The course of a certified insulation product

The tests used to assess an insulation product depend on its nature and sometimes involve specific pre-test conditioning. A range of different tests may be used, but those that focus on its thermal insulation capabilities remain central to the process.

The process begins in the production plant, where the CSTB or LNE auditor takes samples of the products concerned. The samples of insulation product are sent to the laboratory, where they are stored until testing in an air-conditioned storage facility at a constant temperature of around 23°C in accordance with current standards.

The first stage consists of 'identifying' the product. So to measure its level of standards compliance, all the physical characteristics for this type of product are measured: its dimensions, density and thickness. a

The next stage is for the operator to prepare the specimens for individual tests. The number of specimens used depends on the tests to be applied to the product. Several specimens are required to make a statistical calculation and deduce a representative value from that calculation. The dimension and shape of specimens used vary depending on the type of test: cylindrical for the moister transfer test and parallelipedic for the other tests.

The tests then begin, although it may be necessary to subject specimens to pre-test conditioning. Where this is the case, conditioning may take the form of drying the product, humidifying it or even subjecting it to accelerated aging. b

Thermal testing

Naturally, thermal performance tests remain central to ACERMI certification. The specimens, which may or may not have been aged in advance (depending on the type of product), are loaded into heat flow meter apparatus and subjected to a temperature gradient between the two faces. Measurements of the heat rate transmitted from one side to the other, and the temperature difference between the two faces, form the basis for determining the thermal resistance of the insulation product. c

Mechanical testing

These tests aim to assess mechanical performance of insulation product under a range of mechanical loads that may affect the insulation product when installed in the building (traction, compression and creep over time). For example, insulation product installed beneath concrete screed is submitted to compression and creep testing. Creep testing aim the determination of insulation product strain over time when installed in building floor. It consists of subjecting the insulation product to a constant load over a period of several months, measuring the resulting deformation and extrapolating the results to achieve a 10-year value. d e

Other tests

The insulation product is also subjected to other tests that simulate the conditions it will encounter once installed. Sometimes, the installed insulation layer is exposed to moister transfer, or sometimes to direct contact with liquid water: the tests to measure the moister rate transfer and its performance when totally or partially immersed in liquid water reproduce the real-life conditions that the insulation material may encounter under such circumstances. The dimensional variations of the product are also tested and categorized to help users choosing the right product for the right installation. f g h


Loose fill products are subjected to three to four month settling tests including accelerated temperature and humidity cycles that simulate product installation conditions in 0.6 m x 0.6 m bins.

Once all the tests have been completed, a test report is compiled. This report is then forwarded to the certification manager, who compares the test values obtained with the values claimed by the manufacturer. ACERMI then decides whether to issue (or renew) the certificate. When the outcome is not as expected, ACERMI notifies the manufacturer accordingly.

ACERMI imposes around thirty sanctions per year, ranging from an additional audit to permanent suspension of certification.

(*) ISOLE classification:

  • I: Mechanical properties under the effects of compression
  • S: Resistance to differential movements
  • O: Water resistance
  • L: Mechanical properties for cohesion and bending
  • E: Ability to withstand water vapor

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