A protected membrane roof places the rigid insulation and ballast on top of the waterproofing membrane, reversing the traditional order. This design shields the membrane from ultraviolet radiation, extreme temperature fluctuations, and physical damage from foot traffic. It is commonly used on flat roofs and plaza decks where long-term durability is prioritized.
We're going with a PMR design for the hospital addition so the maintenance crews don't tear up the membrane walking to the chillers.
Because the membrane is buried under insulation and ballast, locating a leak in a PMR system requires specialized electronic leak detection before the overburden is removed.
Also heard as
- protected membrane roof
- IRMA roof
- inverted roof assembly
Related terms
Protected membrane roof
A roofing assembly where the waterproofing membrane is installed under the thermal insulation and ballast.
Plaza deck
A waterproofed structural slab over occupied space, topped with pavers, soil, planters or a wearing slab.
Single-ply membrane
A flexible sheet of compounded synthetic materials used as the primary waterproofing layer on flat roofs.