floor deflection due to over loading.

[Albion]

Howdy, i'm renovating 100 year old 2 story with attic. Basement girder is overloaded and off set 8" further then ( the width of the floor joists , 2by 10s or about 16" total from the girder) the load bearing wall above. That off set worked out as we installed and new spread footer &stud wall taking the load off the girder. So i'm wondering about the deflection in the framing members - do they straighten back from being deflected, sorry but tongue tied for better wording.

[Slaughter Construction Co]

Not likely, but exactly which framing are you referring too.

After a 100 years I doubt that there much spring left in those old boards.

[Albion]

I was concerned about the 2by10 floor joists. The flooring will be replaced next year so there is some time to see if any movement otherwise will add sub floor/ underlayment to even the floor out.

[dgbldr]

They have likely taken some permanent deformation (sag), but you don't know how much until you unload them (if ever).

They certainly can and do straighten out. Jack them up (slowly and with lots of jacks) a little past straight and sister with joists that have a slight crown the opposite way.

[Albion]

Howdy dgbldr, Thank you for the suggestion. We installed the wall 3/8" high to allow for shrinkage and incurrage the joists to even out. I had not thought of reversing the crown an sistering the joists great idea!!!

[dgbldr]

Albion, these are pretty routine steps. If you hadn't thought of that, chances are you don't do much structural work. I would suggest you consult a structural engineer to guide you until you gain more experience. It's cheap enough and structural mistakes are expensive.

[mike maines]

Albion, I wouldn't be too concerned about the girder being 8" out of alignment with the bearing wall above. Typically you can assume that loads will transfer down through framing at about a 45° angle, so with 2x10 joists you still have good support. That's a rule of thumb of course, your mileage may vary, etc.

It sounds like you're asking about the girder deflecting? Did you add additional support posts or sister on additional material to the girder?

[Albion]

Howdy Mike. The girder was 8" beyond where it should of been placed and overloaded and failing. I noticed the floor deflection and found the issues. So since there was room and this was the center wall of the 30' wide home. We installed a spread footer and transfered the loading off the girder onto a 2by8by 16" on center stud wall directly below the main center wall above. The deflection is in the floor joists next to the girder. I was curious about the wood fibers ability to straighten after the loading is no longer loading on them as before.

Howdy Dgbldr. Good point, i will never know enough but eager to gain from others. My dad use to call it "the goodie" the utility or tricks of the trade.

[Albion]

Howdy i re read my post an once again my wording is lacking. The girder is 17" away from the center wall above it. Rule of thumb the joists being 2 by10s would be a cantilever up to 9.25" from the center wall. I have the experience to correct the problem an have done so. The question i had was about the wood framing members-fibers potential movement. Sorry for confusing the whole darn thing. Next spring i will update if the wood members show corrective movement.

[mike maines]

Albion, if wood fibers are crushed or stretched beyond a certain point they won't spring back. If you were seeing significant deflection with the girder only 17" away from the load above, it must be a pretty heavy load and my guess would be that you won't see much, if any, spring-back. DGBLDR's advice is good.

[Albion]

howdy Mike Thanks, i was thinking back to how wood shake shinges fibers will flex back if a hail stone of a certian size strikes them. Wondering if on a grander scale what wood fibers would do. I had already pretty much figured it would not move much if any but was just pondering...

[mjr6550]

Based on your description and typical conditions I assume the joists have deflected near the center of their span. This has nothing to do with the deflection of the beam. Unless you have removed load from the joists they will not straighten by themselves. If you are replacing the subflooring the easiest approach to leveling the floor would be to sister joists or cleats to the joists.

[Albion]

Howdy 6550 thanks for the suggestions. The deflection is not in the center of the joists but your recommendations are good to know.