When insulating your home, you can choose from many types of insulation. To choose the best type of insulation, you should first determine the following:
Blanket insulation — the most common and widely available type of insulation — comes in the form of batts or rolls. It consists of flexible fibers, most commonly fiberglass. You also can find batts and rolls made from mineral (rock and slag) wool, plastic fibers, and natural fibers, such as cotton and sheep’s wool. Learn more about these insulation materials.
Batts and rolls are available in widths suited to standard spacing of wall studs, attic trusses or rafters, and floor joists: 2 inch x 4 inch walls can hold R-13 or R-15 batts; 2 inch x 6 inch walls can use R-19 or R-21 products. Continuous rolls can be hand-cut and trimmed to fit. They are available with or without facings. Manufacturers often attach a facing (such as kraft paper, foil-kraft paper, or vinyl) to act as a vapor barrier and/or air barrier. Batts with a special flame-resistant facing are available in various widths for basement walls and other places where the insulation will be left exposed. A facing also helps facilitate fastening during installation.
Foam boards — rigid panels of insulation — can be used to insulate almost any part of your home, from the roof down to the foundation. They are very effective in exterior wall sheathing, interior sheathing for basement walls, and special applications such as attic hatches. They provide good thermal resistance (up to 2 times greater than most other insulating materials of the same thickness), and reduce heat conduction through structural elements, like wood and steel studs. The most common types of materials used in making foam board include polystyrene, polyisocyanurate (polyiso), and polyurethane.
Loose-fill insulation consists of small particles of fiber, foam, or other materials. These small particles form an insulation material that can conform to any space without disturbing structures or finishes. This ability to conform makes loose-fill insulation well suited for retrofits and locations where it would be difficult to install other types of insulation.
The most common types of materials used for loose-fill insulation include cellulose, fiberglass, and mineral (rock or slag) wool. All of these materials are produced using recycled waste materials. Cellulose is primarily made from recycled newsprint. Most fiberglass products contain 40% to 60% recycled glass. Mineral wool is usually produced from 75% post-industrial recycled content.
Unlike most common insulation systems, which resist conductive and sometimes convective heat flow, radiant barriers and reflective insulation work by reflecting radiant heat. Radiant barriers are installed in homes — usually in attics — primarily to reduce summer heat gain, which helps lower cooling costs. Reflective insulation incorporates radiant barriers — typically highly reflective aluminum foils — into insulation systems that can include a variety of backings, such as kraft paper, plastic film, polyethylene bubbles, or cardboard, as well as thermal insulation materials.
Radiant heat travels in a straight line away from any surface and heats anything solid that absorbs its energy. When the sun heats a roof, it’s primarily the sun’s radiant energy that makes the roof hot. A large portion of this heat travels by conduction through the roofing materials to the attic side of the roof. The hot roof material then radiates its gained heat energy onto the cooler attic surfaces, including the air ducts and the attic floor. A radiant barrier reduces the radiant heat transfer from the underside of the roof to the other surfaces in the attic. To be effective, it must face an air space.
Radiant barriers are more effective in hot climates, especially when cooling air ducts are located in the attic. Some studies show that radiant barriers can lower cooling costs 5% to 10% when used in a warm, sunny climate. The reduced heat gain may even allow for a smaller air conditioning system. In cool climates, however, it’s usually more cost-effective to install more thermal insulation.
Rigid fiber or fibrous board insulation consists of either fiberglass or mineral wool material and is primarily used for insulating air ducts in homes. It is also used when there’s a need for insulation that can withstand high temperatures. These products come in a range of thicknesses from 1 inch to 2.5 inches.
Installation in air ducts is usually done by HVAC contractors, who fabricate the insulation at their shops or at job sites. On exterior duct surfaces, they can install the insulation by impaling it on weld pins and securing with speed clips or washers. They can also use special weld pins with integral-cupped head washers. Unfaced boards can then be finished with reinforced insulating cement, canvas, or weatherproof mastic. Faced boards can be installed in the same way, and the joints between boards sealed with pressure-sensitive tape or glass fabric and mastic.
Liquid foam insulation materials can be sprayed, foamed-in-place, injected, or poured. Foam-in-place insulation can be blown into walls, on attic surfaces, or under floors to insulate and reduce air leakage. Some installations can yield a higher R-value than traditional batt insulation for the same thickness, and can fill even the smallest cavities, creating an effective air barrier. You can use the small pressurized cans of foam-in-place insulation to reduce air leakage in holes and cracks, such as window and door frames, and electrical and plumbing penetrations.
Today, most foam materials use foaming agents that don’t use chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which are harmful to the earth’s ozone layer.
There are two types of foam-in-place insulation: closed-cell and open-cell. Both are typically made with polyurethane. With closed-cell foam, the high-density cells are closed and filled with a gas that helps the foam expand to fill the spaces around it. Open-cell foam cells are not as dense and are filled with air, which gives the insulation a spongy texture.
The type of insulation you should choose depends on how you will use it and on your budget. While closed-cell foam has a greater R-value and provides stronger resistance against moisture and air leakage, the material is also much denser and is more expensive to install. Open-cell foam is lighter and less expensive but should not be used below ground level where it could absorb water. Consult a professional insulation installer to decide what type of insulation is best for you.
Available foam insulation materials include:
Some less common types include Icynene foam and Tripolymer foam. Icynene foam can be either sprayed or injected, which makes it the most versatile. It also has good resistance to both air and water intrusion. Tripolymer foam—a water-soluble foam—is injected into wall cavities. It has excellent resistance to fire and air intrusion.
Reposted from Energy.gov