Was thinking about eliminating the rim/band joist on a house I am about to begin framing. I’d replace it with a quasi balloon framed approach, taking the studs and top plate up to where the top of the rim joist would be. I’d use top flange joist hangers to hold up the i-joists. The 2nd floor subfloor would run out onto this top plate. Everything is stack framed 2×6 @ 24″ o.c. – The second floor studs line up with the lower wall studs, joists are in line with studs.
Any reason this won’t work?
Replies
It would work for me.
I'm guessing you are interested in eliminating the band joist for insulation purposes? Or, is it for shrinkage issues?
FKA Blue (eyeddevil)
The shrinkage issue occured to me, didn't think about insulation. I'm thinking it would require longer studs, and wall blocking at the top of the ceiling. What's up with the insulation?View Image “Good work costs much more than poor imitation or factory product” – Charles GreeneCaliforniaRemodelingContractor.com
The longer studs wouldn't necessarily be a bad thing....going from 8's to 9's or 9's to 10's. Instead of 4" of insulation, he'd have 5.5".There would be a draftstop issue that he'd have to address. That could be done many ways so until I understand his motivation, I won't hazard a guess. FKA Blue (eyeddevil)
I don't think it will meet code for resistance to lateral loads, first of all.
Also, the flanges of the joist hangers (top mount have a certain amount of thickness usually) might kick up the subfloor a bit. So why do it?
Jeff
What do you mean, Lateral loads? FKA Blue (eyeddevil)
Uh ... like when the wind blows ;o) Basically all of the horizontal forces acting on a structure, including earthquake motion.
Lateral load resistance is one of the primary purposes of rim joists and (lack thereof) one of the major weaknesses of balloon frame.
Jeff
If rim joists are so critical, why aren't they required on single story roofs? Lateral resistance is created with let in braces or plywood sheathing. I don't see how a structure gains any strength with a rim joist running around in the middle of the two walls. It seems like just the opposite would be true.I'm no engineer though...so please, someone enlighten me. FKA Blue (eyeddevil)
What about fire blocking?
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I'd replace it with a quasi balloon framed approach, taking the studs and top plate up to where the top of the rim joist would be. I'd use top flange joist hangers to hold up the i-joists. The 2nd floor subfloor would run out onto this top plate.
Any reason this won't work?
It will work.The question isn't why it wont work, the question is, why would you want to do that and waste all that time? Couple thoughts already without knowing why you want to do this.
1) You would have to cut every stud instead of using precuts(no big deal, do it on custom work all the time) but this isn't the case, or maybe it is.
2) Hanging joists for no reason wasting time and money for hangers.
3) Have to install fire blocks on every single stud for no reason.
Everything is stack framed 2x6 @ 24" o.c. - The second floor studs line up with the lower wall studs, joists are in line with studs.
That's should to be done no matter what way you frame.
The motivation was to simplify by eliminating an added framing element.
- It is custom and I will need to cut every stud anyway.
- Fireblocking would need to be installed. The plans do call out for a mid height solid blocking anyway, but this probably would not suffice for fireblocking as I'm supposing it would need to be at the top of the wall to qualify.
- Joist hangers are an element that I would now have to add back in. I don't know that cost tradeoff between 100+' of engineered rim board and ~38 joist hangers and associated labor differences.
- Yes, stacking should always be done, but I have yet to see a house around here (Asheville, NC) that uses stack framing of any nature, whether 16"oc or 24"oc.
I probably don't gain much, or even lose a little with this idea, so I am going to shelve it and use a rim board. Thanks to everyone for poking holes in the idea - that is what I needed.
JD