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Insulation has come a long way since its earliest know applications, in which Egyptians used mud and straw to keep the desert heat out of their homes. Nevertheless, people are still highly dependent on these cost-saving and comfort-inducing construction materials. The only difference is that there are now dozens of different kinds of weatherization materials.
We’ve got the rundown on all of the most common types of residential insulation. It is important to note that insulation new and old contain toxic chemicals and materials. Exposure to these substances can pose some very serious health risks.
Before we explore the different types of residential insulation, let’s talk about how insulation materials are categorized.
Insulation Categories
The EPA has established a system for categorizing common residential insulation materials. Each material is given an R-value, or thermal resistance value. This rating system is used to determine how much heat a material can trap beneath. The EPA uses these ratings to determine the effectiveness of particular insulation materials in various residential and commercial settings.
R-values are also used to help homeowners determine which insulation materials are suitable for distinct climates, types of heating and cool system, and placements.
The United States is divided into eight different insulation zones. The lowest zones include places with tropical climates. For example, Zone 1 covers Hawaii, Guam, Puerto Rico, and the Virgin Islands. Meanwhile, Zone 8 consists of several areas within Alaska.
In Zone 1, uninsulated attics require insulation materials with R-values range from 30 to 49. Meanwhile, unfinished attics in Zone 5 require insulation materials with an R-value between 49 and 60.
Blanket Insulation: Batts and Rolls
Blanket insulation is one of the most readily available and widely used types of residential insulation.
It is available in batts and rolls of varying thicknesses. The sheets, which are sold in different sizes and can be cut to fit virtually any space, are made up of small fibers. Meanwhile, batts, which are also made of compact fibers, are designed to fit snugly between conventionally placed rafters, joists, and studs.
The fibers are typically made from fiberglass, though there are also mineral wool (rock and slag), plastic, and natural varieties.
Blanket insulation is typically installed against unfinished walls and floors, such as those in crawl spaces, attics, and foundations. The panels are usually positioned between studs, joists, and beams.
Both blankets and panels are sold with and without reflective foil facings. Foil-faced batts are typically used when insulation is being applied on top of preexisting insulation.
Blanket insulation is easy to install and relatively inexpensive. However, rodents have been known to chew through and even burrow in this material. The heat generated by blanket insulation is enough to make a crawlspace or attic a welcome site for rats and mice.
Fiberglass
Fiberglass, or glass wool, is an insulating material made of loosely matted glass fibers. Fiberglass batting is by far the most popular type of insulation for exterior walls in commercial and residential buildings. It is used to stop the spread of heat and cold.
The R-rating of fiberglass batting varies depending on its thickness. According to the EPA, 3 ½ inch thick fiberglass batt has an R-value of 11. Meanwhile, a 6 to 6 1/4 inch thick fiberglass batt has an R-value of 19. Generally speaking, thicker batt insulation has a higher price per square foot.
Unfortunately, rodents tend to nest inside fiberglass insulation. It is very arduous to remove damaged fiberglass insulation, as it is made from fine glass fibers. The fibers are easily embedded in the skin or inhaled.
Mineral Wool (Rock and Slag)
Mineral wool batt insulation is made from densely packed molten glass, stone, and slag (industrial waste) fibers. The materials are usually fused by some sort of chemical binder and oil. Mineral wool is one of the most efficient insulators on the market. It has an R-value of 3.7 to 4.2 per square inch.
Mineral wool tends to cost roughly 25% more than fiberglass batt insulation of the same size. Mineral wool is water-, mold-, mildew, and fire-resistant. It also protects against the unwanted invasion of sound. However, it can be a major hassle to install and remove. This type of insulation tends to shed tiny fibers. The fibers are easily embedded in the skin and inhaled, which is a major problem since they are known to cause cancer.
Plastic Fibers
Plastic fiber blanket insulation consists of loosely matted panels made of recycled plastic fibers. These fibers are typically made from recycled milk bottles (polyethylene terephthalate or PET).
Unfortunately, rodents don’t mind tunneling or nesting in this type of insulation. The removal of infested plastic batt insulation is messy and dangerous. Those that are responsible for removing rodent- or mold-infested plastic batt insulation must protect themselves against airborne diseases and contaminants.
