Johns Manville Helps Customers Understand Changes to LTTR Test Method and Values

Johns Manville (JM), a leading supplier of commercial roofing products, advises customers of revised LTTR (Long-Term Thermal Resistance) values for its polyisocyanurate insulation product line.

To help educate the industry and ease the transition to the new test method and change in LTTR values effective January 1, 2014, JM has prepared a packet of information detailing the updated specifications.

As part of the current ASTM C1289 standard for polyiso, products must meet R-value requirements, presented as LTTR, pertaining to how foam ages over time. The LTTR test is a technically supported, more-descriptive measure of the foam’s in-service thermal performance.

“In the short term during this transition, there may be some confusion in the industry with regard to the planning, bidding and constructing of projects,” said JM’s M.J. Cusick, portfolio manager for Cover Boards and Insulation. “To get in front of this, we began notifying design professionals of the potential confusion in the third quarter of 2013, suggesting they specify polyiso insulation by its thickness rather than R-value during this transition.”

For jobs that will be permitted after January 1, 2014, JM advises that projects should be designed and bid using the new LTTR standard. The test method change typically results in an extra 0.1" of thickness per board or 4% to 6% more material/thickness, depending upon desired R-value.

To further support customers, JM will modify its packaging to reflect LTTR values by both test methods, beginning in the fourth quarter of 2013. As an example, a 1" board label will now include information from LTTR-S770-03: 6.0 (the old test method) and LTTR-S770-09: 5.7 (the new test method).

To learn more about the LTTR values transition and access an informational booklet, please visit the JM roofing website and click on the ‘LTTR’ banner, or contact a JM representative.

About Johns Manville

Johns Manville, a Berkshire Hathaway company (NYSE: BRK.A, BRK.B), is a leading manufacturer and marketer of premium-quality products for building insulation, mechanical insulation, commercial roofing and roof insulation, as well as fibers and nonwovens for commercial, industrial and residential applications. JM serves markets that include aerospace, automotive and transportation, air handling, appliance, HVAC, pipe and equipment, filtration, waterproofing, building, flooring, interiors and wind energy. In business since 1858, the Denver-based company has annual sales of approximately $2.5 billion and holds leadership positions in all of the key markets that it serves. JM employs approximately 7,000 people and operates 45 manufacturing facilities in North America, Europe and China. Additional information can be found at

Johns Manville Roofing Systems Sarah Tholen, 303-978-2858 Manager, Marketing Communications