There are several options for insulation in new homes. Some of these materials have specific features that make them more efficient in some applications.
Fiberglass is one of the most commonly used insulation materials. It is available as blanket (batts), loose-fill, and rigid boards.
Structural Insulated Panels (SIPs) use foam board or liquid foam injected under great pressure between wood skins to create an extremely dense structure that insulates better than conventional walls.
Fiberglass
Fiberglass is one of the most common insulation materials for building construction. It’s made from tiny glass fibers that are spun at high temperatures. They are then packed together into rolls that builders call batts. These are easy to cut to size and place in wall and attic cavities.
These insulation products can be paper-faced, foil-faced or unfaced, and are usually treated with a fire retardant. They provide thermal and acoustical insulation with R-Values from R-11 to R-38.
This is the most economical insulation option, and it’s also one of the most commonly used in new homes. It is moisture resistant, so it will not promote the growth of mold or fungus. However, it does attract pests that burrow, nest and defecate in the material. In addition, it is a skin and respiratory irritant.
Mineral Wool
Mineral wool is a green alternative to fiberglass and offers higher R-values in a smaller volume of material. It prevents convection by entrapping air in its open-cell, woolly matrix. Its low thermal conductivity prevents heat transfer and it resists fire spread better than fiberglass insulation materials.
It also withstands moisture better than other insulation materials. Fiberglass and cellulose will droop or clump up if they become wet, but mineral wool batts maintain their shape. It also doesn’t provide food for microorganisms like mold and mildew.
In addition to high R-values, mineral wool is a great sound-control option. It reduces noise transmission by creating a sound barrier, and it doesn’t lose its R-value over time. It also offers a natural resistance to fire, flame and smoke, making it an ideal choice for homes with an SFHA certification or those who want to build to the passive house standard.
Reflective Insulation
Reflective insulation works by reflecting heat back, rather than trapping air as bulk insulation materials do. It can be used on its own up north in places with warm weather to reduce radiant transfer, but is usually combined with bulk insulation like ‘INSUshield’ or cellulose to also slow down convection and conduction transfer and improve the R-value of the overall assembly.
Unlike foam board insulation that can require a strong vapor retarder to be effective, reflective insulation does not interfere with vapor movement and can reduce condensation problems in wall and roof cavities. These characteristics make it a popular choice for crawl spaces and basic floor heat retention applications as well as metal buildings, post frame and pole barns.
It is free from the flammable chemicals and volatile organic compounds (VOCs) that can be released by foam board insulation during installation, making it safer to handle. It is also naturally fire-resistant, which can be an important consideration in locations with strict building codes and fire safety regulations.
Cellulose
Cellulose insulation is a blown-in product that can be either loose-fill or densely packed. Professionals install cellulose insulation by drilling holes in the walls or attic, inserting a filler tube, and blowing the material into the wall cavities or attic. Typically, the cellulose is mixed with fire retardants and other additives.
Studies have shown that cellulose insulation performs well. It fits well around pipes and wires, and it seals air leaks better than fiberglass insulation. It also limits convection by its density, which is good news for energy efficiency.
As a recycled product, cellulose is a great option for environmentally-conscious homeowners. It is made from recycled paper, which reduces the need for raw materials and energy to make new insulation. Greenfiber cellulose insulation, for example, is manufactured without unhealthy formaldehyde and meets California’s stringent standards for low VOC emissions.
Spray Foam
Spray foam insulation is a unique insulation material that creates both an air seal and a thermal insulator. It’s often used in homes and commercial buildings. It is usually spray-applied, but can also be poured. Foam insulation has a high R-value, meaning it resists thermal heat transfer very well.
It seals nooks and crannies that are common in wood-frame construction, preventing the air leakage that can drive up energy bills. This type of insulation is especially effective for wood-frame homes, where the gaps and voids left by electrical wiring and plumbing can be a significant source of air infiltration.
There are two types of spray foam insulation: open and closed cell. Both offer the same benefits, but each has its own specifics. Closed-cell spray foam has a higher R-value and provides stronger resistance to moisture, but it is more expensive than open cell. Both should be applied by a professional, and both can be found in two-component kits.
Foam Beads
Foam bead insulation is made from polystyrene molecules and is puffed up using a steam process to become EPS or XPS foam blocks. They are durable, lightweight, and have great moisture resistance. They can be moulded to fit many different applications and have excellent thermal properties.
It is a good choice for retrofitting existing walls as it can be installed in less than a day. However, it can be a messy job as it tends to stick to anything that touches it. This loose-fill insulation is not recommended for use in New Zealand due to its reaction with electrical cables that generate heat and require sheathing.
It is important to remember that, when properly installed and air sealed, all insulation types perform equally well. The goal is to get the highest R-value for your money in the products you choose. Maximizing your R-value is also critical for energy efficiency.