Calculate Rain Gutter Size

Box gutter with rain water head at end of box gutter.

Calculate rain gutter size. Measure the height of. Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. 6 inch 7 960 square feet. The steeper a roof s pitch the more windblown rain it can collect.

To limit the effects of thermal expansion in gutters 50 ft. How do you calculate gutter size. Measure the roof to get the watershed area the area from which water will run off. Multiply length peak to.

In response smacna s technical resources department has created a free downspout and gutter sizing calculator. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website. Find the rainfall intensity for your locale. Calculate the area of a roof to work out how much guttering is required so for a roof that is 5 m long with a height of 4 m and the roof width is 8 m which makes the half roof width 4m we can calculate the effective roof area like this.

15 m is a practical maximum gutter length to be served by a downspout. If a roof s various drainage areas call for different size gutters go for the biggest one k style. Adjusting for pitch and rainfall. Place a sturdy 20 ft 6 1 m ladder on 1 side of your house so that you can reach.

Simplified suitable for flattish roofs with little or no vertical faces or steep roofs draining to one side of box gutter only or any roof if you are in a hurry and make the necessary allowances for all catchments. See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches. 5m x 4m x 4 2 40 square metres. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.

Rainfall intensity is measured in a 5 minute interval translated. Now architects engineers designers and contractors can easily and accurately size downspouts and gutters according to the specifications in smacna s architectural sheet metal manual 7th edition 2012. Measure your gutter across the top from the back where the gutter meets the home to the outer edge. Measuring existing gutters 1.

Then use the chart below to see what size gutter you need. Find the width of the gutters. 5 inch standard k style gutter shop 5 gutterbrush. Run the tape measure from 1 corner of the gutter as far as you can go toward.

The saf perimeter systems gutter downspout capacity table click to enlarge relates downspout size to gutter sizes. Downspout sizes must not exceed the bottom width of the gutter. 5 inch 5 520 square feet. Measure the length of each gutter run.