Batt vs. Blown-In Insulation

Batts are pre-cut blankets that fit between studs and joists. Blown-in is loose fill machine-blown over and around framing. For most retrofit attics, blown-in covers gaps better; for new-construction stud bays, batts can be faster.

Side-by-side specs

SpecBattBlown-In
Installation speed (attic)1–2 days DIY2–4 hours pro
Real-world R-value70–85% of label95–100% of label
Cost per sq ft$0.65–$2.00$1.00–$2.75
Best forNew construction, accessible stud baysRetrofit attics, topping off existing

Batt

Pros

  • Predictable R-value per pack
  • DIY-friendly for accessible walls
  • No machine rental needed
  • Easy to remove for future renovations

Cons

  • Leaves gaps around wires, plumbing, framing
  • R-value drops 30%+ if compressed or misaligned
  • Slow over irregular framing

Blown-In

Pros

  • Fills around all obstructions
  • Faster on attic floors
  • Higher achieved R-value in real installs
  • Better for adding on top of existing insulation

Cons

  • Requires a blower (rented or pro)
  • Can settle 10–20% in attics
  • Messy — needs containment
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Which should you pick?

  • Adding to existing attic insulation: Go with Blown-In. Blown-in conforms over what's already there.
  • Insulating an unfinished wall before drywall: Go with Batt. Batts are faster in clean, accessible stud bays.

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