SST Twist Strap at Every Roof Rafter?
SST Twist Strap at Every Roof Rafter?
(OP)
Hello all:
Would like to know your take on the need for roof rafter to wall straps at every rafter. I am just getting back to this after a few years of calling them out on the plans at every rafter. I believe that the load (20 psf uplift minus dead load) does not justify the need. Would like to know what you guys use. In this area wind controls. This is for residential frame construction and the roof slopes vary from 4:12 to 12:12. What triggered me the question is anchorage to foundation per code is @ 48" o.c. According to my numbers straps every third rafter would suffice.
Regards
Rarebug
Would like to know your take on the need for roof rafter to wall straps at every rafter. I am just getting back to this after a few years of calling them out on the plans at every rafter. I believe that the load (20 psf uplift minus dead load) does not justify the need. Would like to know what you guys use. In this area wind controls. This is for residential frame construction and the roof slopes vary from 4:12 to 12:12. What triggered me the question is anchorage to foundation per code is @ 48" o.c. According to my numbers straps every third rafter would suffice.
Regards
Rarebug






RE: SST Twist Strap at Every Roof Rafter?
RE: SST Twist Strap at Every Roof Rafter?
RE: SST Twist Strap at Every Roof Rafter?
Also, in our area, anchorage to the the foundation is only req'd at 6 ft. O.C. - even basements with 9 ft. of backfill.
I always specify the bolts closer - sometimes 16" O.C. at basements in order to properly react the backfill forces.
I have a question, and this is a pet peeve of mine - why do people call them "Roof Rafters"? Aren't they just "rafters". Is there another type of rafter?
RE: SST Twist Strap at Every Roof Rafter?
You have to trace your loads all the way down, regardless of "aggregate" capacity.
RE: SST Twist Strap at Every Roof Rafter?
RE: SST Twist Strap at Every Roof Rafter?
RE: SST Twist Strap at Every Roof Rafter?
You all might consider looking at the IBHS website at http://disastersafety.org for a bit more than minimum on load path connections. They have done quite a bit of research on the topic, and the free, downloadable FORTIFIED guides provide details which make buildings survive windstorms much better than minimum code.
RE: SST Twist Strap at Every Roof Rafter?
Will sheathing span 48"? Nail withdrawal between sheathing and "anchored" rafter? Can the anchored rafter support three times the uplift? I guess in theory, if you can get all these things to work, it would be OK to skip one or two straps. I doubt you'll get the entire load path to work without some odd detailing call-outs (e.g., and unusual number of nails at the anchored rafters); it just seems like poor detailing in any case.
RE: SST Twist Strap at Every Roof Rafter?
RE: SST Twist Strap at Every Roof Rafter?
My comment was more tongue and cheek about the fascia and sheathing. However, there is some redundancy there (I actually meant the sub-fascia)
RE: SST Twist Strap at Every Roof Rafter?
RE: SST Twist Strap at Every Roof Rafter?
In Russia building design you!
RE: SST Twist Strap at Every Roof Rafter?
Rafters are identified for the roofs, because they are (typically) installed on a
diagonal plane, whereas walls use "studs" installed in the vertical plane, and ceilings use "joists" installed in the horizontal plane.
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RE: SST Twist Strap at Every Roof Rafter?
globetrekker, I think you missed his point. His pet peeve is with the redundant word roof. In other words, you can't have a "floor" rafter. A rafter, by definition, is a roof member.
RE: SST Twist Strap at Every Roof Rafter?
Yes, there is other kinds... there is steel rafters, there is wood rafters, then there is those thar rafters what drift down them thar rivers. Sometimes called white water rafters, but not to be confused with them thar white wood rafters, at the bog box store. Then there are floor rafters when you intentionally want the floor to slope kinda like an almost flat ruuf. You certainly couldn’t call these floor joistes, since they slope. And, then you sometimes see carpenters who don’t understand how to use a tape measure or level installing window headers, which could as well be called window rafters given their slope. I think you should name your pet something other than ‘peeve.’ I’ll buy you a beer the next time we meet, to take your mind off your pet, Peeve.
RE: SST Twist Strap at Every Roof Rafter?
In Russia building design you!