This winter, as in past winters, many clients have asked whether better attic insulation would help them stay warmer and reduce their energy bills. The answer, of course, is yes! But there’s a giant caveat.
If you’re going to beef up your attic insulation, you need to seal the air leaks first.
Otherwise, you’re spending a lot of time (and possibly a lot of money) on something that will only provide marginal improvements. More insulation alone is helpful, but it’s monumentally helpful when combined with air sealing.
That’s true for your attic and your crawlspace, by the way.
Where insulation helps you the most
Before going over why air sealing is so important, it’s important to understand where insulation makes the biggest impact. If your home was built sometime in the last 40 years, you probably have insulation in your attic, walls, and possibly your crawlspace (we’ll assume you have one).
Due to the stack effect and the reverse stack effect, heat tends to migrate vertically through buildings. As such, the insulation above and below you has the biggest impact on your home’s thermal performance.
In other words, attic and crawlspace insulation is the most important insulation.
If you’re going to add insulation to your home, you should focus on the attic and crawlspace. Only worry about your wall insulation after you’ve optimized the insulation above your ceiling and below your floor.
Note: Typically, an insulated crawlspace will have fiberglass batt insulation installed between the floor joists. Over time, this insulation often falls to the ground, reducing its effectiveness to zero. If you have this problem or are concerned about it, crawlspace encapsulation is the solution.
Which brings us to attics…
…and crawlspaces, for that matter. Let’s say you were really cold this winter, spent a lot on natural gas, and want your home to be more comfortable and efficient next winter. You’ve decided to add insulation to your attic and crawlspace, which is good! You’re certainly on the right track.
But insulation only blocks heat. It doesn’t block air.
More insulation will improve your home’s thermal performance by keeping more heat inside your home in January. However, insulation is not an air barrier. Warm air inside your home can still weasel its way through the little gaps and cracks around electrical, plumbing, and HVAC penetrations in your attic and crawlspace.
That air is carrying a lot of the heat that you’re paying to produce and keep inside your home. Even with more insulation, you lose a lot of heat through these air gaps.
So before you replace or add insulation, seal the leaks.
In attics, the solution to inadequate insulation is usually to blow new loose fill fiberglass or cellulose material on top of the existing insulation, whether batts or otherwise. Before we add this insulation, we always move or lift the old stuff, and use canned foam or zero-VOC silicone to seal air leaks around ducts, ceiling fans and light fixtures, wires, pipes, and exhaust fans.
Sometimes, the air gaps are really big! Air sealing before you add insulation can result in significant comfort and efficiency improvements, especially in leaky older homes.
We do the same thing in crawlspaces. Before adding insulation between the floor joists, we air-seal all the penetrations between the crawlspace and the floor. Of course, a fully encapsulated crawlspace is the best option for below-the-floor thermal performance, but air sealing under your floor joist batts still provides noticeable improvements.
Did we mention it helps during the summer?
Remember: insulation and air sealing also prevent heat and humidity from getting into your home when it’s hot outside!
These improvements work both ways. In winter, they block heat and warm air from leaving your home. In summer, they block heat and warm air from entering your home. Quality thermal upgrades do offer year-round benefits!
Air sealing + insulation = a complete home performance upgrade
By itself, more insulation is good. Ditto for air sealing.
But doing both at the same time is the absolute best solution for improving your home’s thermal performance 24/7/365.
If you live in Metro Atlanta and are thinking about insulation or air sealing improvements, get in touch with us! We’ll analyze your existing insulation, take some measurements, and point you to the best possible improvements for your home!