Rain Water Gutter Size

To limit the effects of thermal expansion in gutters 50 ft 15 3 m is a practical maximum length of gutter to be served by a downspout.

Rain water gutter size.

If a roof s various drainage areas call for different size gutters go for the biggest one k style. Most downspouts are rectangular but they can also be round or square. 6 inch 7 960 square feet. Size downspouts to fit the gutter.

But houses with big steep roofs or those located in climates prone to heavy downpours may need wider gutters and extra downspouts to keep rainwater from overflowing. 5 inch 5 520 square feet. Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. Gutter downspout sizes are 3 to 6 inches.

The gutter and downspout size requirement depends upon the number of sections and length of the gutter sections as well as the number of downspouts. Also the gutter width in relation to height may also be adjusted. Measure your gutter across the top from the back where the gutter meets the home to the outer edge. Adding additional sections of gutter reduces the length of each section and will reduce the gutter size.

However too large a gutter downspout can look unattractive. Five inch k style gutters or 6 inch half rounds the most common residential sizes are able to handle the rainfall on most houses in most parts of the country. See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches. The larger a gutter downspout the more water it can drain quickly.

Then use the chart below to see what size gutter you need. Use this handy guide to make sure your rain collection is up to the task during even the heaviest storm. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. You should have enough gutter downspouts to effectively handle the size of your entire gutter system.