Adjustable Steel Supports for Sagging Floors

What Adjustable Steel Support Jacks Are and When They Are the Right Call

When are steel supports the right call? Three situations cover most of what we see. A girder spans too far between masonry piers and sags in the middle. A pier has settled, cracked or been undermined by water moving through the crawl space, so the beam it carried has dropped. Or a run of joists spans farther than its depth allows, so the floor bounces or dips even though the wood itself is sound. In each case the framing needs another bearing point, and a post on a footing provides one without rebuilding the beam.

When are they not the right call? If the girder or joists have decayed, a post under rotten wood shores a member that still needs replacing. If the sag comes from the foundation wall or the sill plate, adding supports in the middle of the crawl space does not address it. And a post set on bare soil or a loose block rather than a proper footing will settle, so the footing matters as much as the post.

The work starts with the footing. Soil is dug out to firm ground and a concrete footing pad is poured, or a precast footing is set on compacted base, sized for the load it will carry. The post is placed on the footing under the beam, or under a new steel I beam that is first set across the joists. The threaded head is then turned to take up the load. Where a floor has sagged, that is done a little at a time over more than one visit, because framing and finishes above have adjusted to the sag and are stressed if it is removed all at once.

Expect a straightforward install compared with replacing framing, and expect honesty about how flat the floor will end up. Expect us to check the supports again on a later visit and adjust if the footing has bedded in. And expect the moisture correction to follow, since a pier that washed out did so because water was moving under the house.