InsulationPal Logo
Back to DIY Guides

Attic Insulation: Step-by-Step How-To Guide

Comprehensive instructions for Blown-in, Loose-Fill, and Roll & Batt installations, including prep, safety, tools, and pro tips.

Before You Start

  • Wear PPE: gloves, long sleeves, eye protection, and a respirator or dust mask.
  • Seal air leaks around lights, pipes, and openings before insulating.
  • Check for moisture issues or roof leaks and resolve first.
  • Maintain clearances around recessed lights and flues per local code.
  • Install rulers/markers to verify final insulation depth for R-value.

Blown-in Attic Insulation

Best for achieving high R-values and filling irregular cavities. Typically uses cellulose or loose fiberglass with a rental blower.

  1. Measure attic area and determine target R-value by climate zone.
  2. Install depth markers across the attic indicating required finished depth.
  3. Air seal penetrations and install baffles at eaves to maintain ventilation.
  4. Position blower outside; run hose to the attic. One person feeds, one spreads.
  5. Start at the farthest corner and work back toward the hatch.
  6. Keep the hose low and level; move steadily for uniform coverage.
  7. Check marker depths frequently and add material to low spots.
  8. Build a dam around the attic hatch to contain loose insulation.

Loose-Fill (Manual) Installation

Suitable for small attics or touch-up work. Materials are spread manually without a blower.

  1. Calculate coverage based on bag labels and target R-value.
  2. Place depth stakes and install baffles at eaves for airflow.
  3. Open bags and gently loosen material by hand into even layers.
  4. Spread with a rake to avoid mounding; do not compress insulation.
  5. Verify depths across the attic, topping up low areas as needed.

Roll & Batt Installation

A common DIY method. Use faced batts with the vapor retarder toward the living space unless local code states otherwise.

  1. Measure joist spacing and select correct batt width and thickness.
  2. Cut batts with a straightedge on scrap plywood; avoid compressing.
  3. Lay batts snugly between joists; split around wiring and obstructions.
  4. Staple flanges to the side of joists (if faced) without over-tightening.
  5. Layer perpendicular batts if additional R-value is required.
  6. Maintain clearance from heat sources and recessed lights per code.

Pro Tips

  • Use walkway boards to avoid compressing insulation and for safety.
  • Mark truss bays completed to ensure even coverage.
  • Keep soffit vents clear with baffles to prevent moisture issues.

Get Started

Learn More

Insulation Articles

Expert guides and tips

What is Attic Insulation?

Learn about attic insulation