The Best Insulation for Your Attic

The right attic insulation depends on your home, your budget, and what you're trying to fix. A drafty older attic with lots of gaps has different needs than a sealed new build. So instead of one winner, it helps to understand where each material shines.

The three you'll most often choose between are fiberglass, cellulose, and spray foam — each with a clear set of strengths.

Fiberglass comes as batts or blown-in loose fill and is the most common choice for good reason: it's affordable, non-combustible, and performs reliably. Blown-in fiberglass is especially good at filling odd-shaped spaces and covering an attic floor evenly.

It's a strong default for most homes, particularly in a mild climate where extreme R-values aren't necessary.

Cellulose is made largely from recycled paper and is treated for fire and pest resistance. It's denser than fiberglass, which gives it good coverage and decent sound dampening, and it's a favorite for homeowners who want a more eco-friendly option.

Because it's dense, it does an excellent job filling gaps in an existing attic floor when blown in over the top of older insulation.

Spray foam is the premium option. It insulates and air-seals in one step, reaching a high R-value per inch and sealing gaps that other materials can't. That makes it powerful for attics with lots of air leakage or tricky geometry.

It costs more and should be professionally installed, so it's usually reserved for situations where its air-sealing strength is worth the investment. A professional can help you weigh whether foam or a fiberglass/cellulose upgrade fits your goals and budget best.