Let’s face it. When it comes to home renovation and construction, insulation is not the most glamorous topic. The thought typically conjures images of itchy, pink fiberglass, and is an area of home improvement that most homeowners leave to the experts. “I believe most people would rather have a professional put in insulation and let someone else get itchy,” says Frank Douglas, production manager at Quality Insulation in Nashua, N.H.

Yet it is possible to undertake an insulation project and witness substantial energy savings from it. According to statistics from the U.S. Department of Energy, 50 to 70 percent of the energy used in the average home comes from heating and cooling. By ensuring that your home is adequately insulated, you can help maintain a uniform temperature year round and reduce your heating bill. The key to achieving these savings is in understanding the basics of insulation including the types available and their various uses.

Types of Insulation

Fiberglass and Rock Wool. Like most people, you are probably familiar with fiberglass insulation, especially in its batt or roll form. “Fiberglass is your most common form of insulation, usually installed in conjunction with a vapor barrier,” says Todd Thompson, project manager at Trumbull-Nelson Construction Co. in Hanover, N.H. A vapor barrier keeps moisture from reaching cold surfaces where it can condense.

Fiberglass, like rock wool, is a mineral insulation made from recycled glass, molten sand or rock. It is lightweight, and the type of insulation that you are thinking of when you picture the itchy, pink stuff, although it comes in yellow or white as well.

By ensuring that your home is adequately insulated, you can help maintain a uniform temperature year round and reduce your heating bill.

Fiberglass and rock wool insulation are available in both blankets, such as batts or rolls, and loose-fill or blown-in forms. Fiberglass batts come in precut packages of 48 inches or 93 inches in length and are designed to accommodate standard wall stud and joist spacing. Common batt thicknesses are 3-, 5- and 6-inches. Faced batts feature kraft paper or aluminum foil on one side that serves as a vapor barrier. You can also purchase fiberglass in rolls up to 70 feet in length.

The popularity of fiberglass insulation stems from its flexible, versatile and inexpensive nature, making it an excel-lent choice for do-it-yourselfers. Fiberglass blankets are ideal for new home construction and unfinished walls, floors and ceilings. Both rock wool and fiberglass insulation come in a loose-fill form that requires special equipment to blow in or spray apply it to enclosed building cavities, attics and difficult to reach areas. Although loose-fill is typically used for remodeling projects, you can also blow it into new, open wall cavities. Unlike batts, which go in between ceiling joists, blown-in insulation “covers the structure,” says Douglas. “It is also cheaper in most applications such as an attic, for example.”

If you wish to upgrade your insulation, Douglas says “we can put a mesh on the exterior wall, which acts as a support for the insulation, and blow in a fine, high-end, fiberglass insulation that is close to double the cost of a regular fiberglass batt.”

Cellulose and Polyurethane Foam. Cellulose insulation is recycled and fire-treated newspaper that you can either blow into enclosed, existing wall cavities or open, new wall cavities and unfinished attic spaces. Because it consists of organic material like newspaper, cellulose insulation is treated with a chemical, such as borax, to make it fire resistant.

“Cellulose is often installed over the top of ceilings and is used in renovating buildings without tearing the siding or finish off,” says Thompson. “You can cut holes in the building and blow the cavities full of insulation.”

“Cellulose is cheaper than fiberglass, especially in older homes where we’ve pulled the siding off, drilled through the sheeting and blown it in,” says Douglas. “It also travels better than fiberglass when it gets in a tight area around an electrical box and pipes — it breaks up finer and travels better.”

Spray foam insulation, usually made from polyurethane, is also applicable in retrofit and new construction projects. “It combines both vapor barrier and insulation properties, helping to reduce air leaks,” says Thompson. “It is very popular nowadays.”

Rigid Insulation. Rigid insulation, such as blue board, is made from plastic foams like polystyrene and polyurethane. Rigid insulation is frequently used on basement walls and exterior walls with weatherproof facing.

Reflective Insulation. Reflective insulation consists of aluminum foil-faced paper, film or cardboard that you can fit between roof rafters, floor joists and wall studs.

R-Value

Since heat moves from warm to cool spaces, all insulation is rated on its resistance to heat flow. This rating is called an R-value — the higher the R-value, the more effective the insulation.

If you are adding new insulation to a previous layer, you can determine the total R-value by adding the layers together. The density of the insulation also plays a role in its R-value. Denser material yields a higher R-value. Thickness, however, does not necessarily dictate a product’s density. For houses built with 2 x 4s, Douglas recommends using fiberglass insulation with a R-value of R-11, R-13 or R-15. “In attic areas use R-30 or R-38,” he says.

Areas to Insulate

The most common areas to insulate in the home are the attic, exterior walls and floors, the basement and crawl spaces. In most cases, the nature of the project and the space you are dealing with will determine the type of insulation you need. For example, as Thompson noted, loose-fill is convenient to use in closed and finished areas since all you (or a professional) need do is cut small holes in the wall and blow in the insulation, rather than ripping up significant portions of the building. Once the expert fills the cavities, he may use small pieces of wood to plug the holes and replace the siding.

You may prefer loose-fill for attic applications as well since it more thoroughly covers the ceiling joists and reduces heat loss through the wooden frame. If you choose to use fiberglass batts instead, you may tackle this problem by crisscrossing the batts over the existing insulation, creating “a thermal bridge” that also helps slow the transfer of heat. Do-it-yourselfers frequently insulate basement and crawlspace walls with rigid insulation or fiberglass batts.

Before undertaking any insulation project, you should seal air leaks around such common areas as switch boxes, windows, chimneys, trap doors and pipes. You can seal holes in electrical boxes with caulk or foam while unfaced rock wool or fiberglass works around chimneys. You should also consider weatherstripping trap doors and windows and tightly placing insulation in gaps around pipes.