HOW TO DESIGN TERRACE OR ROOF GUTTER SIZE
Designing the size of roof gutters involves considering factors such as the roof area, rainfall intensity, and local building codes. Here's a general guide to help you determine the appropriate size for roof gutters:
1. Calculate Roof Area:
• Measure the length and width of each section of the roof.
• Multiply the length by the width to get the area of each section.
• Add up the areas of all sections to get the total roof area.
2. Determine Rainfall Intensity:
• Check local weather data or use rainfall intensity maps to determine the average rainfall in your area.
• Rainfall intensity is typically measured in inches per hour.
3. Consider Roof Pitch:
• Steeper roofs may require larger gutters to handle the faster flow of water.
4. Use the Rainfall Rate Formula:
• The rainfall rate formula is: Q=CiA where:
• Q is the flow rate (in cubic feet per second or gallons per minute),
• C is the coefficient of runoff (a dimensionless factor based on roof slope, typically ranging from 0.8 to 1.0),
• i is the rainfall intensity (in inches per hour),
• A is the roof area (in square feet).
5. Choose Gutter Size:
• Once you have the calculated flow rate, you can choose a gutter size that can handle that flow.
• Standard gutter sizes are often expressed in terms of inches, such as 5 inches or 6 inches.
6. Check Local Building Codes:
• Be sure to check local building codes and regulations, as they may specify minimum requirements for gutter size based on factors like roof area and rainfall.
7. Consider Downspout Size:
• The downspouts should be sized to handle the volume of water flowing from the gutters. Ensure that the downspout size complements the gutter size.