SHEATHING BEVEL ANGLE AT VALLEY LINE

SHEATHING BEVEL ANGLES AT VALLEY LINE (For butt joints)

Sheathing is often not beveled to make a butt joint at the valley line, since it may be considered a needless refinement. However, beveling makes for a neater and tighter joint. To make the bevel, cut on the back side and angle the skill saw table the amount shown in this table. Angle values in degrees.




Use the following formulas to calculate these angles for other roof combinations:

Bevel Angle for steep roof = ArcSin {{[S/(Cos Sangle(S^2 + 144)^0.5)] – [S/((S12/F)^2 + 144 + S^2)^0.5]}/Tan Sangle}Bevel Angle for flatter roof = ArcSin {{[F/(Cos Fangle(F^2 + 144)^0.5)] – [F/((F12/S)^2 +144+ F^2)^0.5]}/Tan Fangle}

Example: A 3:12 pitch roof intersects a 5:15 pitch roof. What is the bevel angle for the valley sheathing for the steepest roof?

Bevel Angle = ArcSin {{[5/(Cos 57.0^0(5^2 + 144)^0.5)] – [5/((5x12/3)^2 + 144 + 5^2)^0.5]}/Tan 57.0^0} = ArcSin {(0.706 – 0.21) /1.54} = 19 degrees


Thanks to Boiseans David Valentine and Bob Firman (famous Idaho Math Maven) for help with these equations.