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Old 07-27-2012, 05:42 AM   #16
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Old 07-27-2012, 07:30 AM   #17
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joist/rafter question


Does that answer the OP's question?
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Old 07-27-2012, 12:38 PM   #18
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joist/rafter question


if a picture is worth a thousand words, I guess the OP just got a short books worth. All framing from the 1st floor studs to the rafters (even to the other side) are ALWAYS in line, NOT offset. IF you look at the 1st photo I posted you will see how to layout the ridge, joists and rafters (ALL INLINE) 15 1/4 inches from front to back or left to right (doesn't matter) is where the rafter layout is typically on the ridge (both sides lay out the same way) I would have to charge for any more info than that...lol
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Old 07-27-2012, 02:47 PM   #19
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Ummmm... That can't work like that unless you have the joist running 3/4 crooked meeting on the bearing wall?? Ceiling joist are not inline with each other. They are always lapped and nailed together acting as a rafter tie. Therefore it would be impossible to line the rafters up with each other and also have the ceiling joist lapping on the bearing wall running straight.. Rafters ARE offset from each other. Also, the way your little picture is drawn with the rafter over the stud would be wrong. The first floor ceiling joist are offset from front wall to the back wall to achieve them being straight. The wall studs will match that to KEEP everything on the exterior walls inline. The floor joist, studs, and rafters will all be inline on the front wall, and the back wall as well, however at the ridge they will be offset mirroring the floor joist being offset on the bearing wall..
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Old 07-27-2012, 03:25 PM   #20
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Originally Posted by CopperClad View Post
The floor joist, studs, and rafters will all be inline on the front wall, and the back wall as well, however at the ridge they will be offset mirroring the floor joist being offset on the bearing wall..
Precisely
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Old 07-28-2012, 08:05 AM   #21
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Originally Posted by Maintenance 6 View Post
I've seen them offset from one side of the ridge to the other and it is such a small amount that it really wouldn't hurt anything. I've also seen them run off by 3/4" inch so that they met. The 3/4" out of plumb/square on a rafter is pretty trivial over the length of the rafter.
No reason in the world why that should happen. If it does that means they had no idea how to frame. And 3/4" of an inch does matter. Obviously you have never framed before to say that.
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Old 07-28-2012, 08:09 AM   #22
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Originally Posted by revlis_dyi View Post

So I was very confused when I was looking at our plans that called for overlapping joists in the room view of the building, but centered rafters in the roof view. How were we supposed to achieve staggered joists and directly opposing rafters?!
Very simple, the way the rafters are nailed on the plate is the same way they are nailed at the ridge. Same measurements.

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If the rafters can be offset, or even out of square by 3/4" just to make them meet, then things make more sense to me.
No...never. No reason in the world at all to do that. Rafters offset at the ridge, very simple! Only way they butt each other is with continuous ceiling joists.
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Old 07-28-2012, 08:32 AM   #23
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Originally Posted by revlis_dyi View Post
Sorry, yes I meant ridge board, not beam. My apologies. I had thought that you always had to nail rafters directly opposing to each other, and that's what some instructional videos on youtube were doing, even though the joists in their example were offset like I showed.

So I was very confused when I was looking at our plans that called for overlapping joists in the room view of the building, but centered rafters in the roof view. How were we supposed to achieve staggered joists and directly opposing rafters?!

If the rafters can be offset, or even out of square by 3/4" just to make them meet, then things make more sense to me.
Here's a drawing of the layout which has already been discussed.
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joist/rafter question-ceiling-joist-rafter-layout-6-28-12.jpg  
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Old 07-29-2012, 02:55 PM   #24
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If you will have it inspected by the local AHJ, it depends on your location (and his/her expertise). If you are under the IBC, (e.g. AR and NJ States) it requires “directly opposite each other” unless local amendments omit it; http://publicecodes.citation.com/ico...008_par050.htm

Check your State code here; http://www.reedconstructiondata.com/building-codes/

Interesting: http://www.inspectionnews.net/home_i...dge-board.html

C.joists “shall be cont. or securely joined where meet over interior partitions”, ----- 1-1/2” minimum bearing------ see chart footnote “e”; http://publicecodes.citation.com/ico...008_par051.htm

Under IRC, you may see it in the next (2015) Code Edition---LOL. Maybe then nail/staple “gage” will be spelled correctly…..http://www.google.com/search?q=Stapl...=hp&channel=np

Gary
P.S. Old habits die hard, I stand corrected: http://www.google.com/search?q=corre...=hp&channel=np
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Old 07-31-2012, 10:33 PM   #25
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Originally Posted by Joe Carola View Post
No reason in the world why that should happen. If it does that means they had no idea how to frame. And 3/4" of an inch does matter. Obviously you have never framed before to say that.
I said I've seen it hero, and on houses that are plenty older than you or I. And it must have been pretty common, because I can show you plenty of houses that were built that way.
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Old 08-05-2012, 10:53 AM   #26
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I said I've seen it hero, and on houses that are plenty older than you or I.
That's with t&g sheathing hero.

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Originally Posted by Maintenance 6 View Post
I've seen them offset from one side of the ridge to the other and it is such a small amount that it really wouldn't hurt anything.
Yes, it would with 4x8 sheets of plywood. So, again...no reason in the world to do that. Only an idiot would do that.
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Old 08-05-2012, 10:58 AM   #27
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Originally Posted by GBR in WA View Post
If you will have it inspected by the local AHJ, it depends on your location (and his/her expertise). If you are under the IBC, (e.g. AR and NJ States) it requires “directly opposite each other” unless local amendments omit it;
Gary,

That will never happen in this situation no matter what the code says unless the architects design continuous ceiling joists. If they draw them up like my drawing , the rafters can't oppose each other.
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Old 08-05-2012, 11:13 AM   #28
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joist/rafter question


if rafters are not opposing each other by a few inches a double ridge may be in order to take the force from the rafters.I've built plenty of double ridges ( even lvl ridges ) to take the force of lvl dormer rafters and what not. an inch and a half difference at the ridge is not to much though and the rafters still somewhat oppose at the edges of each rafter.
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Old 08-08-2012, 01:02 AM   #29
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Joe, I understand your concerns. Ask the local AHJ. You get to know the Inspectors in the field over time. I had a by-the-book Inspector that was rough. I learned code fast when under his area. I asked him this very point and he wanted them opposed when using a 1x r.b. Said to gusset (2x long enough to make code required number of fasteners each side over bearing wall) the c.j.'s and "nail them well" against pull-apart". With the rafters opposite, the c.j.'s (butting each other over bearing) lined up with an outside scab 2x (as per him, not code) as they broke over a wall. Think of the scab as a short c.j., fasten accordingly. Point is, rather than go directly against code, "ask the man" inspecting... my 2 cents.

Gary

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