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Author Topic: Birdsmouth seat size  (Read 1299 times)

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Offline canopy

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Birdsmouth seat size
« on: April 01, 2013, 09:23:01 AM »
I like the look of housed joints much more than flush joints. So instead of laying birdsmouth rafters on the beam outer corner I would like to add housings. However, this reduces the seat to just 2" in depth while remaining 6" wide which is the rafter width. Are there any rules on seat sizing and is this seat too small?

Offline Jim_Rogers

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Re: Birdsmouth seat size
« Reply #1 on: April 01, 2013, 10:00:19 AM »
That is a question for your engineer. I don't remember your roof load, that's why I can't say if it's ok or not.

Jim Rogers
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Offline giant splinter

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Re: Birdsmouth seat size
« Reply #2 on: April 01, 2013, 10:47:59 AM »
The basic idea with this type of connection is to achieve full bearing at the horizontal point of contact or the "seat cut" to support the roof loads while maintaining enough of a grip at the "plumb cut" without destroying the possibility that the rafter tail must be able to withstand its share of weight and loading. What you are proposing should work if you stay within the basic design criteria, however it seems like a lot of extra work to consider doing when you take into account that your rafter connection will be difficult at best to see in view of the fact that unless its an exposed joint you will probably have frieze blocking and some kind of exterior siding covering the joint from view.
roll with it

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