Fiberglass: Tried & Tested

Fiberglass insulation has a long history in the building industry. It was originally introduced to the market as a building insulation around 1932. Since that time, rigorous testing and standards have been established to ensure that the material performs safely within its intended applications. These tests have included everything from establishing performance characteristics to exploring impact of insulation glass fibers on human respiratory health.

As a result, fiberglass is one of the most tested man-made materials available, and many of the tests have become part of the standard requirements that must be met for the material to be used inside the building envelope. Below, we’ve outlined the details of the more common required test methods, as well as the voluntary testing that Johns Manville performed with third-parties to ensure that the fiberglass used in our building insulation complies with code requirements and is safe for manufacturers, fabricators and building occupants. We’ll be specifically addressing this research and the results in our live webinar,  “The Science Behind the Health and Safety of Fiber Glass and Mineral Wool,” on March 25th at 2:00pm ET/ 11:00am PT.

Flammability testing
ASTM E84:  Standard Test Method for Surface Burning Characteristics of Building Materials

ASTM E84 is a comparative test used to determine the burning behavior of a material based on the amount of flame spread and the amount of smoke that is generated during the test. This test is performed in a tunnel that is 24’ long and 20” wide. The specimen to be tested is mounted throughout the ceiling of the tunnel. The fire in the tunnel is supplied with natural city or bottled gas fuel of uniform quality. Before actual testing of the test specimen, the tunnel must first be calibrated using a very flammable red oak flooring and minimally or non-flammable fiber-reinforced cement board standards. The test specimen is given values in relation to the oak and cement standards. The end purpose of this test is to meet requirements that are put in place in building codes to protect occupants in buildings. For example, certain materials installed in a plenum or air handling space have a flame spread index of 0-25 and a smoke developed index of 0-50 (25/50 rating).

When it comes to fiberglass, the glass itself  will not burn; however, the binder that holds the glass together is organic in nature and, therefore,  has the potential to burn.

Thermal Performance Testing
ASTM C177 Standard Test Method for Steady State Heat Flux Measurements and Thermal Transmission Properties by Means of the Guarded Hot Plate Apparatus
ASTM C518 Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus

These two test methods are used to measure the steady state transfer of heat through a material with low thermal conductivity. Thermal conductivity is a measure of the material’s ability to transfer heat. This test happens in a closed system that measures the heat flow through the test specimen by using a hot plate on one side and a cold plate on the other. The device is calibrated before each test by using materials that have a known thermal conductivity and are similar to the test material in thickness. Once calibrated, the system can be used to measure flat materials in a wide range of thicknesses and conductivities. When the thermal conductivity and resistivity of a material has been established, it can then be used to determine energy losses through a material as well as satisfy R-value regulation for insulation material.

Service Temperature Testing
ASTM C447 – Practice for Estimating the Maximum Use Temperature of Thermal Insulations

This test method is based upon selected performance criteria and product properties during and after use conditions. Maximum use temperature depends on thickness, temperature gradient, heating rate, compressive strength, and dimensional stability, among other factors. The insulation is first subjected to the maximum anticipated use temperature. If there is significant deterioration of the properties tested during or after exposure at the maximum temperature, additional specimens will be exposed at lower temperatures to help establish a new maximum. This test method is especially important when it comes to insulating pipes at high operating temperatures. The insulation must be able to withstand these temperatures in order to keep processing parameters as constant as possible, and the insulation must be able reduce the heat flow as much as possible to the exterior interface for safety concerns when working with hot systems.

While these tests are all required to confirm that a material meets certain code requirements, there are other tests that JM has specifically pursued to confirm that fiberglass is safe for manufacturers, fabricators, and building occupants. There are three main areas of inquiry surrounding the impact of fiberglass on human health: 1) inhalation studies in animals to determine how lung tissue responds to various types of fibers (insulation fiberglass, special purpose fibers (SPF)), 2) human epidemiology studies of fiberglass manufacturing plant workers to determine if those workers have rates of respiratory disease higher than the general population, and 3) studies to determine the fiberglass exposure levels in occupational and commercial environments. 

Animal Inhalation Studies (in vivo studies):

Thein vivoinhalation studies were performed on rats and hamsters, and were done to better understand the mechanisms of respiratory disease, including cancer. Fiberglass and SPF fibers were the materials being studied, while asbestos fibers, a known carcinogen, were used as the control. These studies determined that each of these fibers have different levels of biosolubility (ability to dissolve in the lung). Insulation glass fibers were found to be more biosoluble, and the test animals were able to withstand exposure to fiberglass without any proliferation of tumors. SPF proved to be less biosoluble in the test animals and resulted in some fibrosis and tumors.  The conclusion from the studies was that fiber durabilityin vivois a critical indicator of disease hazard.

Human Epidemiology

This study explored the cause of death for individuals who worked in fiberglass manufacturing facilities. It accounted for nearly 1 million person-years of fiberglass exposure in manufacturing plants from 1945-1992. The studies revealed that there was no statistically significant increased rate of respiratory system cancers in this population when compared to the general population.

Occupational Exposure to Fiberglass

This is an on-going study performed by NAIMA, and is an initiative to determine exposure levels to inhalable glass fibers for both commercial and occupational applications. The database established has over 16,400 data points as of 2018. In terms of commercial exposure (exposure in buildings where fiberglass has been used to insulate the building and duct systems) the study found that, of the small amount of respirable fibers, the majority of fibers were organic in nature, meaning they came from carpets, drapes, etc.  The total fiber count per cubic centimeter was actually quite low, approximately 0.008 fibers per cubic centimeter. By comparison the inorganic fibers, like fiberglass, were less than .0001 fibers per cubic centimeter, and they were only present in 2 of 205 samples.

The occupational exposure database explores exposure in settings where workers are manufacturing and working with fiberglass: manufacturing; fabrication; installation; retrofit; and, removal. Findings indicate that the exposure is also low, well less than the 1 fiber/cc, the OSHA-NAIMA voluntary permissible exposure limit.

Unlike many other insulations, fiberglass has been thoroughly tested to determine its impact on respiratory system health. While it has been known to cause temporary mechanical irritation, fiberglass has b een confirmed to have no negative impact on lung tissue.

For detailed information about each of these fiberglass health studies, we encourage you to attend our upcoming webinar, “The Science Behind the Health and Safety of Fiber Glass and Mineral Wool,” on March 25th at 2:00pm ET/ 11:00am PT hosted by Bruce Ray, Johns Manville’s Associate General Counsel for Regulatory & Governmental Affairs and Kim Melton, Assoc. Content Marketing Manager and Technical Writer.