The attic in your home contributes more to its energy efficiency than any other place under the roof, making adequate attic insulation a must-have for keeping heating and cooling costs under control. The roof has around-the-clock exposure to the weather, and heat is constantly entering or leaving from the roof’s surface. Bringing the insulation up to recommended levels slows this thermal transfer, translating to lower HVAC bills.
Benefits of Attic Insulation
Because heat constantly seeks cooler temperatures, improving the attic’s ability to resist temperature change lowers energy costs. The U.S. Department of Energy (DOE) reports that half or more of the average household’s annual energy costs go toward keeping the home comfortably warm or cool. More insulation reduces those costs.
Another benefit is a quieter indoor environment. Sound waves won’t penetrate through the ceilings as easily, and if you live in a noisy neighborhood, increasing the insulation will block some of the sound transmission.
Insulation Choices
Most homes in the Houston area have fiberglass batt or loose cellulose inside the attic. Both work effectively to slow heat transfer. The DOE estimates that 10 to 20 inches of these types of attic insulation provide an adequate buffer for heat transfer. However, since summers are so hot in the Houston area, it’s better to go with a higher R-value for fiberglass products than the DOE recommends.
Recent studies have shown that fiberglass products lose some of their insulating capabilities as the attic temperature rises. The Building Science Corporation studied the ability of fiberglass batts to resist heat transfer as temperatures rose. They found that fiberglass batt with an R-13 rating lost R-value as temperatures climbed. The R-value fell to 11 when attic temperatures rose over 140 degrees. Unless your attic has good ventilation, it can approach this temperature on a hot, sunny summer day.
If your home’s attic doesn’t have enough room for these levels of insulation, you can opt for other products that have higher R-values. All insulation products are rated by their ability to resist heat transfer, and the number following the “R” indicates how many hours it resists temperature change. Ten inches of fiberglass or cellulose insulation have R-values of 30, giving you 30 hours of protection.
Foam products have higher R-values per inch of thickness than cellulose or fiberglass whose R-values are 3 per inch. Sprayed closed cell foam has the highest R-value at 6.2 per inch. Rigid foam sheets have R-values that range from 4 to 6.5 per inch.
Doing the Job
Some homeowners opt to install the attic insulation themselves, since it’s widely available at home improvement centers. Blown-in insulation requires a special blower that most home centers rent for a small charge. However, if your attic has any of these characteristics, you may want to have a professional contractor take on the project:
- Bare, exposed wires in the attic
- Cramped space
- Limited fresh air ventilation built into the attic
- Dryer and ventilation fan vents that exit inside the attic, not through the roof
- Moldy insulation or wood rot in the attic or roof
- Dusty areas that indicate loose ductwork for the HVAC system
Each of these issues needs to be addressed by a professional, especially wiring, mold, ductwork leaks and poor ventilation.
Installation and Creating Barriers
If you opt to install the insulation yourself, read the product’s instructions carefully. Be sure you wear all the protective gear the manufacturer recommends because these products can irritate the skin, respiratory system and eyes.
When installing more fiberglass batts over existing batts, lay them perpendicular to the old ones to create a better barrier. Don’t compress the existing or new batts, since the R-value for this type of insulation will go down when it loses some of its loft by squeezing it into tight spots.
You may encounter recessed lighting fixtures that protrude into the attic. Check to see that they’re insulation contact (IC) rated if you want to cover them. If they’re not, create sheet metal or wire mesh barriers to keep the insulation off them. The mesh should be fine enough to prevent any loose fiberglass or cellulose attic insulation from sifting through and landing on the wires.
For assistance with evaluating your need for attic insulation and trimming your energy bills, contact ACS Absolute Comfort. We’ve provided exceptional HVAC services for Houston area homeowners since 2007.
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