Natural Fibers
Some homeowners have made the switch to more expensive and eco-friendly natural fiber batt insulation. Sheep’s wool batt insulation has an R-value of 3.5 to 3.8 per square inch. Since sheep’s wool can absorb a lot of moisture, it does an excellent job of cutting down on humidity. However, it also tends to attract rodents that use its fine, crimped fibers to build nests.
Concrete Block Insulation
Some homeowners use foam-filled concrete blocks to raise the R-value of their walls. Concrete block insulation comes with different R-values. For example, an 8-inch concrete wall with expanded polyurethane filler has an R-value of 12.5. Meanwhile, an 8-inch wall that is made of insulation-filled cinder blocks has an R-value of approximately 4.85.
Foam Board
Rigid foam board insulation, or wall sheathing, is available in varying thicknesses ranging from 1/4 to 2 inches. These panels can be used to insulate many areas in the home, including attics, basements, slab foundations, and exterior walls. They are usually placed up against plywood or some other sort of structurally reinforcing material.
While rigid foam board insulation is popular with consumers, it is not 100% impervious to pests. There have been instances where mice and rats have managed to chew through rigid foam insulation.
Polystyrene
Expanded polystyrene, or plastic foam, is one of the most common types of rigid foam board insulation. Polystyrene is a type of hard, bubble-filled plastic. It does a phenomenal job of keeping buildings warm. It has an R-value of 5.
Many homeowners choose expanded polystyrene to insulate their homes. It can be used above and below grade. It resists moisture and mold. Foil-backed expanded polystyrene has an even higher R-value. However, it can only be used above ground.
Polyurethane
According to the EPA, polyurethane foam board insulation is often used to weatherize unfinished walls, floors, ceilings, and unvented low-slope roofs. Rigid polyurethane is popular because it has a high thermal resistance value, and it is relatively thin. This closed-cell insulation has an R-value of 3.4 to 6.7 per inch of thickness.
It is also important to note that spray-polyurethane foam insulation is toxic. It can cause several health issues, including asthma and lung irritation if it is absorbed through the skin or inhaled. Homeowners must take extreme care when handling this and other polyurethane foam products.
Polyisocyanurate
Polyisocyanurate is a closed-cell, rigid foam board insulation that is used on walls, roofs, and ceilings. It has a high R-value. Moreover, it does not absorb water or vapors easily. Unfortunately, like other foam insulation materials, polyisocyanurate is highly susceptible to rodents.
Loose and Blown-In Fill
Loose and blown-in insulation is typically used to fill hard-to-reach areas, including attics and crawlspaces. It is sometimes used to fill the gaps left by other sorts of insulation materials. It comes as rigid foam panels or loose particles. Blown-in insulation is sprayed into place with the assistance of a special hose system.
The most common types of loose and blow-in insulation materials include cellulose, fiberglass, and mineral insulation. These materials are remarkably efficient insulators for the hard-to-access and irregularly shaped areas behind walls, ceilings, and floors.
Cellulose
Cellulose insulation consists of loose chemical-treated plant fibers. It is typically made of recycled newspaper. Chemically treated newspapers. It can be blown into walls and roof cavities to keep the heat in and cold air out. The R-value of cellulose ranges from 3.2 to 3.8. People often wonder if rodents are attracted to cellulose. However, mice and rats tend to avoid this variety of insulation because it typically falls apart too easily. You’ll typically find this sort of insulation in attics.
Fiberglass
While fiberglass batts are more common, this type of insulation can also be blown into crawlspaces and eves. Blown-in fiberglass consists of chopped up glass fibers. Its R-value ranges from 2.2 to 4.2.
Mineral (rock or slag) wool
Blown mineral wool is used in both residential and commercial building applications. It consists of chopped up rock and slag fibers. It has an R-value of 3.1 to 4.0.
Urea-Formaldehyde Foam
Urea-formaldehyde foam is yet another obsolete variety of residential insulation. It is a compressed foam that was once shot behind the walls and eves of homes. Urea-Formaldehyde Foam is a registered carcinogen. Researchers have found that mice who were regularly exposed to urea-formaldehyde foam developed cancer cells. Homeowners should avoid disturbing this potentially harmful material.
Asbestos
Asbestos is yet another dangerous yet antiquated type of residential and commercial insulation. While asbestos has been banned since the 1980s, it still found in many older homes throughout the United States. This type of insulation is linked to a long list of health concerns, including mesothelioma, asbestosis, and lung cancer. Homeowners should never attempt to handle asbestos. People must take extreme precautions to avoid exposure to this toxic material.
