## Sunday, September 13, 2015

### Off Angle California Valley Framing

Off Angle California Valley Rafters can be calculated using one of my RafterTools+ apps.

On this house the main roof slope is an 4:12 pitch and the off angle California framing is at an 6:12 pitch. First enter 4:12 for both the Main and Adjacent Roof Pitches, with an Eave Angle of 90°. The calculated results will give you the Main Roof Hip Rafter Slope Angle = 13.26268° and the  Main Roof Hip Rafter Back Angle = 12.92097°.

To calculate the California Jack Rafter Foot Miter Angle and Saw Blade Bevel  Angle for the Off Angle California Valley Framing  can be accomplished by entering an Eave Angle of 45°, Main Roof Slope Angle = 18.43495° (4:12) and Adjacent Roof Slope Angle = 26.56505° (6:12)

Roof Eave Angle = 45°
Main Roof Slope Angle = 18.43495° (4:12)
California Valley Roof Slope Angle = 26.56505° (6:12)

Main Roof Hip Rafter Slope Angle = 13.26268°
Main Roof Hip Rafter Back Angle = 12.92097°

With the RafterTools+  calculated results you get an

Valley Sleeper Saw Blade Bevel Angle = 48.46304°

For the Jack Rafter Foot  Miter Angle you add the California Valley Roof Slope + Main Roof Hip Rafter Slope Angle.

Jack Rafter Foot  Miter Angle = California Valley Roof Slope + Main Roof Hip Rafter Slope Angle
Jack Rafter Foot Miter Angle = 26.56505 + 13.26268 = 39.82775°

For the Saw Blade Bevel Angle used on the Jack Rafter Foot Cut

Saw Blade Bevel Angle at Jack Rafter Foot Miter Cut = Main Roof Hip Rafter Backing Angle
Saw Blade Bevel Angle at Jack Rafter Foot Miter Cut = 12.92097°

The  RafterTools+ has the California Jack Rafter Length Difference  or use the following Trigonometry formulas.

Roof Sheathing Angle = arctan(sin(Jack Rafter Foot  Miter Angle) ÷ tan(Main Roof Hip Rafter Back Angle)
Roof Sheathing Angle = arctan(sin(39.82775) ÷ tan(12.92097) = 70.29288°

California Jack Rafter Length Difference = O.C. Spacing ÷ tan(Roof Sheathing Angle)
California Jack Rafter Length Difference = 24” ÷ tan(70.29288) = 8 5/8"

The Valley Sleeper Miter Angle is not built into the RafterTools+ apps. You can use the following formula for the miter angle at the foot of the Valley Sleeper.

Valley Sleeper Miter Angle = arccos( cos(Sheathing Angle Angle) × cos(Jack Rafter Miter Angle at Foot))
Valley Sleeper Miter Angle = arccos( cos(70.29286°) × cos(39.82772°)) = 74.99102°

With a Valley Sleeper Saw Blade Bevel Angle of 48.46304°, you can use this formula for the snap line dimension on the Valley Sleeper for the edge bevel.

Edge bevel width = Valley Sleeper Thickness / tan(Valley Sleeper Saw Blade Bevel Angle)
1.69323 = 1.5 x tan(48.46304°)
or 1 11/16" = 1.5 x tan(48.46304°)

Set the saw bevel angle to 48.46304° for the Valley Sleeper edge bevel.

After you have edge beveled the valley sleeper you can use the Valley Sleeper Miter Angle (74.99102°) for the Valley Sleeper foot cut.

This porch has trusses and I aligned the valley sleeper with the edge of the truss for the location of the valley sleeper.

The ridge cut has a 4:17 miter angle to set on top of the main roof valley rafter. I scribed the miter angle for the valley sleepers at the peak.

For the Off Angle California Valley Jack Rafters I laid out the 6:12 level cut, then used the 39.82 angle for the Jack Rafter Foot Miter Angle.

For the Off Angle California Valley Jack Rafters length difference I used the 8 5/8"  from the RafterTools+app.

The extra blocks at the ridge are for a CS14 strap that runs the full length of the roof. The second row of blocks are for plywood sheathing edge nailing.