Properly insulating the attic can help to keep your property warm and also reduce the cost of heating bills. The attic is one of the easiest places in the house to insulate, but effective insulation depends on properly sealing all air leaks between the attic and the rest of the property. The amount of insulation material required for attic installation depends on where you live and how much insulation is already in the attic.
Attic insulation material is graded by "R-value" that measures the material's heat resistance. Insulation materials with a higher "R-value" provide more thermal efficiency than those with lower values. The R-value requirement depends on your local climate and whether you're adding to existing insulation or installing insulation in a new property. For example, an uninsulated attic in Florida requires R-30 to R-60 insulation whereas an uninsulated attic in Minnesota needs insulation of at least R-49 to R-60. Check on local requirements at a home improvement center or by contacting the U.S. Department of Energy.
Proper preparation is the key to effective insulation. For attic insulation to work properly, seal up all air leaks between the attic and the rest of the property. Use furnace cement or high-temperature caulk to seal around chimneys and apply long-life caulk to seal small holes and gaps around the tops of interior walls. Foam boards or strips can seal larger gaps effectively. The attic must have ventilation, so install duct exhaust fans from inside to outside the attic. Cover the fan housing inside the attic with a box and seal the duct where it exits the box. Cover all openings to the attic area, such as bulkheads and soffits, with plywood to prevent air leaks.
Fire safety is a major consideration when installing insulation in attics. Once you've sealed the attic for air leaks and installed the necessary ventilation duct, make sure that any heat-producing equipment in the attic, for example, exhaust fans, lights and chimneys meets fire safety clearance requirements. This means at least a 3-inch gap between the heat-producing equipment and surrounding insulation. If necessary, create the necessary clearance by installing metal flashing blocking around the heat-producing equipment or structures.
The most common types of attic insulation are loose-fill or batt insulation. In loose-fill installations, the insulation material is spread loosely over the the attic. Batt insulation comes in rolls. Unroll the insulation batts and push each batt into place between the wooden joists in the attic roof frame. Loose-fill insulation is usually less expensive to install and provides better coverage, according to the United States Department of Energy.
If you want to add to the insulation already in your attic then exercise caution. Some older insulation materials consist of vermiculite that might contain asbestos. Asbestos poses a severe health risk, so don't attempt to remove it yourself. Always get an insulation contractor that is certified to handle asbestos to remove any vermiculite insulation materials.