I need to decide how to join the gambrel roof rafters on the barn I'm
building to the top plates running along the top of the side walls.
The top plates are 8" by 8" beams. The rafters are 2" by 8". (These are
all actual sizes, native lumber). The angle they meet at is 55 degrees.
I'd like to do more than the small 'birds mouth' that occurs the way the
pieces meet, by some amount of cut-in to the plates. But what's the best
compromise of attaching strength VS minimizing the material removed from
the plates? What's a strong geometry here? I can rout some shaped cut-in
in the plates, but I'd sure like to do that on the ground, soon now.
I will have 1" thick purlins on the outer surface, and so I can set the
rafters in 1" more than shown to get more material at the inner end of
The max. bad wet snow load is 1500 pounds vertical, and 1000 pounds
outward. I plan to use a 1" wooden peg or a large lag screw in each
joint; this is not necessarily traditional timber frame construction
Take a look at:
for what this looks like.
Suggestions, pointers, comments appreciated! I have some books but I
haven't found this joint discussed.
Regards, Terry King ...In The Woods In Vermont
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