Cellulose vs.
Fiberglass Cost
Fiberglass often looks cheaper at first glance, but the better attic value depends on target depth, coverage quality, settling risk, and how the whole quote is scoped.
Cellulose and fiberglass are the two materials most homeowners compare for attic floors. The right call depends on more than material price per bag because each product behaves differently once it is installed across a real attic.
Where Fiberglass Usually Wins
- Lower raw material cost
- Common availability through many installers
- Good fit for simple top-offs where the main goal is more coverage
Where Cellulose Often Wins
- Higher R-value per inch than blown fiberglass
- Denser coverage around irregular framing
- Often a better fit when the attic needs more thermal performance in limited depth
Compare Cost by Final Result, Not Only by Material
The fair question is how much each option costs to reach a useful final attic condition. A colder attic in Zone 5 may need meaningfully more depth than a mixed-climate attic in Zone 3, which changes the comparison quickly.
What to Ask When Comparing Quotes
- What final depth or final R-value will each quote deliver?
- Is attic air sealing included before installation?
- Are baffles, dams, or hatch improvements part of the scope?
- How does the installer account for settling or final coverage?
Related Resources
View all guidesZoom out from material choice to full attic prep, access, and target depth.
Put cellulose and fiberglass in context with spray foam and other attic options.
Measure your attic first so you can compare quotes against the real gap.