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Old 06-26-2016, 08:53 PM   #16
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Re: Rafter Vented Blocking and General blocking


Here is a drone shot of progress....moving slow thru this tedious stuff like venting but moving. Front and rear porches framing next..... Yard looks and is a lumber yard lol
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Rafter Vented Blocking and General blocking-dji_0065.jpg  
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Old 06-26-2016, 11:27 PM   #17
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Re: Rafter Vented Blocking and General blocking


"I do not think it matters if blocking is angled since it provides lateral rotation resistance in either position....your thoughts?"----- -- --Either or....One would need to plan for the correct depth of blocking when used plumb because you gain in measurement as roof is at a rake. 45* = 5" additional as you know when cutting rake in your case. Pretty hard to get such a wide board when using fairly wide rafter stock... OR, rip the tail overhang down from full depth rafter to hang a fascia board and those can get expensive really fast. OR- adding vertical blocking behind the vented blocking, over the wall plate- is the best solution. So, two blocks in each bay, again = more cost. Much easier to keep the rafter blocks at the rake (roof) angle, rather than plumb. Then both block/rafter are same stock, usually cut from bad (warp/cup/crook/split) rafters- or ripped down to fascia size.

The strapping would possibly negate the SE's meeting the shear flow for the roof diaphragm seismic zone... and you don't need that much ventilation. 2x fascia is optimum. The shear nailing of roof sheathing stops at the blocking/and above, hence the closer spacing at that edge of roof. Look for shiners from below after nailing the overhang, no point in leaving your signature there...lol. Drill the blocks low enough to clear required nail length through ply/meat above hole so nail is not visible in screened hole later. (and it would require another nail to meet spacing requirement since through into air rather than solid wood.

Gary
PS. NICE! Thanks for pic!
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Last edited by Gary in WA; 06-26-2016 at 11:30 PM. Reason: added ps
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Old 06-26-2016, 11:45 PM   #18
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Re: Rafter Vented Blocking and General blocking


Gary, my biggest concern was that not putting blocking plumb would violate code but it's not specified in code as to positioning, just as blocking for lateral force resistence (rafter rolling).

I've already got the vent holes drilled and blocking in at top plate and at ridge beam. I'm not sure what the code for nail penetration is for shear roof sheathing....will check. I actually used 2x8 stock for the blocking as it worked great with to block the 2x10 at the birdsmouth cut on top plate at the angle. Yes, buying 2x10 just to cut plumb would and cut the rake would have been brutal and more costly.

Did you see my question on the H2.5 simpson ties? I can't figure out if it's standard to use on both sides of rafters to top plate.
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Old 06-27-2016, 01:01 AM   #19
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Re: Rafter Vented Blocking and General blocking


We used to use a single (H-2.5), with the opposite hand one on the other end of same truss. Much easier to use an "H-1"; http://www.strongtie.com/seismicandh...ies/h_ties/p/h scroll 1/2 down. Use two only if one does not meet the shear requirement, call the SE and get it in writing, he/she should have called that out- pretty important...

Gary
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Old 06-27-2016, 01:07 AM   #20
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Re: Rafter Vented Blocking and General blocking


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Originally Posted by Gary in WA View Post
We used to use a single (H-2.5), with the opposite hand one on the other end of same truss. Much easier to use an "H-1"; http://www.strongtie.com/seismicandh...ies/h_ties/p/h scroll 1/2 down. Use two only if one does not meet the shear requirement, call the SE and get it in writing, he/she should have called that out- pretty important...

Gary
Gary...what is SE stand for? (don't laugh too hard). Plans only note to place 2.5 on each rafter. I think you actually clarified it....i read on simpson site that they make for left and right side......I thought it was for two on each end. Your truss note is what it is for. I should be fine with one.

Now to figure out how to frame the bastard (dutch) hip porches this week. Should be fun in 100 degree weather
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Old 06-27-2016, 06:58 PM   #21
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Re: Rafter Vented Blocking and General blocking


SE = my possibly wrong shortening of Structural Engineer...lol.

"Gary, my biggest concern was that not putting blocking plumb would violate code but it's not specified in code as to positioning, just as blocking for lateral force resistance (rafter rolling)."---------to get a minimum roof diaphragm, you need the closer nailing around the perimeter- overhang not included; eg; ------ well, I'll need to find another link. This shows the end wall nailing is closer -- pp. 22/30 and gable look-out and nailing, pp 30/37; http://www.awc.org/pdf/codes-standar...WG90B-0610.pdf

Gary
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Old 06-27-2016, 08:21 PM   #22
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Re: Rafter Vented Blocking and General blocking


Quote:
Originally Posted by Gary in WA View Post
SE = my possibly wrong shortening of Structural Engineer...lol.

"Gary, my biggest concern was that not putting blocking plumb would violate code but it's not specified in code as to positioning, just as blocking for lateral force resistance (rafter rolling)."---------to get a minimum roof diaphragm, you need the closer nailing around the perimeter- overhang not included; eg; ------ well, I'll need to find another link. This shows the end wall nailing is closer -- pp. 22/30 and gable look-out and nailing, pp 30/37; http://www.awc.org/pdf/codes-standar...WG90B-0610.pdf

Gary
Not exactly following the part about the "closer nailing around perimeter". The pdf you provided does show nailing of blocking to rafters directly, not top plate. I did see a post somewhere that someone was using a simpson tie of some sort to connect the blocking to the top plate, but definitely not code to do that.
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Old 06-28-2016, 03:42 PM   #23
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Re: Rafter Vented Blocking and General blocking


IF there is no special nailing required at the blocking from the SE, just follow code (probably similar);
"Although blocking may not be required for 2x10 and smaller rafters, there still must be a load path for lateral loads in the roof sheathing to reach the exterior braced walls immediately below the roof. The most direct load path is for
the roof sheathing to be edge nailed to blocking between each rafter. That blocking is then nailed to the wall top plate with three 8d nails per rafter space as prescribed in IRC Table 602.3(1). This load path is shown in Figure 6-4."----- See Fig. #5 also; https://c.ymcdn.com/sites/www.nibs.o...pter6final.pdf

Gary
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Old 07-04-2016, 02:05 PM   #24
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Re: Rafter Vented Blocking and General blocking


Quote:
Originally Posted by Gary in WA View Post
IF there is no special nailing required at the blocking from the SE, just follow code (probably similar);
"Although blocking may not be required for 2x10 and smaller rafters, there still must be a load path for lateral loads in the roof sheathing to reach the exterior braced walls immediately below the roof. The most direct load path is for
the roof sheathing to be edge nailed to blocking between each rafter. That blocking is then nailed to the wall top plate with three 8d nails per rafter space as prescribed in IRC Table 602.3(1). This load path is shown in Figure 6-4."----- See Fig. #5 also; https://c.ymcdn.com/sites/www.nibs.o...pter6final.pdf

Gary
Gary
I spoke to building dept and he confirmed the 3 8d nails but that that can also be done with the angled blocks I have so he was ok with what I have. I told him I could add simpson angle brackets to tie in also but he said that'd would be overkill in my situation so not needed.

I like to close my post subjects with results for other future diy builders reference.
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Old 07-04-2016, 04:50 PM   #25
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Re: Rafter Vented Blocking and General blocking


Yes, the three nails are for attaching blocking to plate as well as 2 at each end through the rafters. Also, the roof requires perimeter nailing into blocking (either plumb/square to rafters) to get full seismic/wind loads, ask locally. The perimeter is over the wall line below, hence the blocking.

Gary
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