The proper design and installation
of a Greenroof-Roofscape is more complex and challenging than
a typical roofing or waterproofing project. Also more rewarding.
In the early phases of the
project, the structural engineer must provide guidance for allowable
loading design; a Landscape Architect or a horticulturalist
is retained to provide vegetation criteria and design
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Low
profile planting
systems with plants less than 24 inches tall
are generally designed with a single layer
application of root protection.
High Profile
plantings, in excess of 24 inches in height,
or plantings known to have aggressive root
systems, a thicker or multiple layers of root
protection is generally installed for extra
protection.
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Barrett will provide the necessary
moisture and thermal protection design criteria and facilitate
coordination between the design fractions.
Basic plan design requirements
include leaving a twoor three foot wide perimeter at all perimeters
and roof projections, free and clear of soil and vegetation.
These clear areas are curbed and covered with concrete pavers,
walkways or stone ballast.
Most Greenroof Roofscapes
do not need to be irrigated. If Roofscape systems are not irrigated,
a water supply should be furnished. Non-irrigated systems also
require firebreaks, 2-3 feet wide, at 100 foot intervals in
all directions. The firebreak areas are treated similar to the
perimeters, with pavers or aggregate surfacing.
Vegetation planting designs
are classified as High Profile (Intensive) and Low Profile (Extensive).
Vegetation choices are best chosen from the alpine, arid or
indigenous species. Roof vegetable gardens are another viable
high profile choice.
Greenroof — Roofscapes require
a maintenance commitment commensurate with the planting design
in addition to a standard roof maintenance program.
Without such a commitment the
Greenroof-Roofscape will not realize it’s full potential.