Loose-Fill (Poured) Polystyrene Beads, Vermiculite, and Perlite
Polystyrene beads, vermiculite, perlite are also used to insulate residential structures. These sorts of insulations take the form of smooth, lightweight pellets. They are not the most common types of loose-fill insulation materials. They typically have lower R-values than other types of insulation. For example, the R-value of loose-fill perlite is just 2.7 per inch.
Loose vermiculite and perlite insulation are typically found in older homes, particularly those built before 1950. Some older perlite and vermiculite installations have been found to contain asbestos. Therefore, you must never attempt to remove or even disturb this type of insulation.
Unfortunately, rodents have been known to tunnel through these materials.
Reflective and Radiant Systems
Reflective and radiant barriers are a little different than traditional insulation. Most radiant or reflective barriers consist of highly reflective materials adhered to durable substrates, such as kraft paper, cardboard, or rigid foam.
Homeowners in warm climates typically install these types of panels between the joists and rafters in their attics and crawlspaces to keep heat out. Meanwhile, people in cold, temperate zones use foil-faced batt insulation to keep their homes and businesses toasty during the wintertime.
Foil-Faced Kraft Paper
Foil-faced kraft paper is a type of radiant insulation that is sometimes installed against attic walls, roofs, and walls. Foil-faced kraft paper creates an effective vapor barrier over fiberglass and other blanket insulation.
Unfortunately, when foil-faced kraft paper is installed incorrectly, rodent droppings and moisture often accumulates underneath the insulation. Foil-faced kraft paper should never be exposed. It must always be installed so that it is flush with the ceiling, floor, or wall materials.
Plastic Film
Some homeowners use plastic film to insulate their windows during the winter. Plastic film can help a home retain 55% of its heat.
Polyethylene Bubbles
Sheets of reflective polyethylene bubbles are sometimes placed up against exterior and interior walls to trap heat and protect against moisture damage. Polyethylene bubbles are often used as vapor barriers. They are a favorite among cautious homeowners, as they resist fungus, mildew, and rodents. However, since the R-value of polyethylene bubbles tends to be very low, these sheets are typically only used in mild climate zones.
Cardboard
Some homeowners choose to utilize radiant cardboard panels. Foil-faced cardboard insulation is economical and easy to install. However, it is subject to moisture, humidity, fire, rodent, and mold damage. The R-value of cardboard is somewhere between 3 and 4.
Spray Foam
Blown-in polyurethane foam (SPF) is sprayed into the cavities inside walls, floors, and ceilings. Spray foam grows until is 30 to 60% bigger than it was in its original liquid form. There are high-density closed-cell and low-density open-cell spray foams.
Spray foam has a high thermal resistance value (R-value), and it is relatively inexpensive. Plus, it is one of the only types of insulation that is not easily damaged by rodents.
How Rodents Threaten Attic Insulation
When rodent infestations occur inside attics and crawl spaces, contaminated insulation must be removed and properly disposed of before sanitation and restoration can take place.
Rodent, including rats, mice, squirrels, and raccoons, are known to infest the generally off-limits areas, including and especially areas with insulation. When they do, these materials become contaminated with rodent droppings, urine, nests, and remains. They then have the potential to harbor harmful pathogens, including bacteria and viruses.
When a home or business is infested with rodents, a professional rodent dropping remediation company may be hired to clean, sanitize, and dispose of contaminated insulation. They will come prepared with the necessary personal protective equipment and cleaning apparatuses.
Removing rodent-infested insulation takes patience and skill. Workers must utilize specialized equipment and don appropriate protective equipment. Attics, crawlspaces, and other areas that contain insulation tend to be very compact. What’s more, these areas usually lack adequate ventilation. Moreover, cleaners must comply with strict local and federal insulation disposal regulations.
Remember, if you want to keep rodents out of your insulation, you need to block them from entering your home altogether. If you are faced with the task of removing this hazardous material, consider calling a professional.
Evaluating Insulation
You can optimize the performance of your insulation by making sure it is installed correctly. One way to button up your weatherization materials is to have them air-sealed. You can also check the EPA’s weatherization guide to be sure you are using an appropriate type of insulation. Insulation can be used in attics, ducts, ceilings, exterior walls, floors, basements, crawlspaces, foundations.
