Reverse? birdsmouth condition

[MyCupboard]

My question is, if i keep the rafter notch to less than 1/4 the rafter depth, can i apply the birdsmouth as illustrated in my screen shot rather than lifting the rafter so that it intersects with the corner of the beam. i assume i will need to check to make sure the shear stil works for the rafter reaction at the beam.

I have a condition where a rafter is creating a sort-of reverse birdsmouth condition. Not the standard birdsmouth shown in figure R802.7.1.1 of the 2018 IRC. but imagine you have that same condition and you shift the entire rafter down (vertically), so that the notch is still less than 1/4 rafter depth but the bottom of the rafter hits closer to the middle of the wall (or beam in my case), rather than intersecting at the top, interior corner of the wall (or beam in my case).

i'm attempting to attach a screen shot showing my rafter in blue with the 1/4 rafter depth measurement in dashed grey. and the beam is obvious.

 

[XR250]

As long as it was 1/4 depth max, I'd be ok with it.

 

[MyCupboard]

as i'm looking at my screen shot more, i'm noticing the line of my rafter notch is actually taken at the top right corner of the beam, not the top left....so really, my rafter notch is greater than 1/4 rafter depth. If this still works for the shear at the reaction, am I good or do i need to take other conditions into consideration (like splitting or something).

 

[MyCupboard]

As long as it was 1/4 depth max, I'd be ok with it.

i'm still learning how to use this site, but i'm attempting to reply to XR250 directly, haha!

thank you for the feedback. i'll keep this in mind and now realize that my notch exceeds the 1/4, per my most recent comment

 

[271828]

This detail causes high tension perpendicular to grain at the notch. Before I do that, I'd continue the horizontal cut farther to the left until it hits the bottom of the rafter, although I'm not wild about that either.

 

[MyCupboard]

This detail causes high tension perpendicular to grain at the notch.

yes i was worried someone would say this. do you know of any references i can look at to learn more about this in order to analyze the condition accurately? i don't recall if NDS talks about the tension perpendicular to grain like this condition.

 

[jayrod12]

To me, this is a standard notch. As long as at the end of the required bearing length (which likely isn't the whole width of the wall) the notch is less than d/4, and the remaining section is sufficient for the shear, then I don't see the issue.

 

[jerseyshore]

You see this a ton in older homes and it gets very dicey in beams and floor joists long term because of the loads and cut sizes. I hate these types of cuts because of the shape and high tension as 271828 mentioned above. With a circle saw they always overcut the notch and it reduces the section even further. I'd prefer a taper and checking the smaller end section for shear.