Calculate How Many Downspouts Gutters Need

Once you add up the square footage of your roof you can then determine the number of downspouts.

Calculate how many downspouts gutters need.

3200 square feet of roof is calculated as 3200 600 5 33 rounding up you would need 6 2x3 downspouts. The code limit is 150mm for dp s and 26 800 sq mm for flat eaves gutters the program will calculate the size and number of downpipes downspouts leaders required and the eaves gutter sizes for any roof. The catchment area of a roof and any vertical walls is greatly influenced by the direction of wind driven rain therefore the combined catchment area must be used for sizing purposes. Downspout sizes must not exceed the bottom width of the gutter.

2 by 3 inches 600 square feet. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area. 3 by 4 inches 1 200 square feet. Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of drainage area.

If we have to sum it up in a single rule gutters need a downspout around every 30 to 40 feet. Measure the roof to get the watershed area the area from which water will run off. For most homes this means installing spouts at either end of a gutter section. Find the rainfall intensity for your locale.

It is used in 95 of all installations and works for all sloped roofing materials shingles metal slate wood etc. 6 k gutter is used for higher volume of water runoff to a single point typically on flat roofs or larger commercial buildings. Enter larger gutter widths in the yellow boxes to find out how wide your gutters need to be given the length that you want to go between downspouts. Refer to as nzs 3500 3.

Minimum top opening width max. How to calculate gutter and downspout capacity step 1. There is no limit to downpipe size or eaves gutter size. For hipped roofs with eaves gutters a simplified formula can be used to calculate catchment area but the slope of the roof must be known.

Use the chart below to figure out how many extra downspouts you need. To limit the effects of thermal expansion in gutters 50 ft. Use the chart below to figure out how many extra downspouts you need. As with gutters a downspout s capacity must match or exceed the expected runoff.

There are many more important factors that can change this broad rule. Multiply length peak to. 6 gutters typically use 3 4 downspouts to accommodate higher volume of water. Rectangular 2 by 3 inches 600 square feet 3 by 4 inches 1 200 square feet.

How many downspout installations should your gutters have. Remember two gutter lengths can share the same downspout so if you calculate the max gutter to be 40 feet you could put a downspout halfway in an 80 foot length. 15 m is a practical maximum gutter length to be served by a downspout. Rainfall intensity is measured in a 5 minute interval translated.

5 gutters typically use 2 3 downspouts. Hello bb10 and welcome to the community.