Sagging Floors

I’ve read many posts questioning the possibility of correcting sagging floors.

Over time floor joists may deflect from straight to reflect a lack of support in some way. This can be caused by any number of reasons.

Once these floor joists have over time adopted a new shape (banana??) they are stubborn about resuming their original straight shape.

I have gut renovated homes including taking all plaster, ceilings etc out. In terms of straightening joists, this would be a best case scenario.

What I have found is you can lift the joists given enough strength, but you can’t make’em straight again. The banana is now in a new position, but it isn’t straight.

Best practice:
1. Make strong support walls
2.Sister joists if you want level floors.
The floors have to be open, but it’s faster, cheaper, and the results will be secure and straight.

3.I have found that it helps to bite the bullet and sister both sides with an appropriate mixture of 2X6/2X8/2X10’s, thru bolted.

4. I sister both sides because old joists don’t go straight left to right, and the spacing can range from 18″ to 27″. The 1.5″ thckness on both sides of every joist reduces the largest spacings to a manageable width to bridge with tongue and grooved plywood subfloor.

None of this applies if you are trying to preserve existing flooring, as the above assumes floors removed.

Good Luck

Bruce