Dow Protected Membrane Roof EN - Manual (Page 3)

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Protected membrane roofing’s
breakthrough contribution to
flat roof technology was the
incorporation of an “upside-
down” approach to insulating
the roof: placing the insulation
on top of the waterproof mem-
brane to improve the membrane’s
effectiveness and the insulation’s
efficiency.
This advancement was made
possible in large part by the use
of STYROFOAM
™ extruded poly-
styrene insulation, whose
closed-cell, water-resistant quali-
ties have proven to be a key
component in protected mem-
brane roof (PMR) systems.
A conventional roof places
the membrane on top of the
insulation, leaving the mem-
brane vulnerable to extreme
temperature changes, freeze-
thaw conditions and physical
abuse from heavy foot traffic
(Figure 1).
The PMR system places the
insulation on top of the mem-
brane, protecting the roofing
membrane from extreme tem-
perature changes and physical
abuse (Figure 2).
The main difference between
PMR and conventional roofing
is the sequence in which the
materials are applied. The key
to the PMR system is that the
insulation is placed on top of
the waterproofing membrane.
This configuration protects the
membrane, resulting in superior
long-term performance and
durability.
Figure 1: Conventional Roof With Membrane Above
the Insulation (depending upon building and climate
conditions, a vapor barrier may also be used)
Figure 2: PMR With Membrane Below the Insulation
Ballast
Filter
Fabric
STYROFOAM™
Extruded
Polystyrene
Insulation
Membrane
Deck
Membrane
STYROFOAM™
Extruded
Polystyrene
Insulation
Deck
Overview
C H A N G I N G T H E S E Q U E N C E