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.

Quite the contrary in colder regions ashrae zones 4 through 8. For white and black membranes the table outlines the necessary adjustments in r values to maintain a roof assembly s energy performance. The membrane is attached using 12 o c. 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.

Mechanically attached installation uses heavy duty screws and barbed plates to hold the membrane down tightly and is not affected by possible iso de lamination. 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. Olson has calculated the percent reduction from design r value to be up to 29 percent. R value is used as a measurement of the effectiveness of thermal insulating materials.

To calculate the r value of a roof system your contractor will take into account the underlayment coverboards adhesives insulation and even the membrane. Always check with your local code authority. 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.

Pattern with perimeter sheets attached 6 o c. In construction the r value is the measurement of a material s capacity to resist heat flowfrom one side to the other. Location of r value on a product data sheet. Commonly used in inverted roof membrane assemblies irma.

For example while optimum performance using a black membrane the assembly must utilize insulation with an r value of 29. After it ages a few months the r value will reduce to somewhere around 6 88. 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.

In simple terms r values measure the effectiveness of insulation and a higher number represents more effective insulation. 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.