GF joists over ‘internal’ cavity wall

[OwenF]

I’ve taken down a cavity wall that separated the kitchen & attached garage. 
Planning what to do with bringing new joists in garage to meet existing. Image below shows existing joists bearing onto what was the inner leaf.

New joists will be coming from ledger plate off to the left.

Originally thought I’d lap them ~100mm beyond the inner leaf. This is going to throw off chipboard ends landing on a joist part way through the room.

 

would butt ending old and new be crazy? Bearing in mind that new would have 150mm bearing on the old outer (garage) leaf?

 

[ProDave]

I don't see the issue.  the first strip of boards you lay might partly miss the joists, but it is not imperative that the joints land on a joist.  You can see the board joints in the photo are not landing on a joist.

[OwenF]

Good point. And I’ve just realised if I was really bothered I could rip the board width down to coincide with the offset at the lap and re-stagger the boards (albeit loosing the T&G so probs not worth it)

I notice NHBC say max overlap of 100mm beyond wall (for a single skin). I presume this is to avoid the free end deflecting up and interfering with floor.

I’m technically bearing on a 300mm wide wall. I guess I won’t have problems. Again, if worried I could remove outer block at joist locations to keep bearing to 100mm

perhaps overthinking it