A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
How many feet are my gutters.
If you live in a warm place with sporadic rain you can hang gutter hangers close to the middle of the gutter with a spacing of no more than 36 inches or three feet apart from the center.
Therefore this roof should be equipped with 6 inch k style gutters.
If the adjusted square footage is equal to or less than 2 500 feet 760 m choose 5 in 13 cm half round gutters.
Step 1 position a ladder at one end of a wall with a gutter or where one is to be installed.
For square footage up to 3 840 feet 1 170 m use 6 in 15 cm half round gutters.
The 6 in 12 pitch factor 1 1 multiplied by 1 000 yields an effective area of 1 100 square feet.
The bigger your roof and the more rain you get the bigger your gutters will need to be.
For downspouts a good rule of thumb is one for every 40 feet of guttering.
Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.
Multiplying that number by the local maximum rainfall intensity 6 8 inches per hour yields an adjusted square footage of 7 480 square feet.
The above recommendations assume that you have properly sized downspouts every 40 feet.
Doubling the number of downspouts halves the required capacity for each.
Always inspect ladders before using them and make certain the feet of the ladder are secure before climbing up.
Gutters come in k style and half round style.
For rainy climates where gutters will handle a larger amount of water for long periods they should have a maximum distance of 18 inches apart between them.
Size downspouts to fit the gutter.
Next you ll need to choose your material.
As with gutters a downspout s capacity must match or exceed the expected runoff.
Adding a 2 by 3 rectangular downspout for instance boosts your gutter s capacity by 600 square feet of.