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floor joist hanger and separation

Found a leak in our second floor bathroom which destroyed the existing OSB subfloor and had to remove - giving me the opportunity to remodel it into a more modern master bath (fun). Discovered what appears to be two issues that needs to be addressed -

  1. The floor joists don't seem to be fastened to the hangers. If I kick the tops of them, they do move a little so they're not fastened at all to the rim boards.

  2. The marriage joint (is a prefab house), seems a little separated to me. There isn't any evidence that its widening (no cracks in cinder block foundation or first floor walls/ceiling, so maybe it was just wide when the house was built (approx 30 years ago).

My plan for 1 was to support each joist, pull the existing hanger and mount a new one. There are some joists that have 3" drain cutouts, which I dont need, so was going to sister some of these on a double hanger.

For 2, I'm kind of stumped. I could just fill the gap with some foam and hope its not a symptom of a larger problem. I was also thinking about putting in lots of 1/2" grade 8 bolts connecting the marriage joint and hope this prevents the joint from widening anymore if its happening very slowly? But this could also make a bigger problem down the road maybe (like maybe this would cause the floor joist being ripped out of the rim board if it did move a little).

Wondering what people's advice would be on this and if I'm thinking about it in the right way.

bcee987
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  • When ripping out the old flooring, did you notice any joints being further apart than the rest or nails that seem bent/at an angle? The problem is you do not know if that joint was ever tight and moving or it has always been like that. Usually to recommend putting tape or something over the joint and check over months, but you want a bathroom before that is helpful. – crip659 Oct 17 '23 at 18:55
  • I removed more subfloor following the joint and found a lag connecting the two that appears intact. Guess Im leaning towards it was always like this. Hard to imagine it separating and not breaking the subfloor – bcee987 Oct 17 '23 at 19:16
  • The typical spec for acceptable joist notches is the IRC's: https://codes.iccsafe.org/content/IRC2015/chapter-5-floors#IRC2015_Pt03_Ch05_SecR502.8 – popham Oct 17 '23 at 22:18
  • 1/2" Grade 8 bolts? If you must have something with a spec sheet, then 1/2" A307s or 1/2" grade 2 bolts would provide the same performance. All steel bolts will have the same modulus of elasticity, where the wood under the washers will fail in bearing long before A307s fail. – popham Oct 17 '23 at 22:46
  • Can you quantify the gap in the marriage joint? My eye sees an elevation shift and tiny gaps in the neighborhood of 1/32". Are those framed surfaces at the same elevation? Or is there an elevation shift? – popham Oct 17 '23 at 22:55

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