Installation Instructions

5
estimating for soffit
Soffit material will be used on the front and rear eaves, the gable
overhangs, the dormer overhangs and any porch ceilings.
Calculating the Eaves
For the front and rear eaves, add the total length of each section and multiply by the width. The width is a straight-
line distance from the wall to the tails of the rafters. This would also be done on the ends of the home on a hip roof.
Our sample home in GENERAL ESTIMATING TIPS was 40' long with a 12" overhang on each of its two gables.
Total length of the home then, would be 42'. If the overhang is 12" on both the front and the rear eave, then the
square footage of soffit needed is 42' x 1' = 42 sq. ft.
The back is a duplicate of the front so the total is 42 sq. ft. + 42 sq. ft. = 84 sq. ft.
These low eaves will require vented soffit for attic ventilation, so we will order 1 square of vented soffit for this job.
Use the same process of rounding up to the next highest 3" increment as described in GENERAL ESTIMATING
TIPS. Do the same for any dormer eaves.
Calculating the Gable Overhangs
For the gable or dormer overhangs (rakes), you must determine the length of each section. These will be angled and
the length will be dependent upon the pitch of the roof. The easiest way is to scale them off of the building plan.
If you don’t have access to the plan, here is the process.
Let’s use the same home we used in GENERAL ESTIMATING TIPS. The width of this home was 30' with a 12"
overhang, front and rear, making the gable width 32'. The run is half this width or 16'. The height as we calculated
earlier was 6.72'. To figure the diagonal, which is the measurement we want, we do the following:
Multiply 16' x 16' and record the answer. (16' x 16' = 256')
Multiply 6.72' x 6.72' and record the answer. (6.72' x 6.72' = 45.16')
Add the two answers. (256' + 45.16' = 301.16')
Put this number into your calculator and hit the square root button.
The answer is 17.35'.
This is the length of one side of the gable or soffit overhang.
As there are always two pitched sides to a gable or dormer, multiply the result by 2.
17.35' x 2 = 34.7 linear feet. Round it up to 35 linear feet.
Multiply this by the width of the overhang. Let’s assume 12" or 1 ft.
35 linear feet x 1 foot = 35 square feet. Enter this into your worksheet.
The other gable is the same, so enter 35 square feet for it into the worksheet.
Total soffit material required for both gables is 35 + 35 = 70 sq. ft. This does not have to be vented,
so solid soffit is ordered for this section. We will order 1 square of solid (non-vented) soffit for this portion.
Continue this same process for all gables and pitched dormers.