Thermal transmission testing is an important part of the evaluation process for a product to make its way from the manufacturing plant onto retail shelves.

ASTM C518 is the Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus.  Whether you manufacture polyiso boards, batt insulation, spray foams, or any number of other construction materials, it can be important to understand the thermal performance of your product through an R-value rating.

What is an R-value and Why is it Important?

R-value is the capacity of an insulating material to resist heat flow. In theory, the higher the R-value, the greater the insulating power and contribution to energy efficiency. Energy conservation is a “hot” topic. With LEED standards and state-wide energy codes becoming more popular, your product’s R-value has never been more important.

How Do You Test for R-Value?

The heat flow meter apparatus is comprised of a hot plate and a cold plate. When your product is placed in between the two plates, our test equipment measures the heat flow from the hot plate through your product and to the cold plate. The measured resistance of heat flow between the two plates is your product’s R-value (thermal resistance value).

Rising Standards of Energy Codes

California has been leading the charge in passing the nation’s strictest green building codes with its Title 24 standards.  The energy-saving state-wide code is greatly reducing greenhouse gas emissions.  Other states are looking to California as they create their own energy standards.

From Title-24 2016 update:


    1. External insulation with an installed R-value of at least R-12; or
    2. Internal and external insulation with a combined R-value of at least R-16

Why Choose NTA for Thermal Performance Testing?

NTA is a family-owned and -operated company that prides itself on being staffed by customer-oriented technical experts. Manufacturers choose to partner with NTA because our full suite of services increases speed to market. In most cases, we can provide ASTM C518 test results within 2 weeks. NTA cares about the quality and safety of the products it tests, inspects, and certifies because we understand that these products have an impact on people throughout the world.

For more information please contact Justin Mann at 574-773-7975 or send in a request for information here.