Insulating Your Home: Understanding the Basics of Effective Insulation

A home insulation plan that takes air sealing and ventilation into account can dramatically improve a home's energy efficiency. This, in turn, can save on utility bills while also making the home more comfortable year-round. Here are three critical questions to consider to ensure effective home insulation.

What Type of Insulation Is Best for Your Home?

Insulation should be chosen based on the home's design and the local climate. The U.S. Department of Energy has guides to help builders or homeowners figure out the right insulation for each application.

Insulation is categorized by its resistance to conductive heat flow, which is known as its R-value. The higher an R-value, the more effective the insulation.

Insulation types can be generally broken down into three types: foam, fiber, and reflective insulation. Foam comes in a spray form or rigid sheets. Spray foams are especially effective at sealing out drafts. Sheet foam has higher R-values than fiber insulation but is more expensive.

Fiber insulation comes as either loose fill that is blown into wall or attic cavities or in sheets that are rolled out. Blown insulation, when properly installed, can provide more coverage than sheets or batts.

Reflective insulation works by reflecting radiant heat. Assessing this type's R-value can be difficult because its placement determines its effectiveness.

Where Should Insulation Be Installed?

At a minimum, insulation should be placed in the exterior walls, on the floor of an unfinished attic, and the walls between the garage and the indoor areas of the house. It can also sometimes be put over wall sheathing, the material placed between the exterior wall and any covering like stucco, brick, or siding. In some areas, local building codes require that foundations and building slabs be insulated, as well.

How Much Insulation Is Needed?

The answer to this question will generally come down to local building codes, the design of the house, the local climate, and what kind of insulation is used. However, older homes may not be insulated to today's standards.

In an underinsulated home, a homeowner can save around 10% of their energy bill by sealing air leaks and adding additional insulation. Several insulation choices can be added after construction to make a home better insulated.

The attic is one of the easiest places to add insulation in most homes. Loose fill can be added to the top of existing loose-fill insulation. In most places, 8–12 inches of fill is adequate.

Roll or batt insulation can be laid between or over ceiling joists or placed over existing loose fill. This type of insulation is widely available at building supply stores and is made from cotton, wool, or fiberglass.

Rigid foam panels can be added between roof rafters or laid over existing insulation on the attic floor. These can easily be cut to size to fit into available spaces.

It is possible to add insulation inside walls without removing drywall. Spray foam can be added by cutting holes in exterior siding. This foam expands when it makes contact with air and will fill all crevices to keep outside air from getting in.

Some insulation jobs need to be done by a professional, while handy homeowners easily accomplish others. Homeowners should check out their homes to see whether there are places where more insulation can be installed. By finding places allowing heat or air conditioning to escape to the outside, the homeowner can keep temperatures more consistent inside. This will reduce power consumption, save money, and make a far more comfortable home.