Project1_Layout 1 07/05/2013 FLAT ROOFING & WATERPROOFING SYSTEMS
A fl at out approach to urban drainage
With the geographical footprint of UK cities increasing at an unprecedented rate year-on-year, the issue of surface water run-off, and its
knock-on effects, is fast becoming a major concern for developers, as Phil Windus at ACO Water Management, explains
In urban areas, huge swathes of land have been
paved over or built on, making it much harder
for water to naturally soak away in to the
ground. While cities grow and the space for
housing reduces, the need for more suitable
drainage solutions is more pressing than ever.
Focusing on urban areas in particular, there
is an increasing demand for fl at roofs, balconies
and roof terraces. As forecasted by The Flat
Roofi ng Market Report – UK 2017-20211 fl at
roofs are expected to rise at a steady pace. They
can provide developers with fl exibility both
in planning and design, for example; roof-top
gardens or ‘green roofs’ are especially popular in
urban spaces – adding a refreshing touch of the
natural world to a house or apartment.
Flat roofs are also much easier to construct
than pitched roofs and can enhance the natural
lighting for a building, along with many other
benefi ts for the owner, such as energy savings.
Previously people may have assumed that
fl at roofs present a variety of water management
challenges, due to their design. However, with
the help of modern waterproofi ng solutions,
fl at roofs now offer the ability to store water
temporarily. Attenuating roof drains can store
rainwater on a fl at roof and help to reduce the
impact of heavy storms by draining away slowly
over a few hours.
Further to this, it is now possible to use
this water for non-potable applications in the
building. Attenuating drains are able to fi lter
and treat the rainwater so it can be distributed to
tanks inside bathrooms, for example. This makes
it a zero-energy rainwater harvesting system that
provides a sustainable urban drainage solution at
076 MAY 2018 RCIMAG.COM
the same time.
As such, drainage is one of the key
components for developers to consider, and a
high performance roof outlet is an essential
item for fl at roofs. However, there are also a
number of factors that should be accounted for to
determine the correct product for the project.
1: Understanding weather patterns
In order to advise customers on the most
appropriate roof outlet, the geographical location
and rainfall intensity must be considered fi rst
and foremost. This will help to establish the
amount of surface water run-off and the type of
outlet that is required.
2: Bear in mind the catchment area
The next factor is to identify the catchment area
of the roof, as this will help to defi ne the correct
product for the job – both in terms of size and
style. For example, ACO’s angled roof outlets are
particularly suited for more complex pipework,
all while keeping in mind the risk category of
the building and the hydraulic capacity of the
drainage system employed.
3: Ensure it is built to last
As roof outlets will be exposed to all types of
weather, it is essential that the outlet specifi ed
is manufactured to the highest quality standards
and is resistant to the outdoor elements, all
while delivering high-performance rainwater
drainage. Units from ACO’s rainwater outlet
range, for example, are made from marine-grade
aluminium alloy and powder-coated to ensure
high corrosion resistance, while 304 stainless
steel fi xings are used to support long service,
durability and reliability.
4: One size doesn’t fi t all
Flat roofs are often associated with a set of
challenges, and the specifi cation of the correct
drainage to each individual installation is
essential. All projects are different from one
another and there are drainage outlets that
are more appropriate for some projects than
they are for others. The balcony spigot, for
example, offers a discrete solution for balconies
and walkways, whereas the two-way outlet is
ideally used wherever horizontal and vertical
surfaces meet. For projects where an existing
roof is being upgraded, the refurbishment outlet
is designed to fi t inside the current unit and
pipework, ensuring minimal disruption to the
current rainwater system.
4: Offer advice
Frequent and thorough fl at roof maintenance is
essential to maximise longevity, so the best thing
to do is to offer expert advice to the owner of
the property to ensure it is properly maintained.
Like all drainage systems, it is absolutely vital
that they are free from debris in order to function
properly. Checking the gutter and outlets four
times a year is a good benchmark to set. This
will also offer homeowners the chance to ensure
the roof area and membrane are still intact.
Flat roofs are becoming not just an
architectural necessity, but the desired
alternative – especially in urban developments.
With this trend set to grow, roofers are best
placed to provide advice on the important role
that drainage plays in fl at roof applications.
It is essential that roof outlets are resistant to outdoor elements, in addition to delivering high-performance
Outlet is ideal for