“If the issue has already pushed down
into the building, often a pest management professional is the best option,”
Black recommends. “They can utilize
baits in a targeted way to reduce the
populations to levels that can then be
managed with non-chemical techniques.
The important piece to keep in mind is
to inspect regularly so that issues do
not get so high that they need chemical
4) Use Integrated Pest Management
Integrated pest management (IPM),
which prioritizes prevention strategies
over reactive ones, favors low-impact
methods to address pests. This includes
no-kill traps, sealing cracks in the envelope, anti-roosting devices, and the like.
Consider that one of the benefits of a
green roof is its ability to filter pollutants
from rainwater – you don’t want to be
adding more chemicals, stresses Curtis.
Pesticides can be used in limited applications when other methods haven’t
addressed the issue.
Beyond a good inspection program,
be proactive about the landscaping, says
Copps. Work with your roof provider to
ensure plant selection is appropriate for
your region and minimize species that
attract common pests.
“Inspects plants and potting soil for
pests before they are planted there,”
Black recommends. “Keep mulch levels
fresh and to a minimum.”
Curtis recalls a project where he hap-
pened to notice a colony of ants in the
soil that was destined for the roof. He
was able to head off the issue and new
mulch was ordered, but the story goes
to show that humans may be responsible
for inducing a pest to a site.
“Keep the plants healthy,” advises
Black. “If they become infested with
aphids, for example, then ants will be
especially attracted and establish colo-
nies.” This includes typical strategies like
trimming and pruning. Because veg-
etated roofs are typically modular, you
may simply be able to replace the soil
medium in an affected area if the issue is
contained, adds Curtis.
You should also be mindful of over-
watering. Ponding water is an ideal
place for mosquitoes to lay eggs and
overly moist soil can be attractive to a
variety of insects. Resolving this issue is
as simple as keeping irrigation levels in
If your roof is accessible to the public,
make sure to offer trash bins and empty
them on a daily basis, suggests Copps.
You should minimize the use of lights at
night as well, Black says, a move that will
also reduce energy costs.
There’s no reason you need to
abandon plans for a vegetated roof just
because there’s a possibility a few pests
might make their home there. Simply be
proactive about inspections and low-impact treatments so your green roof can
provide years of eco-friendly service.
Jennie Morton jennie.morton@buildings.
com is senior editor of BUILDINGS.
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