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Small Cabin Forum / Cabin Construction / Rafter Design - Notching vs Blocking
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ArkansasCabin
Member
# Posted: 4 Nov 2012 23:17
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I'm in the process of designing my rafters, and I'm at a standstill. Is it neccessary for me to notch the rafters? or can i go about building them without notching them, and putting "blocks" inbetween each rafter and nail it to them? I'm trying to attach a picture so you can have a better understanding of what I'm asking.

To better explain, I'd like to have my gable style rafters sit directly atop the framed walls, and in between each rafter, nail blocking so i can attach the rafters from each side, opposed to having to notch them out.

thanks for your help in advance!
rafter design
rafter design


ArkansasCabin
Member
# Posted: 4 Nov 2012 23:23
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Another picture to explain what im talking about.
forum_2.jpg
forum_2.jpg


grover
Member
# Posted: 6 Nov 2012 21:46
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Are these rafters or trusses? I think rafters need to be noched as in "birdsmouth" but trusses should not be notched at all.
Do I understand you question?

MtnDon
Member
# Posted: 6 Nov 2012 23:03
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Those seem to have elements of a truss design about them, without actually being trusses.

Rafters have the birdsmouth notch to supply a flat surface to sit on another flat surface. Rafters strike more fear into the hearts and minds of the DIY it seems to me, but they are not all that difficult to make. The first pair is the hardest. Once they are made they can be used as a pattern to cut the rest. This does depend on the walls being plumb, square and level as only then will all the rafters be the same.

To make something as illustrated all the joints should be covered with plywood plates on both sides. this used to be done back in the pre - 1950's. You may still find plan books at some of the Ag Colleges and Universities in the midwest. I have one someplace. They can be used to make large trusses. Many barns and ag buildings are still in use that have these. They do not meet modern day codes though. And IMO, short spans are so easily spanned with standard rafters that building trusses like these is too time consuming for too little return.

GomerPile
Member
# Posted: 7 Nov 2012 10:31
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Whats the pitch of that roof? It does not look to be very much. You may not be able to use shingles.

I'm also guessing that you're "trusses" are made from 2x4's. In that configuration I don't think they will have much load bearing capacity and may sag under the weight of a roof.. If the span is small enough they you may get away with it.

Replacing the members in the middle with solid triangles of OSB would provide more strength and probably be cheaper. Sort of like an I-beam:

OSB

larry
Member
# Posted: 7 Nov 2012 21:39
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rafters are simple and easy to figure out. buy a framing square and learn how to make rafters..youtube!
IMAG0140.jpg
IMAG0140.jpg


Borrego
Member
# Posted: 7 Nov 2012 22:05
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You need to notch the rafters (birdsmouths) and block between the rafters where they sit on the top plate.. also block midspan between the rafters..

toyota_mdt_tech
Member
# Posted: 16 Oct 2019 15:47
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Blocks will keep rafters from just flopping over too.

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