R Value Roof Membrane

Sprayed polyurethane foam spf will have an r value of 7 14 when it is newly installed.

R value roof membrane.

R value table for roofing materials and building insulation. After it ages a few months the r value will reduce to somewhere around 6 88. The average r value for some common roof materials include. Effective r value the fasteners used to attach insulation boards and single ply membranes act as thermal bridges so that the design r value is reduced to an effective r value.

Roof insulation design generally when a designer specifies an insulation he or she may request that the roof insulation provide a minimum r value or when a sloped system is installed that the insulation meet an average r value. Always check with your local code authority. In construction the r value is the measurement of a material s capacity to resist heat flowfrom one side to the other. Both types have an r value ranging from 4 r to 6 r per 1 inch of insulation thickness.

Gaf analyzed membrane samples from roofs across the us and studied thickness over scrim surface cracking and the ability to repair aging tpo membranes. Olson has calculated the percent reduction from design r value to be up to 29 percent. Please note that the r values for roof membranes shingles tiles air films and roof deck materials might or might not be permitted by your local code to be included when total roof assembly r value is being calculated for the purpose of satisfying energy code requirements. Location of r value on a product data sheet.

The higher the r value the better a material performs as a thermal insulator. A recent study of everguard tpo roofs installed between 8 and 16 years ago found they all performed above astm standards for newly manufactured tpo. The membrane is attached using 12 o c. For example while optimum performance using a black membrane the assembly must utilize insulation with an r value of 29.

Commonly used in inverted roof membrane assemblies irma. Quite the contrary in colder regions ashrae zones 4 through 8. To calculate the r value of a roof system your contractor will take into account the underlayment coverboards adhesives insulation and even the membrane. In simple terms r values measure the effectiveness of insulation and a higher number represents more effective insulation.

R value is used as a measurement of the effectiveness of thermal insulating materials. For white and black membranes the table outlines the necessary adjustments in r values to maintain a roof assembly s energy performance.