Attaching porch overhang rafters to house rafters with 150lb snow load? Doable?

[black_edelweiss]

Im building a porch overhang similar to whats pictured, and was wondering what the best way to connect the porch rafters to the current house roof would be. We have a 150lb snow load and the snow will definitely be piling up several feet above the overhang as it slides off, and will be accumulating several feet on the overhang structure. My current porch rafters are 2x8 which span 16ft spaced every 16inches, and attach to a 2x8 plate which is nailed onto the house rafters which are 2x6 with 16" spacing and span roughly 12ft. The slope of the house roof is 11/12.

I'm primarily curious what the best way to attach the porch rafters to the 2x8 plate would be. Is there a simpson tie that anyone recommends for this? Any advice or tips are greatly appreciated. Thanks

[DaveOrr]

What I did was to notch the porch rafters and sit them on the top plate of the wall beside the roof rafters.
I then tied them to the roof rafters for strength and to keep them from twisting.
The cabin roof is 6:12 pitch and the porch is 3:12.

[ChugiakTinkerer]

Is the house roof already sheathed?  If not, I would bevel the 2x8 plate so that the porch rafters rest flush on the plate and overhang enough to attach to the roof rafters.

If house is already sheathed I would still bevel the 2x8 plate but secure it with structural screws rather than nails.  You want to prevent uplift and nailing might not be sufficient.  Attach the Simpson tie to the plate with structural screws too.  Again, you want to hold against uplift.  You can nail the tie to the porch rafter.  Put blocking between the porch rafters at the top and bottom to prevent racking.

The change in slope will likely collect quite a bit of snow.  The porch beam will carry half the load, but the other half of the porch snow load will be bearing on the rafters at the connection point.  I would do some concentrated load calculations to better understand how much snow accumulation your roof rafters can withstand.

[Don_P]

consider a kneewall above the existing exterior wall up to the underside of the porch rafters to lighten the load on the existing rafters and to shorten the span of the porch rafters. 150 psf is engineer territory.