How to Insulate an Attic With Blown-in Insulation


A properly insulated attic reduces energy costs by reducing the flow of air into and out of the top of a house. Well-insulated houses stay warmer in winter and require less output from heating systems. Blown insulation is well-suited to insulating attics, with their sloping roofs and hard-to-reach spaces. Blown insulation achieves different R-values (the ability to resist heat flow) by varying the thickness of the layer; thicker layers have higher R-values. And most manufacturers provide recommended R-values based on geographic region; colder regions require more insulation and higher R-values. Installing blown installation isn't difficult.

Things You'll Need

  • Tape measure
  • Insulation blower
  • Flashing tubes
  • 2-by-12s


  • Make a walkway the length of the attic by laying 2-by-12s end to end across the ceiling joists. Place flashing tubes near any recessed light fixtures and heat-generating features, such as chimney flues and exhaust fans.

  • Block off any recessed light fixtures with metal flashing; leave at least 3 inches between the fixture and flashing. Install flashing around any heat-generating feature, again leaving at least 3 inches.

  • Measure the attic with a tape measure and multiply the attic's length by its width to determine square footage. Use the square footage to determine the amount of cellulose (insulation) needed.


  • Pour insulation into the blower. Have a helper keep the machine full to keep the insulation flow smooth and even. Climb into the attic and go to the far end; blow from the far end back to avoid contact with the insulation.

  • Hold the hose parallel and close to the floor with insulation falling 10 to 12 inches away. Blow right and left. Avoid blowing insulation in fixture blockers.

  • Measure the thickness depth with the tape measure. Add insulation as necessary.

Tips & Warnings

  • Blow insulation early in the day; attics get hotter as the day progresses.
  • Wear goggles, mask, gloves and protective clothing; insulation is an irritant.

Related Searches


Promoted By Zergnet



You May Also Like

Related Searches

Check It Out

22 DIY Ways to Update Your Home on a Small Budget

Is DIY in your DNA? Become part of our maker community.
Submit Your Work!