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Glulam ridge beam rafter overlay or notch

lpranger467's picture

 Sorry about the 1st grade drawing. But with a glulam ridge beam would it be best to notch the rafters (right side drawing) or not notch the rafters (left side) and overlay the beam then put a plate (mini collar tie) across ?


The rafters will be 2 x 10s and bottom will be covered in drywall. Lower portion of glulam will be exposed. 

Thanks very much

Do not notch the rafters. (post #215194, reply #1 of 4)

Notching the rafters as you show weakens them in shear at exactly the point where shear load is greatest. Without suport here for the bottom of the rafter you invite falilure in horizontal shear as well. You could set them on top and use a ridge board that rests on the beam for maximum bearing or you could hang them on hangers. Common method of strapping is across the ridge. 

Thank you (post #215194, reply #2 of 4)

That was my though that the notching would cause a weak point but the framers keep mentioning it saying it will "lock" the beam in place. The glulam beam will be appearance grade so I cant use hangers which is why I was going to put gussett plates between the two.

Ridge board. (post #215194, reply #3 of 4)

You either need a ridge board or solid blocking between the rafters at the beam. Don't worry the beam will be plenty stable without the notches. If you use a ridge board just strap the tops of the rafters. A-35s on top of the beam would be a good idea. 

Sistered rafter (post #215194, reply #4 of 4)

I dont think it changes anything but I'm actually opening up a flat ceiling so these 2 x 10's will be sistered next to existing 2 x 6's. The existing 2 x 6 does have a ridge board but no beam.