<html><head><style>h1 {text-shadow: 1px 1px #111111;}</style></head><body><h1><p style="color:white"><b>Protected Membrane Roof</b></h1></body></html></p>


The longer-lasting roofing solution

A protected membrane or PMR roof (sometimes called an inverted or upside down roof) uses the same materials as a conventional roof but places insulation on the top of the membrane. Insulation boards are loose-laid over the membrane and then weighted down with gravel ballast, paving slabs, or soil in the case of “green” or vegetative roofs.

Invented in the late 1960’s, a protected membrane roof system uses DuPont Styrofoam Brand XPS Insulation to protect the membrane, helping improve the performance and longevity of the entire roof system.

Protected membrane roofs are becoming a popular alternative to conventional roofs because they are cost-efficient and energy-saving, improve occupant satisfaction, provide long-term performance and sustainability benefits, and increase community resilience.

A protected membrane roof system works because DuPont™ Styrofoam™ Brand XPS insulation is inherently resistant to moisture and durable enough to withstand prolonged exposure to the environment.

  • Resists water absorption
  • Provides long-term high R-value thermal performance
  • Is unaffected by freeze/thaw cycles
  • Withstands surface traffic
  • Provides long-term protection to the waterproof layer
  • Can be ballasted to prevent flotation
  • Protects roof layers from UV and mechanical damage

Explore products for protected membrane roofs.


Typical protected membrane roof assemblies

Ballast Roof

Ballast roofs are your typical protected membrane roof design. Rather than soil and vegetation or pavers, they use stone or gravel to hold the roofing components in place. A ballasted roof is durable, energy efficient, economical, and fast and easy to install. 

Green Roof

A green roof, also known as a vegetative or garden roof, is a protected membrane roof design that uses soil and vegetation to hold the roofing components in place. A green roof can lower cooling costs, reduce storm water runoff, promote biodiversity and improve air quality.

Blue Roof

A blue roof is a protected membrane roof design that helps manage storm water. It promotes lateral drainage, captures water for irrigation, and blends well with green roof assemblies. 

Paver Roof

Paver protected membrane roofs are durable and energy efficient. They add valuable rooftop recreation space. Additionally, paver PMR assemblies blend well with green and blue roof assemblies.


Information and ideas

Superior protection for low-slope commercial roofs
Tech Solutions 508.3: Ballast Design Guide for PMR Systems
Five reasons to choose an inverted roof
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