I’m doing a basement repair where a load bearing wall with a 3’0″ door was removed and 12′ of wall with it. The homeowner did a header which is now sagging and being replaced with a glulam. He’s putting in suspended ceiling after these repairs (the bottom of the floor joists are 9’2″ off the floor). The house has been settling into itself for two years and I’m just now done jacking it into place. But there’s a sag at the mid span of the floor which is right in front of the refrigerator in the kitchen above. VERY apparent there’s a problem there… The floor system is 2 x 10 on 16″ centers and spans almost 14 feet.
Without being an engineer but having thought this out, here’s what I’m thinking of doing. If you have ideas, good or bad, please share…
1) Place temporary beam below sag and jack floor framing to 1/4″ above its normal position.
2) Screw and glue a stiffback (2×4 & 2×6 on edge in this position along the length of the sag and extend two joists past each end. In this case, about 12′.
3) Cut X bracing out of 2×4 where it extends from the corner of the subfloor/face of the joist and runs diagonally to the bottom edge of the stiffback at the joist center for each joist. It may be overkill but I’m going to plow out 18 2 x 4’s to make tight braces with a lap joint. Jointery will be critical for this whole thing to work…
4) Glue and screw the X bracing to face of stiffback on both pieces of stock as well as into the joists making sure all joints are tight and full contact.
5) Glue and screw plywood skin to X bracing along entire length of braced area.
6) Let floor structure back into place while glue is still wet and keep supported for two or three days.
Think it will work? I hope this one makes sense and not too long winded. Weird problem where a post isn’t viable. Thoughts and comments are totally welcome…
Thanks,
Jerry
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Replies
Over the years there have been MANY threads about beefing up sagging floor joists. There have been a heck of a lot of wild suggestions made as to how to fix them.
I don't ever recomemnd anything that I don't know for sure will work. What you're doing may or may not make a difference. I kinda doubt it will.
I'd go with something you KNOW will work - Like sistering new joists or adding a beam.
If I understand the situation correctly, fifteen feet of a load bearing wall was removed and the homeowner tried to carry the load with a home made header!!??
You don't say how much sag you're trying to correct, but this sure seems like a place to get a structural engineer involved. Your planned "fix" may (or may not) do the job and you'll be on the hook if it doesn't. Getting an engineer to design a fix (or at least sign off on your plan) seems like cheap insurance in the long run.
It was actually 12' of wall removed (door was within that area) and is now resting on a header which I'm changing out to a glulam. The sag is about 7' from the beam location and is roughly 1-1/4" at its lowest point. I did a point load post and raised it up but the post has to go away by the end of the process. That was what got me to thinking about building a tension type suspension structure.
You're entirely correct about a structural engineer being needed. Budget isn't allowing that however. So the next best thing was present it here and get ideas. Some good ones so far... I have to check the mechanicals a little closer to see how many circuits and water lines would be involved with doing any sistering or steel plates. All in all, a good challenge...
If it doesn't work, you will be setting yourself up for a lot of work if it has to be redone. Are you sure you can,t get a couple of 2X10s sistered in there?
I would not rely on glue in this sense. The glue may have some structural properties, but that does not make it a reliable structural element.
Having said all that... Here is one method I have used to raise a sagging depression in a floor:
Cut the subfloor out in the area to where the floor is acceptably level. Sister up some lumber on the joists, but raised high enough to level the floor when you reinstall it. This will not remove the sag, but will give you a level floor above. If you can afford to sister up with more 2X10s, crown up, it should prevent further sagging.
Flitchbeam! Get a 1/8 inch steel plate 9 inch wide by as long as your span if you can. You will likely be limited to 10 foot long.
Jack up and support the joist with temporary columns. Drill the plate with a "W" pattern of 3/8 or 1/2 inch holes for bolts on 12 inch centers. Sandwich the plate with a 2x10 sister. (Use the plate as a drill guide (best done in place)). Bolt the sandwich together.
You won't believe how stiff a joist this assembly is until you make one.
I'd try it if I was getting paid.
Let us know how it helped out Okay?
blue
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