Dow Protected Membrane Roof EN - Manual (Page 4)

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Overview
C H A N G I N G T H E S E Q U E N C E
Advantages of PMR
All flat roof assemblies consist
of the same basic elements
assembled in a seemingly logical
order: a deck (composed of wood,
metal or concrete), covered with
insulation and topped with a
waterproofing membrane. A
protected membrane roof can
employ the same elements, but
the membrane is positioned
under the insulation, offering
superior long-term performance
and durability.
PMR assemblies:
• Maintain the membrane at a
nearly constant temperature,
close to the temperature of
the building’s interior; this
minimizes the stresses on the
membrane by reducing the
harmful effects of freeze-thaw
cycling, thermal cycling and
excessive heat
• Protect the membrane from
weathering, foot traffic and other
types of physical abuse – both
during and after construction
• Allow year-round construction
since the roof is waterproofed
first, then insulated
• Permit easy removal and re-
installation of the ballast and
insulation for making repairs
or for constructing additional
stories. In addition, a protected
membrane roof provides an
environmentally preferred
option to reuse the insulation
• Allow for a range of ballast
options – stone, precast paving
slabs, green roof, interlocking
stone or concrete – depending
on use and aesthetic
considerations
• Are compatible with a range
of membrane types
• Eliminate the need for a sepa-
rate vapor retarder
PROVIDE DURABILITY
AND PROTECTION
With the membrane positioned
under the insulation, the choice
of insulation becomes an impor-
tant consideration. The insulation
must be able to withstand wet
environments (without sacrificing
insulation performance) and
foot traffic during and after
construction, while continuing
to perform over time.
Because of its durability and
outstanding moisture-resistant
qualities, STYROFOAM
™ extruded
polystyrene insulation delivers
exceptional performance in
roofing and plaza applications.
• Provides excellent moisture
resistance and long-term
R-value*
• Offers exceptional durability
to extend the life of the plaza
or roof
• Protects the membrane against
weathering, physical abuse
and damage
• Maintains the membrane at a
relatively constant temperature
• Controls dew point location
*R means resistance to heat flow. The higher the R-value, the greater the insulating power.