Types of Attic Insulation Explained

Batts are pre-cut panels — usually fiberglass — designed to fit snugly between standard joist and stud spacing. They're inexpensive, widely available, and straightforward to install in open, regularly spaced attics.

Their weakness is gaps. Around obstructions, wiring, and irregular framing, batts leave spaces that reduce overall performance unless they're carefully cut and fitted.

Blown-in insulation — loose fiberglass or cellulose — is machine-blown into the attic, where it settles into an even blanket that fills gaps batts can't. It's excellent for covering an existing attic floor and reaching tight corners.

It's the go-to for adding insulation to an existing attic because it layers easily over what's already there and conforms to the space.

Spray foam expands on contact to fill and seal every gap, insulating and air-sealing in a single step. It reaches a high R-value per inch and is unmatched at stopping air leakage.

It's the most expensive option and requires professional installation, so it's typically chosen when its air-sealing power solves a specific problem — like a leaky, hard-to-seal attic.

Many homes end up with a combination — blown-in over the floor for coverage, with air sealing to close the gaps. The best choice depends on your attic's layout, your budget, and whether air leakage is a major issue.

A professional inspection takes the guesswork out of it, matching the material to your attic and your goals.