I looked at a possible future project yesterday in a house built back in the early ’60s. It has a daylight basement and the floor joist are 2×6 on 16 centers running 24′ with a bearing wall half way between (@ roughly 12′). I’m looking for ideas to remove some of the floor movement. There is no visible sag but things shake when you walk around on the upper floor of the house. The basement is unfinished so I’ll have access from the bottom side and I’m still not sure how much demolition will be involved in the remodel so I’m not sure if we will get down thru the subfloor or not.
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Replies
2x8 is the minimum that should span this. Even tho you say no "visible" sag, it is hard to imagine no deflection in that, unless maybe really high quality Fir rough full size dimension. How hard did you squint? Did you use a straightedge or string to see if they were sagging? or just eyeball it?
In some situations You could handle this by doubling upp all those stringers but there could still be vibration. Sistering in 2x8s would be far best. If you do find that there is a sag, you should jack each existing joist to crown slightly before fastening the sister to it
Excellence is its own reward!
That was my original thought as well (sistering in 2x8) but I was attemptting to avoid all of the plumbing and electrical runs. Thanks for the input.
I think Piffin is correct - There's not much you could do with joists of that span except sister them or add another bearing under them.Duty, then, is the sublimest word in the English language. You should do your duty in all things. You can never do more. You should never wish to do less. [Gen. Robert E. Lee]
You'd need an engineer to calculate this and see if it makes sense, but maybe glue and nail 2x4's on the flat to the bottoms of the existing 2x6's to create an upside down "T" shape.... Kinda like a site built bottom half of a TJI. Is there mid-span blocking? If not, adding it should help.
-- J.S.