Home improvement storescarry two major classes of insulation: fiberglass and rigid foam.
Both are designed for residential use.
For example, rigid foam is commonly used forbasement wallinsulation because it resists the moisture from basement masonry walls.
The Spruce / Jason Donnelly
Fiberglass batts are typically insulated between wall studs, floor and ceiling joists, and roof rafters.
In contrast to rigid foam, fiberglass is soft and flexible.
The batts' thicknesses range from 3 1/2 to 12 inches.
The Spruce / Michela Buttignol
Fiberglass insulation rolls or batts may be faced with paper to simplify attachment to framing members.
Unfaced batts or rolls are better for laying as an insulating blanket.
The thickness of the insulating material mostly determines the R-values of rigid foam and fiberglass.
The Spruce / Jason Donnelly
Rigid foam insulation packs more R-value per cubic inch than fiberglass insulation.
Rigid foam R-values range from R-1 for 1/4-inch thick sheathing panels to R-15 for 3-inch thick panels.
A comparable R-value for rigid foam costs roughly $10.
The Spruce / Jason Donnelly
Fiberglass insulation also produces less waste.
When rigid foam is cut to size, it produces small pieces and thin sections that are virtually unusable.
Ease of Installation
Both rigid foam and fiberglass have pros and conswhen it comes to installation.
Rigid foam’s main advantage is its clean, irritant-free product.
Fiberglass’s advantage is that it is flexible enough to mold around obstructions.
However, although it is more resistant than fiberglass, rigid foam is not fully waterproof.
It’s best to use higher-density rigid foam for homes in wet areas with more moisture.
Fiberglass insulation is not water resistant and is prone to getting wet, mold damage, or rot.
Insects and rodent pests may nest in the material, leaving behind fecal contamination.
Fiberglass insulation that gets water damage or pest contamination must be replaced.
Depending on the rigid foam, some types can off-gas volatile organic compounds (VOCs).
VOCs are most intense immediately after installation.
Fiberglass has tiny fibers that tend to aerosolize during installation and over time.
These small fibers affect air quality.
If pests begin nesting in the materials, their urine and feces will also affect air quality.
Lower-quality fiberglass materials contain additives like formaldehyde, which are considered VOCs that can affect human health.
Rigid foam has the highest R-value, is more durable, and is moisture-resistant.
It is often selected as the insulator of choice for basements.
Fiberglass is less expensive and easier to install.
U.S. Department of Energy.
Fiberglass.Washington State Department of Health.
Facts About Fiber Glass Insulation and Vapor Retarders.North American Insulation Manufacturers Association.
