# gable height



## lemoncoke (Nov 19, 2006)

what is the formula for a gable end. How do you figure out the height of a gable with a 4/12 pitch and abuilding of 24' long and 8' high walls is there a formula for figuring this out without measuring it. Thanks Rick


----------



## Kgmz (Feb 9, 2007)

4/12 is 4" high per 12" of run.

So for a 24' wide building you take half 12' x 4" = 48" so the top point of the truss or rafter is 4 ft taller than the wall it sits on.

Figure the 8' wall which is actually 8'-1 1/8" tall if it is using 92 5/8" studs with 1 bottom plate and 2 top plates. Add the 4' tall truss plus any plywood on the roof and roofing. Then add the floor height which is depth of joists + floor sheathing + sill plate on top of foundation. Then add whatever foundation is above the ground level. Add them all up and you will have the total height of building.

So rough guess add 50" for roof, 8'-1 1/8" for wall, assume 2x10 or equivilant I joist of 9.5". 3/4" plywood decking, a 1.5" sill plate, and 8" of foundation above ground. = 13'-10 7/8" tall.


But for a building that short I could hook my tape on the ridge and measure down.


----------



## Ed the Roofer (Dec 12, 2006)

The formula is a neat way to be precisely accurate, but if I have to calculate the rafter spans, I cheat and look at the table for various pitches found in the ARMA, (Asphalt Roofing Manufacturers Association), manual, which can be ordered from their online store.

You could also use the Pythagorean theorum to finish off your calculations if you know any 2 of the 3 measurements.

Ed


----------



## wasdifferent (Dec 18, 2004)

Kgmz said:


> ...the top point of the truss or rafter is 4 ft taller than the wall it sits on...


Plus the width of the rafter or truss (measured vertically) from the corner of the bird's mouth to the top edge.


----------

