DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   Building & Construction (http://www.diychatroom.com/f19/)
-   -   notching rafters depth help please (http://www.diychatroom.com/f19/notching-rafters-depth-help-please-155654/)

driftwoodtackle 09-03-2012 09:44 AM

notching rafters depth help please
 
Im using 2x12 rafters.12 12 pitch cathederal ceilings. My plans tell me i can only birdsmouth cut 1/6 of my rafter. Does this sound right? I guess for strength of board? Only gives me a 2" notch.

tony.g 09-03-2012 11:17 AM

Being at the end of the rafter, the bending stress is almost zero so you can notch it deeper than that, particularly for a 12" rafter.
The important point is to get a good full bearing on the wall plate.

hammerlane 09-03-2012 11:21 AM

2 Attachment(s)
See if this helps

Hammer450R 09-03-2012 11:28 AM

12 pitch i would go full bearing 3 1/2" or 5 1/2" seat cut depending on exterior wall size

driftwoodtackle 09-03-2012 11:41 AM

Our plans only allow 1/6 nominal depth. If i use 2x12 that is only 2 inches.

Hammer450R 09-03-2012 11:47 AM

Call your arch, I'm sure he would rather have full bearing than 2 inch...the 1/6 is probably a generic side note.
The deeper the birdsmouth doesn't weaken the rafter until you go past full bearing.
But if there is floor joists next to the rafter then 2 inch is fine. Cut and be done with it.

GBrackins 09-03-2012 01:15 PM

Quote:

Originally Posted by driftwoodtackle (Post 1002218)
Our plans only allow 1/6 nominal depth. If i use 2x12 that is only 2 inches.

a bird's mouth is not a notch, not in the traditional sense of a notch. It is a bearing seat cut. what you have is a cantilever for the overhang that extends past the wall.

check out comments from the "Building Codes Forum"

http://www.inspectpa.com/forum/showt...t=rafter+notch

Gary in WA 09-03-2012 09:15 PM

Beat me to it, Gary! LOL Well, here's the other one; http://publicecodes.cyberregs.com/ic...?bu2=undefined

Gary

GBrackins 09-03-2012 09:24 PM

and the two will make a whole ....


All times are GMT -5. The time now is 10:06 AM.