Types of insulation
Batts are flexible products made from mineral fibers, including fiberglass or rock wool. Batts are available in widths suited to standard spacing of wall studs. When installing batts, make sure the batts fill the entire wall cavity, and that there are no gaps or squishes which would decrease the batt’s effectiveness. The batts must be hand-cut and trimmed to fit wherever the joist spacing is non-standard (such as near windows, doors, or corners), or where there are obstructions in the walls (such as wires, electrical outlet boxes, or pipes).
Blown-in loose-fill insulation
Blown-in loose-fill insulation includes cellulose, fiberglass, or rock wool in the form of loose fibers or fiber pellets that are blown using equipment, usually by professional installers. This form of insulation is typically installed in unfinished attic floors. Cellulose is made from recycled newspapers and is treated with a fire retardant.
In the open wall cavities of a new or exposed wall, cellulose and fiberglass fibers can also be sprayed after mixing the fibers with an adhesive or foam to make them resistant to settling.
Polyicynene is an open-celled foam. Polyisocyanurate and polyurethane are closed-cell foams. In general, open-celled foam allows water vapor to move through the material more easily than closed-cell foam. However, open-celled foams usually have a lower R-value compared to closed-cell foams. Some of the closed-cell foams are able to provide a greater R-value where space is limited such as attic rooflines.
A professional uses special equipment to meter, mix, and spray the foam into place
Rigid insulation is made from fibrous materials or plastic foams and is produced in board-like forms and molded pipe coverings. This rigid insulation provides a greater R-value where space is limited. Rigid insulation is often used for foundations and as an insulating wall sheathing. Rigid insulation should also be installed on vertical and sloped walls in the attic.
Reflective insulation, also called a radiant barrier, is a metallic foil material (usually aluminum) designed to block radiant heat transfer across open spaces. Reflective insulation helps reduce cooling bills in hot, sunny climates. However, in some cases (special installations) the product can help reduce heating bills as well. Keep in mind, the effective R-value of the product will vary depending on the direction of heat flow (up, down, sideways). The product’s performance and long-term cost depends on a number of factors, including where the product is installed, how the product is installed, and the amount of existing insulation currently in the home.
Source: Department of Energy – Insulation Fact Sheet
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