Flat Roof Drainage Problems
There are a number of factors that can cause these problems.
Improper roof slope:
Drains not installed in a sump can cause the drain ring to block drainage enough to create a 2’ by 2’ puddle of standing water. In
turn, the standing water will accelerate the collection of debris on the roof surface which will cause the standing water volume to continually
increase until maintenance is performed and the debris is cleared away.
What is common is cleaning the drain only well enough to allow the backed up water to drain and not removing the debris from the roof which will
wash back to the roof drain and cause an obstruction to the drain again.
Primary and/or secondary drains installed at the wrong elevation. If both the primary drain and overflow drain are installed at the same elevation
in one sump. The risk for the roofing contractor to install the wrong drain ring and water dam on the wrong drain is quite high. The secondary
drain installed at too low of an elevation will cause almost permanent ponding of water around the drain
Light duty parts:
Plastic parts are a problem because in most cases the plastic parts do not last as long as a typical roofing system so the plastic parts crumble
and fall into the drains and clog the drains or blow away and the drain is unprotected until the roof is replaced. Light duty parts are not necessarily
a problem during the first roof system if they survive the installation. The problem arises at reroof time. This is when the drain will be damaged
from the roof removal and if it needs to be replaced the cost will be in the $1000 to $1500 range or higher depending on the access to the drain
from the interior of the building.
Every penetration is a possible leak in a flat roofing system. The common design today is to use two drains to provide primary and secondary drainage
which in turn creates two penetrations in the roof membrane.
Verifying that the roof drains primary and secondary are installed at the proper location and elevation before the roofing system is installed.
Create a proper maintenance program and schedule to prevent blockage of the drainage system.
Provide quality fixtures and parts to do the job intended.
Froet Drain® roof drain solution:
Froet Industries Bi-functional combination roof drain is designed to solve many of today’s roof drainage problems purely by its innovative
design. During installation, it is easier to install due to its single fixture design and the need to only verify the low point of the roof to
install the drain. Having to know the overflow elevation is no longer necessary due to the two-in-one design of the Froet Drain® roof drain.
The drain shows up on the jobsite with the specified overflow elevation parts. Froet Drain® roof drain is built with durability and high quality
as its design priority. It will last through multiple reroofs. With its design of two in one it reduces penetrations in half in comparison to the
common two drain installation.
Froet 6000 & 7000 Flow Sensors:
It is a low voltage sensor that monitors flow through the overflow system to alert the building owner of a primary system blockage. The flow sensor
will serve as a backup to the maintenance schedule.
See also: Roof Drain Ponding