Gutters come in different sizes.
How to size gutters.
This determines the maximum watershed level gutters can serve between downspouts.
You ll also need to.
Calculate your roof.
You have three options.
Consider your drainage area.
See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches.
Area and flow in table 1 4 are based on 1 in 25 mm of rainfall per hour.
How do you calculate gutter size.
Gutters come in different sizes.
Get 7 or 8 inch gutters.
Find the width of the gutters.
Ft and a 3 in.
Downspouts also come in.
The standard is about inch per 10 feet.
Make sure the ladder extends at least three feet.
Increase the pitch of the gutter.
Size downspouts to fit the gutter.
5 inch standard k style gutter shop 5 gutterbrush.
Each square inch of downspout cross section can drain 100 sq.
Adjusting for pitch and rainfall.
Divide these areas by the local rain fall rate in inches per hour to determine the actual roof area to be served by the gutter diameter.
Measure the length and.
How do you do the math to figure out how large your gutters should be.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
Gutters typically come in 5 or 6 in 13 or 15 cm sizes and can be k style or half round place a sturdy 20 ft 6 1 m ladder on 1 side of your house so that you can reach the gutters.
Carefully climb up the ladder and measure the width of the opening at the top of the gutters.
Spout drains up to 600 sq.
From chart 1 2 it is determined that a 9 5 in 241 mm half round gutter should be used.
How to size gutters downspouts 1.
Doubling the number of downspouts halves the required capacity for each.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted.
Place the torpedo level on the roof with the level body sitting perpendicular to the roof peak.
Increasing the pitch increases a gutter s.
Spout drains 1 200 sq.
Pitch your gutters by 1 8 in.
Per ft and you can multiply the watershed by 1 4.
What size gutters do you need.
They ll cost more and probably require a custom order through a professional installer.
Set up an extension ladder against one edge of your home s roof.
Measure your gutter across the top from the back where the gutter meets the home to the outer edge.
