The engineer should lay out the roof drain system consistent with the structural design strength of the roof.
Residential modern flat roof drainage.
Also known as low slope roofs flat roofs are less common in north american residential construction because the low slope of a flat roof has an increased tendency to collect water rather than shed like its more steeply pitched alternative.
A flat roof may use interior drains to collect water from the centre of the roof.
One of the most overlooked items on a flat roof is the draining system.
Inner drains gutters or scuppers each have their own function and deciding which system is best depends on the roof size slope or no slope and cost.
Your building and location can help determine which drain will fit your roof needs.
There are roof coating products available if there isn t enough slant or slope to accomplish this.
Unlike other roofing types that are slanted or sloped to allow water to drain automatically flat roofs need a built in drainage system to help remove moisture and debris.
There are four main types of residential drainage systems.
Poor drainage can lead to serious issues with flat roofing from leaks to structural damage.
These ditches guide water toward the eavestroughs.
Design load the water depth or build up would be limited to 3.
For flat roof drainage where you place your drains scuppers and the final material of the roofing is more important.
The angle is not significant enough to prevent water from pooling on the surface.
Surface subsurface slope downspout and gutters.
This will keep the load down to approximately 15 lbs.
This may make it less ideal for rainy or snowy climates.
Although not commonly used anymore the eavestrough drainage system is a good option if you have an older large industrial or commercial flat roof.
Inner roof drains are used on flat roofs and include a low section or channel that collects water and feeds it into a concealed drain that leads to an underground drainage system.
There are three types of drain systems commonly used on flat roofs.
Types of residential drainage systems.
For surface drainage to be successful ditches must be dug in a parallel pattern.
Each of these systems has its own pros and cons.
More attention should be given to the location of a drainage system to avoid future problems.
A gravity drainage system on a flat roof differs from the gutter system you find on residential roofs in two key ways.
The one challenge with flat roofing is ensuring proper drainage.
To keep damage like leaks from occurring water should not stand on a flat roof for more than 48 hours.
Inner drains are resistant to freezing but can require careful maintenance to prevent problems.
These drains are like the drain at the bottom of your shower except that the roof drain has a larger strainer to protect it from debris.
The main benefit of inner drains is that the system is hidden from view.
Of course the best designed flat roof has the correct amount of pitch to drain the water off naturally.
