this calculator assumes that the input values are provided in the following units: Roof area: square feet Rainfall intensity: inches per hour Downspout size: square inches Pipe depth: meters Pipe size: inches in diameter Drywell size: cubic feet Drainage trench length: feet Drainage trench slope: inches per foot

Downspout Extension and Drainage System Calculator

Rainfall Intensity (inches per hour):

Roof Area (square feet):

Downspout Size (inches):

Pipe Depth (feet):

Pipe Size (inches):

Drywell Size (cubic feet):

Drainage Trench Length (feet):

Drainage Trench Slope (inches per foot):