Point Loaded Roof Rafters

[DevinTheStudent]

Hello All,
Recently came across a project with some interesting features where a contractor had renovated and build a flat roof on one half of an existing pitched home. (see photo)

Each 2x6 rafter is now subjected to a point load of 720lbs spanning 13'

What kind of solutions would their be to this?

Currently were are thinking sistering 2x4 to the existing 2x6's along with rafter ties in the upper third

see photo for exterior picture, new roof does not connect at ridge.

 

[Harbringer]

Is the 2x6 is failing in bending. Sistering would help (though you need to shore the existing member).
Is it also failing in shear? Sistering will only help if you can add it all the way to the support so that the combined member is subject to the shear.
Does the existing connection work? Seems unlikely.

Is the 750lb point load dead only or dead + live?

Why are you adding a tie in the upper third? I'd think that the issues is thrust to the walls (ties in the upper third are generally used for uplift).

This is a pretty simple wood problem so I'm not sure what you are asking.

 

[kissymoose]

80psf snow load? 720# sounds high

 

[Harbringer]

It looks like some screw-ball shipping container addition. Who knows how it's framed.

 

[XR250]

80psf snow load? 720# sounds high

My suspicion is that they built a dormer on the back so the point load is at each end of the beam supporting the roof break - not 16" O.C.
What the OP has described really makes no sense, honestly.

 

[BAretired]

Assuming the framing is as shown in the OP, bracing across the rafters engages the opposite rafter in bending. To prevent rafters from separating at the top, an extra 2x4 is suggested. This would be more effective than adding a 2x4 sister member at each rafter.

BA