Minimum Roof Area Before I Need Roof Drainage

Evidently there are set standards for the different kinds of roof slopes.

Minimum roof area before i need roof drainage.

There are 5 easy steps to figure out how many drains your commercial roofing project will need. An additional roof drain should be added for each 10 000 square foot area. Calculate total roof area. Calculate the total roof area by multiplying its length by width.

Roof replacement or roof recover of existing low slope roof coverings shall not be required to meet the minimum design slope requirement of one quarter unit vertical in 12 units horizontal 2 percent slope in section 1507 for roofs that provide positive roof drainage. The drainage system of any roof can be located at the edge or in the middle of the roof. It is a requirement of building regulation part h that adequate provision is made for rainwater to be carried from the roof of the building. Assume you are tasked to size a horizontal roof drain serving 5 000 square feet of roof area on a building located in dallas tx.

For a large roof it is recommended to have drains placed at multiple locations within the area of the roof. Roof drainage systems need to be designed to cope with the rainfall intensities for the specific building location. Increasing the angle of a flat roof will always increase the speed of water movement across the surface. Determining the exact roof area and the number of drains is precise work so it requires coordination with the building s architect.

Determine leader or pipe size. A good rule to follow is to provide two roof drains for a total roof area less than 10 000 square feet. Once the drainage system is determined the designer must ensure positive drainage by correctly positioning the roof drains. Adding a roof can create drainage problems if the roof pitch is too shallow.

Minimum roof pitch the minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. Walls that drain onto a lower storey roof can increase the effective roof area by around 50. It s easier to see how this works with a real world example. Drainage design specific to location.