How do cascade leaf guards offer higher flow rates?
- Read time: 4 minutes
- Date: 11 Oct 2021
- Flat Roofing
A leaf guard protects gutters and drainpipes from becoming blocked. When it rains, debris can collect in the drainpipe and prevent water from draining.
Eventually, this could cause further problems on the roof of the building, with water pooling on top with nowhere to drain away. Lots of standing water may cause leaks in the roof to appear.
Leaf guards prevent rainwater pooling on the roof by keeping the pipes free of debris.
Why does the flow rate of the leaf guard matter?
High performance leaf guards prevent damage to the guttering. The faster the flow rate, the faster the water drains away from the roof.
How does a standard leaf guard work?
There are some differences between the types of leaf guards, and because of this there is some difference in the flow rates of each type.
A standard leaf guard works by draining the water down the insides of the drainpipe, leaving a space for air in the middle. At this stage, there is a completely free flow from the roof into the outlet.
The second stage occurs when the pipe hits capacity, and the outlet is drowned in excess water. In this stage, there is no space for the air to get into the drainpipe, resulting in the familiar swirling motion seen when draining a bathtub.
This type of drainage is much less effective than other options, with a slower flow rate and a rapid rise in water level collecting at the outlet.
Why does the flow rate of the leaf guard matter?
Flow rates refer to the amount of rainwater that drains from a flat roof normally expressed as litres per second (l/s). The type of leaf guard used will affect the flow rates.
A rainwater calculation should be carried out on all new buildings to determine the flow volume required.
What are Cascade high-performance leaf guards?
Fixfast offer a Cascade high-performance leaf guard which provides a high flow rate especially when used with a 110mm FarBo rainwater outlet.
Whilst using a high-performance leaf guard can be more costly in isolation, it is likely to result in savings overall as less outlets, downpipes and underground drainage will be required.
How does a Cascade leaf guard work?
Cascade leaf guards create a siphon effect. Water drops down the pipe, creating a single mass of fluid, causing a vacuum.
The vacuum sucks the water down the drainpipe much quicker than a standard leaf guard, meaning that the outlet doesn’t get drowned in water. This is a much more effective way of draining excess water on a rooftop.
