MIL-HDBK-1001/SA
Section 8: PROTECTED MEMBRANE ROOF SYSTEM
8.1 Description. The protected membrane roof system (PMR), also known as the "IRMA" roof, or inverted roof membrane
assembly, reverses the positions of membrane and insulation in the conventional built-up membrane roofing system. Instead of its conventional exposed position atop the insulation, a PMR membrane is sandwiched between the insulation above and the deck below. A PMR, from bottom up, may include the following components:
a) Deck;
only);
b) Suitable underlayment leveling board (steel decks
c) Additional layer of insulation (optional; for energy savings; may be tapered to improve slope to drain);
d) Membrane;
e) Percolation course (optional);
f) Insulation;
g) Filter fabric;
h) Ballast (aggregate or pavers).
8.2 General Design Recommendations
8.2.1 Structural Capacity. First consider the structure's load-carrying capacity. There must be structural capacity to carry the additional ballast or paver dead load required by this system.
8.2.2 Slope. Slope deck and membrane a minimum 1/2 inch per foot (4 percent) for new construction.
8.2.3 Water-Test. When practical, require that roofer water- test completed membrane before installing insulation and
surfacing with special attention to expansion joints and flashings. Leaks generally occur under expansion joints, flashings, and at embedded edge metal.
8.2.4 Climate. PMR's are well-suited to cold climates, as the membrane doubles as a vapor retarder. The best location for
30
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business