Calculate Box Gutter Size

Doubling the number of downspouts halves the required capacity for each.

Calculate box gutter size.

Size downspouts to fit the gutter. Downpipe eaves gutter long straight eaves gutters box gutter to rain water head box gutter vertical faces box gutter side o flow box gutter vertical o flow storm water pipe size storm water network overland flow path spitter upstream end custom rain water head. Sizes the depth shown of the box gutter is the depth at the upstream end. If a roof s various drainage areas call for different size gutters go for the biggest one k style.

Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. Then use the chart below to see what size gutter you need. 5 inch standard k style gutter shop 5 gutterbrush.

5 inch 5 520 square feet. Measure your gutter across the top from the back where the gutter meets the home to the outer edge. Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. Must have a constant slope between 1 40 and 1 200.

6 inch 7 960 square feet. Sides must be vertical. Down pipe must be vertical from sump not to the side minimum sump length is 400mm. See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches.

Learn more how to storm water design for building sites.