Pitch your gutters by 1 8 in.
How to size gutters.
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.
Downspouts also come in.
From chart 1 2 it is determined that a 9 5 in 241 mm half round gutter should be used.
See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted.
The steeper a roof s pitch the more windblown rain it can collect.
Spout drains 1 200 sq.
What size gutters do you need.
Measure the length and.
Measure your gutter across the top from the back where the gutter meets the home to the outer edge.
Find the width of the gutters.
5 inch standard k style gutter shop 5 gutterbrush.
Gutters come in different sizes.
Get 7 or 8 inch gutters.
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.
Gutters come in different sizes.
Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed.
You ll also need to.
Ft and a 3 in.
Make sure the ladder extends at least three feet.
Spout drains up to 600 sq.
Calculate your roof.
Size downspouts to fit the gutter.
How do you do the math to figure out how large your gutters should be.
Increasing the pitch increases a gutter s.
You have three options.
How do you calculate gutter size.
Consider your drainage area.
Adjusting for pitch and rainfall.
A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour.
Per ft and you can multiply the watershed by 1 4.
Area and flow in table 1 4 are based on 1 in 25 mm of rainfall per hour.
Place the torpedo level on the roof with the level body sitting perpendicular to the roof peak.
How to size gutters downspouts 1.
They can be 4 5 or 6 inches.
Each square inch of downspout cross section can drain 100 sq.
Doubling the number of downspouts halves the required capacity for each.
The standard is about inch per 10 feet.
Carefully climb up the ladder and measure the width of the opening at the top of the gutters.
