I am trying to assemble a patio roof with the dimensions 2x7m and am wondering how large notches I can make at the end of the roof beam, the one that will run between the load-bearing beams.
The purpose of the upper notches (1 and 2) is for roof drainage. I need to set up a gutter or equivalent on the inside of the load-bearing beam.
The lower notch (3 and 4) is for hanging the roof beam. I am thinking of screwing and gluing a strip to the load-bearing beam and then notching out the roof beam.
The question is how large notches I can make without affecting the deflection of the beam?
Are there other considerations besides deflection that I might be forgetting?
For the 2 meter span, I have used calculation software that suggests 45x120 c30 would work. However, I probably need to go up to at least 170 to make reasonable notches.
I spontaneously think that the lower notch would need to be at least 45x45 and the upper notch for roof drainage would probably need to be 70x70.
If the notches would increase deflection correspondingly, then I would need a roof beam that is c30 around 235 cm (70+120+45). My hope, however, is that the notches do not impact the beam as much as 100 percent of the notch dimensions.
