The more roof surface above the gutters the more rainwater will be caught and funneled down into those gutters.
Roof area per downspout.
Smacna s new downspout and gutter sizing calculator enables the user to manually enter the design area of the roof or use the design area wizard for the calculation.
Rainfall intensity should always be checked with the local authorities.
Gutters and downspouts are vulnerable for obstructions caused branches and leafs from surrounding trees and similar.
Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.
A large roof is going to move a lot of water which means the downspout locations may need to be adjust to compensate.
A high slope moves water more quickly and if gutters have trouble dealing with a lot of water in a short period of time an extra downspout can alleviate that issue.
Gutters come in many sizes.
Secondary cause of gutters not working properly is improperly maintained or failing.
This wizard makes it easy to calculate the roof design area by providing various shape calculations and the calculation for vertical walls area per international plumbing code ipc.
Large gutters can hold more water.
Up to 6 12 7 12 8 12.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
Roof area square feet per linear ft of gutter underneath.
The table is based on rainfall intensity 100 mm per hour 4 inches per hour.