once shipped me four permanent posts with screw jacks top and bottom. The bottom was fine; buried in the concrete floor, there was adequate lateral support. But two-three foot straps had to be welded on each of the tops--from the post to the plate. As noted above, your posts are supplemental, so such details may not be necessary. The engineering firm should have provided you detailed drawings.

    Bookmark   December 7, 2011 at 8:02PM
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I should have clarified- didn't *hire* engineers, just got a bid. Being that this is supplementary support/stabilization effort, and I'm not messing with lifting the foundation, I'm inclined to give it a shot myself. Guess that's why I'm digging for advice here...perhaps it would be worth it to get a proper engineer to draw up plans? I doubt I could do worse than some others have tried down there though...supplementary "supports" consisting of 4x4s stuck between the bare earth directly to a joist!

    Bookmark   December 8, 2011 at 12:30AM
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You could try a continuous 2x4 knee wall of pressure treated lumber, running perpendicular to the floor joists, resting on a P.T. 2x10 sub-plate on polyethylene on a few inches of gravel. The polyethylene should cover the entire crawlspace if it is bare earth. The floor would be raised as the studs are hammered into place under each joist, assuming the permanent deflection is not too great.

    Bookmark   December 8, 2011 at 3:34PM
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