Fill in the areas in RED to calculate membrane area of ice / water / membrane for eaves. If valley
SQFT is required, fill in areas in BLUE. Results for each & accumulative total appear in GREEN

Rise (y):
1.75

"The IWS Calculation Triangle"

Rafter (h):
3.91
Run (x): 3.5

Run is calculated by Pythagorean Theorem area of 2 ft. to the interior, considering a 6" exterior to interior wall, in correlation of pitch.

Degrees:
26.57
Pitch:
6/12
Roof Pitch
/12
Overhang (inches)
Eave Length LF
Additional Inches
Valley
LF

Additional
Inches

Overhang Example
SQFT of Eave Areas Only
963
Total Valley SF
178.8
Total SQFT
(Eaves + Valley)

1141.7

Variables

Roof Pitch: /12

Rise:

Run, calculated:

Rafter:

Calculates area of 2 ft. to the interior, inculding a 6" exterior to interior wall

Run = Eave overhang + 6" exterior wall to the interior of home
Eave Length:
** Note: Keep in mind variations in pitch and overhang would be calculated separately if not consistent throughout the roof eaves.