VENTILATE AND INSULATE THE ATTIC
An attic is often the first place to insulate. An uninsulated or poorly insulated attic robs your home of heat in the winter and stores heat in the summer, making the top floor hotter and air conditioners work harder. Adding attic insulation is easy, and the amount of energy saved generally pays for the insulation in only a few years. Most importantly, comfort levels increase while fuel bills go down as a result of the insulation. Start by inspecting your attic. If no insulation exists, and you want to do the job yourself, measure the length and width of the attic. If you plan to use rolls or batts, you need to figure out the square footage. If you plan to use loose fill insulation, you need to calculate the cubic footage (number of square feet multiplied by the desired thickness of the insulation you plan to use). With these figures, you can determine the quantity of insulation needed and the cost. If insulation already exists, find out what kind it is, measure its depth, and calculate its R-value using the Types of Insulation table. Figure how much additional insulation you will need to approach a high R-value. If the attic has less than adequate insulation, it is worth adding more; if it has more than R-19, it is probably not worth adding more. You can mix and match insulation types (e.g. rock wool with cellulose or fiberglass). For exposed attics, pour-in cellulose or fiberglass, or fiberglass rolls and batts are easy to install as a do-it-yourselfer job. Enclosed or hard to reach areas may require professional installation by a contractor who will probably blow in loose cellulose or fiberglass. New installations require a vapor barrier on the living space side of the insulation. Use either 4 or 6 mil polyethylene sheets taped together at the seams, or rolls or batts with an attached aluminum vapor barrier. If you’re installing additional insulation, do not add a vapor barrier. If existing insulation lacks a vapor barrier, paint the ceiling below with vapor barrier paint or with two coats of oil based paint. To prevent a fire, keep all insulation 3 inches away from heat and light fixtures.
Insulated attics must be vented to protect the insulation and the roof. Moisture and heat build up in attics; installing attic vents provides a way for this heat and moisture to escape. Without venting, moisture would build up in the winter. Insulated wooden support members are prone to rotting from moisture in the summer. Venting provides an outlet for hot air, keeps a house cooler, and helps prevent asphalt roofing from degrading. Many different types of vents exist. Their use depends on the style and type of construction of your home, and cost. Place half of the vents high in the attic and the other half low in the attic for maximum results. Keep vents unobstructed and free of insulation so that air can flow through easily. It is important to have the right amount of ventilation. If the attic has a good vapor barrier, install one square foot of open vent area for every 300 square feet of attic area. If the attic lacks a vapor barrier, install one square foot of open vent for every 150 square feet of floor area. If the vent area is screened, it is not considered “open.” In this case, double the amount of vent area created by the screen material.