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TL;DR: AFAIK there are no joist hangers that can be retrofit in a location where there's an existing ledger board without removing said ledger, right? Is there anything I should think about aside from adding blocking between joists, given the existing structure?

Full deal:

I have a house built in 1910ish. I think there were some fairly significant modifications to the structure early on. In any case, most of the 1st floor joists are riding on ledger boards.

Some of the joists have twisted or shifted (or both) over time. I suspect this is because of an external, shifted retaining wall (it's slated to be replaced too) and because of a significant area of water/insect damage that was repaired in the past. Some of the joists have, of course, split horizontally where the notches were made, and there are four or five in one corner that have pulled away from their attachment at the sill beam. (I haven't figured out quite what to do about that. It doesn't look like it's moving now, so I suspect this is a consequence of the insect and water damage in the past.)

Some searching online does not suggest to me that there are joist hangers designed to work around existing ledger boards (but I solicit pointers). I don't know it would even be possible to remove the ledger board without affecting the structure pretty badly, so I don't think that's the way to go. (This is just some stabilising work I'm trying to do, not a gut job, so I don't want to rebuild everything.)

I'm now thinking that putting blocking between the joists, to reduce the tendency to twisting, is all I can do. Am I failing to think of something obvious?

joist/ledger connection

you can sort of see the separation here

simpler case against interior beam -- hard to move wires

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    I'm having trouble picturing the situation you're trying to resolve. Is the sill plate interfering with access to the ledger? Can you add a photo or diagram? (Blocking will strength and stiffen the floor, so that's a good idea anyway.) – Hank Feb 23 '15 at 15:37
  • Very sorry I disappeared after this; that darned life keeps intervening. Anyway, the issue is that there's a joist and it connects to a supporting member (this is a problem both at a sill and at a beam, actually) where there's a ledger. I want to leave the ledger where it is, but take the load off the ledger/rabbet and move it properly onto the whole members. This can't be a completely unusual retofit problem, since I've had more than one house where rabbet/ledger issues show up. I'll add some photos. The photoing, however, has also led me to see some separation :( – Andrew Sullivan Sep 6 '15 at 1:54
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Simpson makes brackets that can be attached with joist hanger nails that are NOT joist hangers; I have them on the ends of my stair stringers. Most likley the:

L/LS/GA Reinforcing and Skewable Angles

Simpson L90

I suppose other companies make similar things, though to some extent SST is such a behemoth I don't know of any others in my local market. Anyway, if the ledger is carrying the bottom load, these will provide reenforcing for the attachment.

They also make flat reenforcing plates that could be attach across the splits to stabilize them, at least temporarily (which can be a few decades in house work, often enough...)

  • This is hugely helpful; thanks. But the only way I can see these could work is if I cut the existing ledger out or else bought the really short ones to do the ends only. I guess what I was hoping for at worst was one that did (say) L30 on one side and L50 on the other. That'd give the cutout over the ledger and at least would give end attachment better than what's there. Modifying doesn't seem engineering-sound. I like the flat plates, though, and may use those. Thanks so much. – Andrew Sullivan Sep 6 '15 at 2:04

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