How to calculate gutter and downspout capacity.
How to measure rain gutter size.
Find the width of the gutters.
How to measure downspouts.
Find the rainfall intensity for your locale.
Rain gutters can vary in size.
Measure the diameter of the gutter.
Roof slope rainwater must not overrun the front edge of the gutter.
Multiply length peak to eave by width to determine.
Downspout sizes must not exceed the bottom width of the gutter.
Carefully climb up the ladder and measure the width of the opening at the top of the gutters.
Rainfall intensity is measured in a 5 minute.
Measure length of twine mark the measurement with a piece of tape and then pull the twine off of the other end of the gutter.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
Use your tape measure to determine the length of the twine marking down this calculation.
See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches.
Adjusting for pitch and rainfall.
How do you calculate gutter size.
Then use the chart below to see what size gutter you need.
Furthermore the standard norm for gutters among many in the rain carrying industry is to allow 1 square inch of outlet opening in the gutter for every 100 square feet of roof area being drained.
The steeper a roof s pitch the more windblown rain it can collect.
Measure your gutter across the top from the back where the gutter meets the home to the outer edge.
If a roof s various drainage areas call for different size gutters go for the biggest one k style.
A steep pitched.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted.
5 inch 5 520 square feet.
6 inch 7 960 square feet.
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.
Measure the roof to get the watershed area the area from which water will run off.
If a new home is purchased but the sizing isn t known take a ladder and climb up with a measuring tape.
