Serving eastern Canada's wall and ceiling industry

By: Randy Straight

Since the introduction of fibreglass insulation in 1938, it has remained the prominent insulation material for commercial and residential construction. Over the years, fibreglass insulation has proven its ability to make buildings more energy-efficient, reduce utility costs, and increase occupant comfort. These and other important attributes have given it a new life as the leading insulation material in many of today’s green building projects.

Typically manufactured in two different forms — pre-cut batts and rolls, and blownin loose-fill insulation — fibreglass building insulation is used primarily for thermal and acoustical purposes in wall cavities, attics, and other critical open spaces in building assemblies. One of its key advantages is value. Fibreglass insulation has a lower installed price than many other types of insulating materials, and for equivalent R-value performance (i.e. thermal resistance), it is generally the most costeffective option when compared to cellulose or sprayed foam insulation systems.

Now, let’s take a closer look at the thermal performance of fibreglass building insulation.

Fibreglass insulation helps make buildings more thermally efficient by better retaining the desired temperature of enclosed spaces, whether they are heated or cooled. This reduces utility costs for building owners, conserves non-renewable fuel sources, and provides greater occupant comfort, when used in conjunction with appropriately sized heating and cooling equipment.

Additionally, fibreglass insulation offers design flexibility, as more of it can be installed in some sections of a building to increase overall thermal performance and compensate for areas with lower thermal values, such as windows and doors. It enables a wide range of R-values, giving the specifier more options for meeting provincial and national energy code requirements.

Fibreglass batt insulation products come in pre-made R-values, ranging from R-8 to R-40, whereas loose-fill fibreglass can be blown-in with pneumatic devices to meet almost any R-value requirement. Blown-in fibreglass insulation also can be installed over existing batt insulation in renovation projects to increase overall R-value.

Since it is inert and does not settle, properly installed fibreglass insulation maintains its R-value over a long period of time. Fibreglass insulation batts must always be installed at their full designed thickness to achieve the stated R-value — compressed fibreglass batt insulation loses R-value. For example, R-20 (RSI-3.5) fibreglass insulation with a thickness of 159 mm (6 1/4 in.) compressed to 140 mm (5 1/2 in.) will experience a reduction in R-value to R-19 (RSI-3.34). If the material is allowed to regain its original thickness, however, the full R-value is restored. Installers should always ensure the insulation completely fills construction cavities without gaps or voids.

When exposed to moisture, fibreglass insulation neither absorbs nor holds water. If fibreglass insulation does get wet during or after installation, installers should visually inspect it on all six sides for contamination. If the material appears free of visible defects, installers must dry it thoroughly to restore its full R-value. Once the area surrounding the insulation has also been inspected, cleaned, and fully dried, the fibreglass insulation can be reinstalled and it will regain its original R-value¹.

Made from sand and recycled glass, fibreglass insulation is naturally noncombustible and remains so for the product’s life. It requires no additional fire-retardant chemical treatments. Many building codes also recognize fibreglass insulation as an acceptable fire stop in wood and steelframed wall assemblies.

Fibreglass insulation is a naturally soundabsorbent material, which significantly reduces sound transmission in wall, ceiling, floor, and HVAC assemblies. The first inch of fibreglass insulation in a building cavity can increase an assembly’s sound transmission class (STC) value by three or four points in some constructions. Each additional inch can further increase the STC rating by two points².

Between 1992 and 2000, the fibreglass insulation manufacturing industry recycled more than 3.6 billion kg (8 billion lb) of pre- and post-consumer glass containers, eliminating the need for millions of cubic metres of landfill space³. Fibreglass insulation has significant recycled content, with some batt and loose-fill insulation products containing up to 80 per cent recycled glass⁴. The other main ingredient in fibreglass insulation – silica sand – is an abundant, naturally renewing resource, limiting environmental impact in its manufacturing process.

Many green building programs (i.e. LEED and Green Globes) grant additional credits for materials that are regionally manufactured and use locally sourced raw ingredients. CertainTeed has fibreglass plants strategically located across North America that allow building designers or specifiers to taken advantage of this important credit.

Fibreglass insulation packs multiple green performance features into one product and still comes at a very competitive price, when compared to other insulation materials. After 70 years on the market, it’s an excellent choice with a tried-and-true track record. RS

Notes

¹ Refer to NAIMA’s “FAQs About Fiber Glass Insulation.”

² See NAIMA’s publication # B1405, Sound Control for Commercial and Residential Buildings.

³ Refer to NAIMA’s “Insulation Facts #35: Comparing Fiber Glass and Cellulose Insulation.”

⁴ See Appendix A7 of The Environmentally Responsible Construction and Renovation Handbook, by Public Works and Government Services of Canada (PWGSC).