Summer '22

expensive problem to rectify!
It follows therefore, that keeping the
vegetative layer of a green roof in
good condition is key to maintaining or
even enhancing that roof’s benefits to
humankind.
What is involved in maintaining an
extensive green roof?
• Maintaining the structural features that
influence green roof performance such
as drainage outlets and irrigation systems
• Regular testing of fall restraints
• Removing debris and unwanted plant
material
• Fertilisation - although this does not
apply to all living roofs
• Managing the balance of species
growing on the roof
Each living roof will of course be slightly
different in its maintenance requirements,
and ideally, care will be taken to plan and
budget for maintenance at the design
stage. However, the basic principles are
very similar for any and every extensive
living roof.
Maintaining an extensive green roof
should have a two pronged approach.
First, it’s vital that the green roof
infrastructure is maintained. This, after
all, is what creates the plants’ living
conditions. Drought loving plants will not
survive on a soggy roof any more than
they would in a terrestrial bog garden.
Secondly, the needs of the plants must
be met. Removing the competition from
unwanted plants and ensuring that
desirable plants have everything they
need in order to thrive is key to a healthy
living roof. Understanding which green
roof systems need extra support through
fertilisation is an art form in itself. Your
installer should give you some guidance,
but as a rule of thumb, extensive green
roofs with a good depth of substrate and
a population of wildflowers need fewer
additional nutrients than a sedum roof.
How often are
maintenance visits
required?
For best
practice, an
established
extensive
living roof
should have
at least two
maintenance
visits per
year. Ideally,
one in the spring
to check that
plants are recovering
well from the winter and
that drainage outlets are fully
functional. And a further visit in autumn
to clear debris and unwanted plant
material.
For a recently installed living roof,
the Green Roof Organisation (GRO)
recommends that the installing
contractor take responsibility for it during
the establishment stage.
Is green roof maintenance
expensive?
A better question would be “what
is the cost of neglecting green roof
maintenance?” Just like any other
housekeeping tasks, there will be a cost
to green roof maintenance. However,
Granny always said that ‘a stitch in time
saves nine’ and she was right. The cost
of removing a forest of young trees
from your green roof and then repairing
root damage to your waterproofing
far outweighs the cost of regular
maintenance visits.
If you think of green roof maintenance
as an investment (or an insurance) rather
than a cost, it doesn’t seem expensive at
all. After all, would you buy an expensive
car and never service it?
Aside from the environmental and
architectural value of a living roof, the PR
opportunities are immense but all three
of those benefits could be jeopardised
by an inadequate
maintenance regime.
Regular
green roof
maintenance
anticipates
and
negates
any
possible
issues, and
just like
any good
housekeeping
is a more cost
effective way of
managing the needs of
the building and the ecosystem
it supports than waiting until something
goes wrong.
Does green roof maintenance require
special training?
Green roofing, as an industry is unique.
Anybody designing or maintaining a
living roof needs a good understanding
of the engineering and technology
that supports the vegetation. At the
same time, they also need a thorough
knowledge of horticulture and ecology.
Green roof maintenance is not a job
for a gardener, nor for a roofer, but for
someone whose skills set spans the
two industries. Specialist training can
be arranged through GRO or Lantra.
For more information, visit https://
greenrooforganisation.org/green-rooftraining/
You will also find a wealth of information
about green roof maintenance
in the GRO Green Roof Code.
Download it for free from https://
greenrooforganisation.org/downloads
Contact
GRO
www.greenrooforganisation.org
Tweet: @RoofGro
www.greenscapemag.co.uk • GREENSCAPE SUMMER 2022 19