Hi everyone. I was wondering if using the diamond shaped steel ties for garage rafters, would you still need a bird’s mouth cut? This would be 2 by 6 or 2 by 8 rafters, not trusses. It seems that with all the retention in a steel tie the bird’s mouth cut would be redundant. Or is it the code? Thank you.
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Rather than rely on a mechanical connection for bearing, I think it would be easier to go ahead and cut the birdsmouth. It's probably easier than posting the question here, and would take less time.
If you don't you are a relying on the nails for bearing, and although I think I know the connector you are referring to, I don't think it would be the strongest method.
If you can cut the plumb cut at the top of the rafter, you can handle the birdsmouth.
Enlighten me as to why you don't want to cut the birdsmouth. Building codes are silent on alot of issues (ie. deck ledger attachement) and I'm not sure you'll find help there, but it may be irrelevant.
Tom
J-
By "diamond" clip, I think you're talking about what Simpson calls a H1 hurricane tie. I've attached a picture, and you can go to http://www.strongtie.com for more info.
Their literature says that the H1 can be used to "eliminate costly rafter notching" if installed on the outside face of a wall. They note that if installed on the inside face of a wall, you will need to cut a birdsmouth on the rafter.
I'm not a big fan of strong ties, because they just seem to get in the way of sheathing, finish trim, etc. However, it seems you can do what you're asking about.
Ragnar
I assume you're talking about the Simpson "H1", or a similar tie like Ragnar posted a picture of.
The allowable force for the Simpson "H1" (Perpendicular to the plate) is only 165 pounds. That's probably enough for a building about 6' wide.
They're mainly meant for holding a rafter or truss DOWN, not resisting compression loads.
So I would say it's a bad idea. Go with the birdsmouth.
Be naughty - Save Santa the trip
I agree with Boss. H1s are primarilly to resit uplift. If you taper your top plate I think it's fine to not birdsmouth your rafters, but that's a lot of work too. All that being said, it depends on what I use for rafters. I don't like notching the flange on I-joists, so that would be a case where I'd consider a tapered plate or maybe a saddle type connector.
As far as relying on mechanical fasteners, I think most of the framing hardware we install with teco nails is far superior to the toenailed connections we used to use around here before the seizmic codes got so stringent. They are a pain in the butt, but I think for the most part they are better.
Any code related question is best answered by a structural engineer or local building official. Local soil and tectonic plate configurations, along with climate, dictate most local variations from each other.