Does Your Attic Ceiling Need Insulation?

Types of Insulation

• There are several basic types of insulation that have different insulating properties. Batt insulation comes in a rolled blanket that is laid between your ceiling joists. Loose insulation is a mass of individual pieces of insulation that are blown, sprayed or poured into place. Reflective insulation consists of thin metal sheeting that lays above your existing insulation to reflect heat from the roof. Correctly installed loose or batt style insulation will improve the energy efficiency of homes during hot and cold seasons whereas reflective insulation is most effective at reflecting heat for homes in hot climates.

Recommended Amounts

• The thickness of the insulation in your ceiling is one of the key factors impacting its effectiveness. The San Diego Gas and Electric company recommends insulation with a total R-value of at least 30 in most climates. The R-value is a relative measure of the effectiveness of insulating materials. Batt insulation made of fiberglass typically has an R-value between 3.2 and 3.5 for each inch of thickness. Loose-fill fiberglass insulation provides R-values between 2.2 and 2.5 per inch, and loose fill insulation made of cellulose has an average R-value of 3.7 per inch. If your insulation measures less than ten inches thick, adding more insulation could provide substantial energy savings.

Sealing Gaps

• Increasing your insulation to meet the recommended amounts will only provide a marginal benefit if there are gaps in your insulation. Plugging these gaps will prevent heat from moving in or out of your home. Some common areas where gaps occur are near the eaves of your roof and around electrical conduits or air ducts. Spray foam insulation is cost effective for sealing gaps of several inches or less. Sealing gaps will reduce airflow between the outside and the interior of your home and increase the efficiency of your heating and cooling system.

Considerations

• Maintaining room for ventilation in your ceiling will help cool your home during the summer and reduce the accumulation of moisture during the winter. Reflective insulation in your ceiling is only effective if there is open space above it for heat to dissipate into. Insulation installed under the eaves of your roof should have a minimum of two to three inches of space above it. If your existing insulation is not thick enough, you can bolster it with an additional layer of insulation. Layer lighter insulation above your existing installation to avoid compressing it.