Roof Drains


There are a number of different varieties of roof drains and roof drain downspout in Mobile, AL and each one is an unique solution to the wide range of roof types and their drainage challenges. You should look at the kind of roof, its dimensions, and its roof pitch to be able to choose the right drain. You also should think about the site of the drain, what amount of rainwater is expected and safety when selecting a roof drain for a house or business structure.

Gable, dormer, mansard and hip roofs shed water due to gravity. Flat roofs, on the other hand, collect rain water. Unless this water is guided out and away from the flat roof structure, it will most likely develop pools of water that could eventually leak and the amassed weight will eventually cause damage to the structure. That is the reason that roofs with a pitch of under two percent should have roof drains situated in the lowest areas on the roof in which water pools and need to be evenly spaced all throughout the roof surface.

Types of Roof Drains


There are several distinct variations of roof drains. They generally fall into two categories: flat roof drains and pitched roof drains. Pitched roof drains usually comprise gutters that accumulate rainwater that passes via gravity down to the roof edge. Gutters transport this water in the direction of downspouts which route the water flow down and away from the building or in to sewers. Flat roof drains can be one of three main types: scuppers, inner drains or siphonic drains.

Roof Rainwater Drain Scuppes


Scuppers are located on a roof's periphery. Scuppers can also be put in on a balcony or terrace. Small holes are cut in the side of the roof structure so that rain water can empty and drain the roof surface. Scuppers can connect to a downspout, or could be lengthened to make sure that water is directed away from the structure sides and foundation.

Inner Roof Drains


There are many types of inner drains for flat roofs. These are installed at low areas on the roof and connect to interior drainage pipes that route water outdoors or in to a sewer system. Many models of internal roof drains have domes, strainers or covers that keep debris from clogging the roof drain pipe. These types of drains operate via gravity funneling standing water through the roof drain system. They are constructed from PVC, cast iron or cast aluminum.

Siphonic Roof Drains

Siphonic roof drains are a more efficient alternative to gravity drainage. Conventional flat roof drainage permits both air and water to enter the drain system creating pipe space which is occupied by both air and water. By adding an engineered baffle to the sump of the drain system it creates a siphonic drain that eliminates air from the system and allows for smaller pipe diameters . When all air is removed, a negative air pressure in the tail portion of the drain is set up which attracts water off the roof siphonically. Though used primarily for flat roofs, siphonic drains can also be installed on pitched roofs.

If you need more information about flat roof drain or roof drain downspout in and around Mobile, Alabama, give us a call. We'd be glad to help.