Blown-In vs. Batt Insulation

Batt insulation comes in pre-cut rolls you lay between joists, while blown-in insulation is loose material machine-blown into place. Both are commonly fiberglass, but they behave very differently once they're in your attic.

The right choice usually comes down to your attic's layout and whether you're insulating from scratch or adding to what's there.

Blown-in insulation wins on coverage. It settles into an even layer that fills around wiring, pipes, and irregular framing, leaving few gaps. That seamless coverage often translates to better real-world performance.

Batts can perform well in a clean, evenly spaced attic, but every obstruction is an opportunity for a gap. Poorly fitted batts leave spaces that quietly undercut their rated R-value.

Batts are inexpensive and DIY-friendly in a simple attic, which keeps material costs low. Blown-in requires a blowing machine and is usually professionally installed, but it goes in quickly and covers large areas fast.

For adding insulation over an existing layer, blown-in is typically the easier and more effective route, since it layers cleanly on top without the fuss of fitting batts around what's already there.

If you're topping up an existing attic or dealing with lots of obstructions, blown-in is usually the better performer. For a simple, open attic on a tight budget, batts can do the job.

When in doubt, a professional can assess your attic and recommend the approach that gives you the best coverage for your money.