Green Roofs - Living Architecture Monitor - Winter 2019 - 31

"ZEPPELIN DEVELOPMENT'S FLIGHT BUILDING IN THE DENVER
RIVER NORTH DISTRICT HAD HUNDREDS OF THOUSANDS OF
DOLLARS WORTH OF DAMAGES ON THE MEMBRANE ROOFING
YET ITS TWO GREEN ROOFS SUSTAINED NO DAMAGE."
- OLIVER GILLINGS-PECK

causing a massive hailstorm.
The resulting cost amounted
to over $1.4 billion in damages. This particular hailstorm
was classified as severe due
to the golf ball sized hail;
however some rooftops located
in the storms path sustained
little to no damage at all. Zeppelin Development's Flight
building in the Denver River
North district had hundreds
of thousands of dollars worth
of damages on the membrane
roofing yet its two green roofs
sustained no damage. Kyle
himself admitted in a local
news interview that the green
roof had more than paid for
itself as it provided adequate
hailstorm protection. Andy
Creath, a Green Roof Professional in Denver reported that
green roofs located on two
separate university campuses
LIVINGARCHITECTUREMONITOR.COM

reported no damages during
the hail storm on their 17000
sf and 3000 sf green roofs.
Other than specific examples
of green roofs withstanding hailstorm damage it seems almost
intuitive to assume that a green
roof would function well as a
material that would not be damaged by hailstorms. This is because the velocity of a hailstone,
that is to say its amassed speed
built up from being dragged
down to earth by gravity, is effectively absorbed and dispersed
when the hailstone hits the
growing media. Growing media
has a relatively low density and
because of that, it can absorb
the impact of the hailstone.
The average green roof has
four to six inches of growing
media that acts as a barrier and
helps absorb the impact as well
as a drainage layer which also

protects the membrane. A metal or asphalt roof has a much higher
density which means that when a falling hailstone hits the roof the
energy from the hailstone is released in a much more concentrated
and violent manner as two dense objects are colliding.
While installing a green roof will add additional costs upfront,
in the long term it provides building owners with a long list of
benefits that save them on energy, replacement and maintenance
costs. Hailstorm protection should be added to the general list
of benefits associated with installing a green roof on buildings
in Hail Alley. The next step is for scientific research to be done
about which types of green roofs provide the best hail protection
and to determine whether or not a green roof has a class four
UL2218 rating or even better.
Oliver Gillings-Peck is a researcher and freelance writer.
Resources
https://www.cbsnews.com/news/hail-damage-costs-this-year-could-hitnew-annual-high-in-u-s/
https://www.denverpost.com/2017/05/23/hailstorm-costliest-ever-metrodenver/
https://www.nssl.noaa.gov/education/svrwx101/hail/
https://www.washingtonpost.com/news/capital-weather-gang/
wp/2018/08/08/costly-hailstorms-are-rapidly-increasing-heres-what-theweather-community-is-doing-about-it/
LIVING ARCHITECTURE MONITOR / WINTER 2019 / 31


https://www.cbsnews.com/news/hail-damage-costs-this-year-could-hit https://www.denverpost.com/2017/05/23/hailstorm-costliest-ever-metro https://www.nssl.noaa.gov/education/svrwx101/hail/ https://www.washingtonpost.com/news/capital-weather-gang/ http://www.LIVINGARCHITECTUREMONITOR.COM

Green Roofs - Living Architecture Monitor - Winter 2019

Table of Contents for the Digital Edition of Green Roofs - Living Architecture Monitor - Winter 2019

Table of Contents
Green Roofs - Living Architecture Monitor - Winter 2019 - IP
Green Roofs - Living Architecture Monitor - Winter 2019 - Cover1
Green Roofs - Living Architecture Monitor - Winter 2019 - Cover2
Green Roofs - Living Architecture Monitor - Winter 2019 - Table of Contents
Green Roofs - Living Architecture Monitor - Winter 2019 - AD1
Green Roofs - Living Architecture Monitor - Winter 2019 - 1
Green Roofs - Living Architecture Monitor - Winter 2019 - 2
Green Roofs - Living Architecture Monitor - Winter 2019 - 3
Green Roofs - Living Architecture Monitor - Winter 2019 - 4
Green Roofs - Living Architecture Monitor - Winter 2019 - 5
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Green Roofs - Living Architecture Monitor - Winter 2019 - 34
Green Roofs - Living Architecture Monitor - Winter 2019 - Cover3
Green Roofs - Living Architecture Monitor - Winter 2019 - Cover4
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Green Roofs - Living Architecture Monitor - Winter 2019 - 43
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