Insulation is a vital aspect of home energy efficiency. But which type of insulation is best? It depends on your building design, climate, budget, and whether you are constructing or remodeling.
Fiberglass and cellulose are two of the most common types of insulation available. But each has perks and drawbacks.
Fiberglass
Fiberglass insulation consists of tiny glass fibers bundled together to create a soft, flexible material that can be blown or pressed into wall cavities, attics, and floors. It is inexpensive and does not settle over time, ensuring it will last. It’s also non-flammable, reducing the risk of fire.
Fiberglass can also be found in blanket batts and rolls, which are pre-cut to fit between wall studs. It can be installed easily by simply laying it between wall studs and taping it in place, or you can install a sheet of kraft paper as a vapor barrier before installing the fiberglass. These vapor barriers prevent condensation from forming in metal buildings, which reduces the risk of mold and mildew, as well as improves indoor air quality.
Foam insulation, ranging from expanded or extruded polystyrene (EPS or XPS) to closed-cell spray foam or polyurethane (PUR) or polyisocyanurate (PIR), offers high R-value per inch of thickness. It is very effective in small areas where other types of insulation may not work, such as around pipes and ductwork.
It is not as durable as fiberglass, but it does offer superior insulating qualities and helps to prevent air leakage. It is available in a wide variety of R-values to accommodate a range of needs, including R-3 for walls and R-6 for ceilings. It’s also a highly sustainable option since it’s made from recycled materials.
Cellulose
Cellulose insulation is made of recycled paper products such as old newspapers, phone books and cardboard. Manufacturers grind these materials up with a hammermill or mill and then treat them with boric acid and fire retardants to create cellulose insulation bales. The cellulose is then “blown-in” with special equipment to fill open attics and enclosed wall, floor and cathedral-roof framing cavities.
Blown cellulose is very dense and, unlike fiberglass, resists heat transfer (conduction). It’s also more effective than other traditional house insulation types at blocking air flow that causes drafts. However, it is not as effective at blocking sound transfer.
Besides its thermal and air infiltration resistance, blown cellulose has other benefits that make it a good choice for a wide range of building types. It provides a natural mold inhibitor and has strong soundproofing properties that help reduce noises from the outside, as well as noises between different levels of your home or building.
Because it’s made from recycled paper, cellulose is one of the most environmentally friendly insulation types available. Cellulose also has the lowest embodied energy of all commonly used insulation materials. It requires 20 to 40 times less energy to produce than furnace-made mineral insulation such as fiberglass. However, cellulose does require the use of borates, which are derived from non-renewable mined resources. Moreover, cellulose is hygroscopic and can absorb liquid water, which degrades its thermal performance.
2-Part Spray Foam
When insulating a home, the rooftop is an area that needs special consideration. Since heat or cold can escape through the roof, it’s critical that this area be properly insulated to ensure optimal energy efficiency. This is why the rooftop should always be a starting point when considering insulation options for a new home or retrofit project.
Spray polyurethane foam (SPF) is a type of insulation that is sprayed into place and expands to fill gaps, nooks, and crannies for a tight seal. This type of insulation can offer a variety of R-Values depending on the manufacturer and style.
Low-density spray foam has an R-Value that begins at R-3.6 per inch and is considered open-cell, while high-density spray foam has an R-Value of R-5.5 to R-7 per inch and is called closed-cell.
While both spray foam insulation options offer a great R-Value, they are not equal in their ability to prevent air leakage. In fact, open-cell spray foam is more susceptible to air leakage than high-density spray foam due to the air pockets it creates when it expands.
As a result, both open and closed-cell spray foam insulation should be installed by a professional and not a DIY homeowner. However, for do-it-yourselfers who want to save money and enjoy the satisfaction of a job well done, there are fiberglass and cellulose insulation products available that can be purchased at local hardware stores with specific installation instructions provided by the manufacturer.
Blanket Batts & Rolls
Blanket insulation is one of the most common types of insulation used in new construction. It’s made from flexible fibers and comes in both batts and rolls. It can be made from a variety of materials including fiberglass, mineral (rock and slag) wool, plastic fibers, and natural material like cotton or sheep’s wool. It’s also available in varying thicknesses and R-values.
Insulation batts are pre-cut segments of blanket insulation that come in 4 foot or 8 foot lengths. They are typically around 16 inches or 24 inches wide which matches the standard spacing between wall studs for wood framing. They are easy to install in a wall and can be cut to fit around wiring, pipes or other obstacles. It’s important to measure your space correctly when installing blanket insulation as it can lose its R-value if it’s not installed properly.
Rolls of blanket insulation are a bit more challenging to work with as they need to be cut down to size before installation. This can make them difficult to work with in a small space like an attic. They are also usually longer than insulation batts and may need to be trimmed down to the correct length when installing in an older home or in a building with unique stud and joist spacing.
Both rolled and batt blanket insulation is a good choice for new construction because it’s a cost effective solution that can help meet energy codes. It’s also available in a range of R-values to match the needs of each climate zone.