Adding attic insulation is probably the best bang-for-buck energy improvement most homeowners can make. I finally tackled mine last year and already noticed the difference in my heating bills.
Why It Matters
Heat rises. An underinsulated attic is basically a hole in your home’s thermal envelope. In winter, your heated air escapes upward. In summer, your hot attic radiates heat down into your living space. Either way, your HVAC system works overtime.
R-Value Basics
Insulation is rated by R-value – higher numbers mean better resistance to heat flow. The Department of Energy recommends R-38 to R-60 for most attics, depending on your climate. Up north, more is better. Down south, R-30 might suffice.
Check what you already have. Many older homes have R-11 or R-19. Adding more on top is usually the most cost-effective approach.
The Main Options
Fiberglass batts: The pink or yellow stuff in pre-cut strips. Easy to install between exposed joists. Cheap. Doesn’t fill gaps perfectly, though, so effectiveness varies.
Blown-in fiberglass: Loose fill that gets blown in with a machine. Fills irregular spaces better than batts. Home improvement stores often rent the blower free when you buy their insulation.
Cellulose: Recycled paper treated with fire retardant. Blown in like fiberglass but settles denser. Good environmental choice and effective performance.
Spray foam: The premium option. Creates both insulation and air barrier in one. Open-cell is cheaper; closed-cell has higher R-value per inch. Requires professional installation.
Before You Start
Air sealing comes first. Plug gaps around light fixtures, plumbing penetrations, the attic hatch – anywhere air can leak through the ceiling. Sealing air leaks dramatically improves how well any insulation performs.
Don’t block soffit vents. Attics need airflow to prevent moisture problems. Install baffles to keep insulation from covering the vents.
What I Did
I added blown-in cellulose over existing batts, bringing my total to about R-49. Did the air sealing first with caulk and spray foam. Total cost was around $800 for a 1,500 square foot attic. My heating bill dropped noticeably the first winter.
