Green Roofs - Living Architecture Monitor - Spring 2018 - 31

BLACK ARTS

KEY LESSONS LEARNED FROM OVER 60 YEARS OF
ROOFING, 45 YEARS OF PLAZA WATERPROOFING
AND 20 YEARS OF WATERPROOFING GREEN ROOFS
BY TIM BARRETT

Keeping the moisture out of a building is far from the most sexy or
thrilling aspect of designing a green roof (for most people) but it still
remains absolutely critical to the success of any green roof project.

ailure to keep the water out and where
it belongs can cause significant, ruinous
costs both during and after installation
of a green roof besides discouraging
development of other green roof projects.
A properly designed, installed and maintained green roof will last longer than brick
and mortar. If an installation is anything
less than it could be, it can jeopardize a

major green roof benefit of extending the
life expectancy of the waterproofing system.
Sustainability in roofing is, in large part,
making things last longer and sending less
waste to the dumps.
My experience with actual installations,
manufacturing, consulting, chairing and coauthoring two RCI eight hour green roof
courses, speaking at numerous Green Roofs

Select a reputable manufacturer with a proven waterproofing system
capable of lasting for a long time and with a track record of use with
green roofs. Putting inexpensive or unproven waterproofing under a
green roof assembly is risky and an unwise choice.
Waterproofing is distinguishable from weatherproofing as defined in
NRCA and RCI glossaries, among others. Know the difference and only
use real waterproofing under green roofs.
Putting insulation under a waterproofing membrane is less than
optimum design and compromises the longevity of a green roof.
Insulation is best placed above the membrane.
The waterproofing system should provide total adhesion to the
structural deck or at the least, very limited containment in order to
eliminate untraceable moisture migration across roof decks.
Membranes tenaciously adhered to the structural deck stop belowmembrane water migration and make it far easier to locate and repair
any leakage or damage should it occur.
Structural Concrete decks are preferable to steel and wood decks.

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for Healthy Cities conventions, my appreciation of biophilia and of excellence in
general have taught me many lessons which
may be instructive for anyone involved
with green roof design or installation. As
green roof markets continue to grow, the art
and science of green roofs will continue to
evolve. My evolution to date has taught me
the following:

Irrigation considerations appear more important than the industry
originally thought.
A low-slope drainage gradient is often not provided but remains highly
desirable.
Ensure the waterproofing membrane can repel plant roots or that a FLL
approved root barrier is used to protect the waterproofing membrane.
Reasonable design considerations for water accessibility and
pedestrian safety are necessary.
Select and prequalify experienced contractors to install the
waterproofing and vegetation.
Roofing is hard work conducted in harsh environments. Having an
experienced and dedicated installation team is a major key to success.
Remain mindful of changing code requirements and the various load
factors.
Chose a Team Leader who understands the macro picture, a Green
Roof Professional (GRP) being a good place to start.

LIVING ARCHITECTURE MONITOR / SPRING 2018 / 31

http://www.LIVINGARCHITECTUREMONITOR.COM

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Spring 2018