Comparing Residential Insulation Types
When considering insulation for your project, it’s important to understand the facts about different product types and options. First thing’s first: there is no such thing as a “best insulator”. Surprised? According to the Building Sciences Corporation (BSC), all insulation types perform equally well when properly installed and air sealed.
Understanding Different Insulation Materials
There are four main types of insulation products on the market today used for attics and wall cavities: fiberglass, rock or slag wool, cellulose, and spray foam. Each of these options has different qualities and attributes that may inform your choice of materials. Additionally, Extruded Polystyrene (XPS), Expanded Polystyrene (EPS), Polyisocyanurate (PIR), and Polyurethane (PUR) Boards are common in both continuous sheathing and under slab applications. This section focuses on the former.
Fiberglass insulation: Made from glass cullet and other raw materials which are melted and spun into fibers that resemble the texture of wool. It comes in batts, rolls, or loose-fill forms and is commonly used in sidewalls, attics, floors, crawl spaces, cathedral ceilings, and basements.
Stone, rock, or slag wool insulation: Made from rock, blast furnace slag, and other raw materials which are melted and spun into fibers to resemble the texture of wool. Mineral wool comes in batts, rolls, or loose-fill forms. Like fiberglass, it is also used in sidewalls, attics, floors, crawl spaces, cathedral ceilings, and basements.
Stone and slag wool insulation are comprised of basically the same raw materials, are produced in the same ways, and produce fairly similar performance attributes. The major difference is in the specific volumes of the various raw materials used to make each product.
Cellulose insulation: Composed mostly of cellulose fibers usually derived from paper, paperboard stock, or wood, and made with or without binders. Cellulose is chemically treated to resist fire, but the application process isn’t standardized, and there is evidence that the fire resistance wears off over time.[i]
Spray foam insulation: Chemical-based insulation that is mixed on-site to create foam, and applied with a sprayer in attics and into wall cavities. The two main types of spray foam insulation are open cell and closed cell. The properties of each are somewhat different.
There are many factors that may influence the quality of spray foam products, including:
- The mixing process of the two chemicals on site
- The age of the chemicals: they have a shelf life that can affect mixing and application
- Air temperature and humidity during installation: if the relative humidity is too high or the air temperature too low, there can be problems with installation
- Temperature of chemical storage: optimal storage is between 18 and 30ºC (65 and 85ºF), depending on manufacturer guidance. If there are variances, or chemicals are mis-stored, the product can be compromised.
|Features||Fiberglass||Mineral Wool||Spray Foam||Cellulose|
|Thermal Performance R-value--Batts[ii]||2 x 4” wall (3.5”) R-12 to R-14[iii] 2 x 6” walls (3.5”) R-19 to R-24[ii]||2 x 4” wall (3.5”) R-12 to R-15[ii] 2 x 6” walls (3.5”) R-12 to R-24[ii]||2 x 4” wall (3.5”) N/A 2 x 6” walls (3.5”) N/A||2 x 4” wall (3.5”) R-13[ii] 2 x 6” walls (3.5”) N/A|
|Thermal Performance R-value—Blown-In||2 x 4” wall (3.5”) R-12 to R-14[ii] 2 x 6” walls (3.5”) R-19 to R-24[ii]||2 x 4” wall (3.5”) R-14.5[ii] 2 x 6” walls (3.5”) R-23[ii]||2 x 4” wall (3.5”) R-12 to R-22[iv] 2 x 6” walls (3.5”) R-19 to R-35||2 x 4” wall (3.5”) R-12 to R-13 2 x 6” walls (3.5”) R-19 to R-20|
|Air Sealing||Required to work properly||Required to work properly||Provides some air sealing if applied properly, but no insulation product has been proven to provide a continuous, whole-home air barrier. [v]||Required to work properly|
|Installation||Batts: option to DIY Blown-In: professional installation is recommended. The installer must use a machine capable of installing fibre glass or mineral wool. Some grades of mineral wool can be poured.||Batts: option to DIY Blown-In: professional installation is recommended. The installer must use a machine capable of installing fibre glass or mineral wool. Some grades of mineral wool can be poured.||Requires professional installation, and inhabitants are required to vacate the premises||Dry application: option to DIY Wet application: Requires professional installation with a blowing machine to add water|
|Settling||Batts: No settling Blown-In: Virtually no settling[vi]||Batts: No settling Blown-In: Virtually no settling[vi]||Shrinkage over time[vii]||Batts: N/A Blown-In (dry): Can settle up to 20% in attics[vi]|
|Health Impacts||Proven track record for safe use. 90% of product in residential market today is formaldehyde free. [viii]||Thoroughly tested product[ix]||A main ingredient in spray polyurethane foam insulation, methylene diphenyl diisocyanate, has inherent health risks[x]||Very limited health and safety testing|
|Recycled Content and Renewable Resources||Contains upwards of 70% recycled glass, and sand, a renewable and abundant resource||Slag wool contains 10-15% recycled content, and rock wool contains 70-90%. Both contain minerals like basalt or diabase and blast furnace slag, limestone, or dolomite||None||Contains 80% or more recycled content, including newspapers or wood fibre|
|Fire Safety||Naturally fire resistant, but faced insulation will contribute to flame spread unless flame-resistant materials are used[xii]. Can resist melting up to 1300ºF (704ºC).||Naturally fire resistant, and can resist melting up to 2,150ºF (1177ºC)||Can be consumed by flame and will ignite at 371ºC (700ºF)[xiii]. Exposed foam should be protected using a Class B thermal barrier, i.e., gypsum or some mineral fiber products.||Naturally flammable. Manufacturers must apply 20%, by weight, of fire retardants|