Q: When I add insulation to my attic, how do I ensure it’s done correctly?
A: Your attic is often the area you can get the most bang for your buck on energy-efficiency investments. Insulation is just one part of the energy-efficient attic puzzle.
Here are a few tips to keep in mind as you prepare to make your attic more efficient.
Step 1: Sealing
Warm air often leaks out of the attic in winter or into the home during summer. Trouble spots include anything that comes through the attic floor, such as recessed lights, the chimney, the attic hatch and pipes, and ducts or wires coming through the attic floor.
It is best to properly seal these trouble spots before adding or improving insulation. Invest a small amount of money in the necessary supplies—caulk, expanding foam or weatherstripping—to seal any air leaks in your attic.
Step 2: Ventilation
Many attics are under-ventilated, which lets moisture and heat build up. Moisture causes harmful mold and wood rot.
During summer, a poorly ventilated attic is prone to overheating, which can bake shingles and shorten their life. During winter, a warm attic can melt snow on the roof, causing it to run into your gutters and then freeze, causing ice dams.
Proper attic ventilation lets air flow from a low point to a high point. This is usually done by installing soffit vents and insulation baffles around the perimeter, plus vents near the peak of the roof. If there is no way to install enough attic ventilators, install an attic fan to provide mechanical assistance to exhausting overheated air.
Step 3: Insulation
The three main types of insulation for attics are loose-fill, batt and rigid. Whichever you choose, it must provide a high enough level of insulation for your region, measured in R-value.
Batt and rigid insulation often have the R-value printed on them. Loose-fill, which is blown in, is the most common for attic floors. Its R-value is approximately its depth in inches multiplied by 2.8.
Generally speaking, your attic should have 14 to 24 inches of loose-fill insulation if you live in a northern state, and 11 to 14 inches if you’re in a southern state. You can find the recommended level for your region at energy.gov.
If your loose-fill insulation is less than the recommended amount, it should be easy to add more on top of it—as long as there are no moisture, rodent, ant or termite problems.
If your existing loose-fill insulation was installed before 1990, it could be vermiculite, which may be contaminated with asbestos. Asbestos can cause cancer when particles are released into the air, so it’s a good idea to have the insulation tested. If it’s contaminated, have it removed by a professional before beginning work.
Seal and insulate attic walls that border conditioned space, such as skylight openings.
Some of these steps can be challenging, so consider hiring a professional. If you’re a do-it-yourself pro and decide to do some of the work on your own, be aware of potential hazards. Disturbing old wiring can cause shorts in your electrical system, and roofing nails will often pierce the attic ceiling. Another danger is stepping off the rafters.
Years ago, I (Pat) decided to do some work in my attic on a hot afternoon. The heat must have gotten to me, because I slipped and crashed through the attic floor. My daughters were quite surprised to see my legs dangling from the ceiling, with broken sheetrock and insulation everywhere. What a mess!
Always remember safety when tackling your projects.