Balloon Framing Question

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  #1  
Old 07-24-09, 09:28 AM
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Balloon Framing Question

I'm renovating my 90 year old house, which is balloon framed (each floor has a double top plate but no bottom plate. No rim joists). The 2nd floor ceiling/attic floor is 2x4s right now. For obvious reasons, I'm replacing them with 2x8s. I'll be blocking in the middle of the 8 foot spans and twice on the 12 foot spans. In the middle of the house where they rest on a beam, I can easily put a rim joist or two there and I'm comfortable with that.

My question is on the outside walls: Where it intersects with a vertical attic wall with studs, I would rest the joist on the top plate and use 4 16D toenails (or 2 toenails and 3 through-nails if it is next to a stud), but I'm wondering if I should do something to help prevent twisting at the ends. I was thinking if I installed blocking at the end, next to the top plate but not resting on it, it would also give me more attachment surface for the sheetrock, rather than having to rely on 16" spacing along the edge, and also prevent twisting. Or should I try to put blocking between the studs resting on the plate, kind of a faux rim joist? The other option is mounting a 2x8 to the studs and using hangers for the joists, but these attic studs aren't secured very well at the top, not sure I'd be comfortable with that.

Where it intersects with the bottom of the roofline, can I just use 2 toenails to the top plate and some nails to the rafters (how they are now) or is that too much strain on the rafters? I believe they make some sort of hurricane tie for this but I believe it is for newer framing styles. I'll have to cut an angle into the end of the joist regardless but shouldn't be steep enough to weaken it, certainly still be stronger than the 2x4s. The joists are set up now so they always fall right next to a rafter and are nailed into them, so figured doing the same was the way to go.

There will be some storage space and a furnace (forced air, not that heavy) up there, but it won't be living space.
 
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  #2  
Old 07-24-09, 03:49 PM
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I'd bear them on the plates and blocks in front, closing the gap from fire. 3-8d nails req. as per code. You'll love this site, scroll up and back, next, ...... explore it.

Single Family Residential Construction Guide - Nailing Schedule

H Seismic and Hurricane Ties
It comes in right hand and left for side of rafter.

Be safe, G
 
  #3  
Old 07-26-09, 07:30 PM
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Yeah I have that nail schedule printed out, it is handy. I was under the assumption that the 3 8D was when using a rim joist, as that will be nailed every 6 or 12 inches or whatever it is. 3 8Ds seems pretty light if its the only thing holding a 2x8x12 down on either end.

Not sure if the blocking would really add any fire block, the top plate takes care of that. But it does seem that it would add some extra lateral strength to prevent twisting and also let me do more than 16" spacing on the sheetrock screws around the perimeter, though its not really required.

Thx for the input. Would be easier to just build this place from scratch :-)
 
  #4  
Old 07-27-09, 04:07 AM
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"Would be easier to just build this place from scratch :-) "
You wouldn't believe how many times that has been said!

Bud
 
  #5  
Old 07-27-09, 10:13 AM
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The blocking is required for lateral resistance to turn-over. It is also required for fire stop between floor/upper wall, unless you have a bottom plate.

Solid 2X nominal blocking is required at ends of joists and over all bearing points. Blocking may be omitted where ends of joists are nailed to a header or rim joist. Joists 2 x 12 or larger must be blocked at intervals not to exceed 8'-0". Joists must be doubled under parallel bearing walls above.

Be safe, G
 
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