Page 646 - Handbook of Thermal Analysis of Construction Materials

614 Chapter 15 - Roofing Materials

(TPO) has entered the market. Polymeric membranes have advantages and
disadvantages. [8]
Advantages:

• Ultra-lightweight (for unballasted, adhered membranes)
• Adaptable to irregular roof surfaces

• Isotropic physical behavior
• Superior architectural quality (color)

• White membranes have general superior heat reflectivity
(for cooling-energy conservation)
• Better elongation (up to 800% at 21°C, 70°F)

• Superior performance at sub-zero temperatures [flexibil-
ity down to at least -40°C, (-40°F) for some materials]

• Easier application

• Fewer weather restrictions on application
• Less hazard from moisture entrapment during installation

• Easier repair of punctures, splits, tears
• Easier flashing applications at corners and irregular sur-
faces where stiffer built-up roof materials are difficult to
form
• Possible greater reliance on factory-manufactured mate-
rial quality

Disadvantages:
• Greater requirement for good workmanship

• More limited range of suitable substrates
• Less puncture resistance. Hence, greater vulnerability to
traffic damage

• Lack of performance and design criteria comparable to
those available for built-up roofs