Blown in Insulation Cost: Average Prices & Cost Factors

Blown-in insulation, also called loose-fill, is shot into an attic or wall cavity through a hose. It fills gaps and odd shapes that rolled batts miss, which makes it a common choice for topping up attic insulation in an existing home.

The price depends on the material, the area, and whether you hire a crew or rent a machine and do it yourself. The figures below show per-square-foot costs and one worked example.

A typical attic job shows how the numbers work together. The area is multiplied by the per-square-foot rate, and the installer's minimum charge, setup, and any prep work come on top.

DIY cuts the labor, but the material price is roughly half the professional cost in the table, so what you save is the labor and equipment charge.

Blown-in insulation comes in several materials.

• Cellulose. Made mostly from recycled paper treated for fire and pest resistance. It is dense, settles slightly over time, and is a common choice for attics.
• Fiberglass. Lightweight and widely available. It does not absorb moisture the way paper-based products can, but it can let air move through more readily.
• Mineral wool. Made from rock or slag. It resists fire and moisture well and is less common in residential attic work.

Each material has a different R-value per inch, which is the measure of resistance to heat flow. A higher R-value means better insulation. Your installer can tell you how many inches of each material are needed to reach a target number.

The right R-value depends on your climate zone and the part of the house being insulated. The U.S. Department of Energy publishes a recommended range by region at energy.gov. Compare that target with what you have now. If you can see the tops of the joists in your attic, you likely have room to add more.

Hiring a pro means a crew with a blower truck, a measured depth, and a finished job in a day or less for many homes. Doing it yourself means renting a machine, buying bags, and working in a hot attic with a respirator, goggles, and protective clothing. A pro is the better choice if you have wiring in the way, recessed lights, or an unclear moisture problem.

DIY is realistic in an open, unfinished attic with good access. Keep in mind that uneven depth leaves cold spots, and blocked vents make the attic hold moisture.

Preparation affects performance as much as the material does. Before any insulation goes in:

• Seal air leaks around wiring holes, plumbing stacks, and the attic hatch. Insulation slows heat flow but does not stop air.
• Install baffles at the eaves so insulation does not block soffit vents.
• Keep insulation clear of recessed lights unless they are rated for contact.
• Fix roof leaks or moisture first. Wet insulation loses much of its value.
• Mark the depth in several spots so you can confirm even coverage.

• Area. A larger attic costs more overall but less per square foot on many jobs.
• Material. Cellulose, fiberglass, and mineral wool are priced differently.
• Depth. A higher target R-value needs more material.
• Access and obstacles. Cramped attics, ductwork, and wiring slow the crew.
• Prep. Air sealing and baffles are often billed separately.
• Removal. If old, damaged, or contaminated insulation has to come out first, the job costs more.
• Location. Labor rates vary by region.

Batts are pre-cut rolls or panels. They suit open, regularly spaced cavities and are easy for DIYers. Blown-in material works better around obstructions and irregular spaces, and it is the usual way to add to existing attic insulation. Wall retrofits in finished homes generally use blown-in or dense-pack methods because they do not require tearing out drywall.

• Which material will you use, and what R-value will the finished depth reach?
• Does the quote include air sealing, baffles, and cleanup?
• How is the final depth verified?
• Is there a minimum job charge?
• Is there any rebate or tax credit available for the work?

Your electric or gas utility, and the federal energy efficiency programs, may offer incentives for insulation upgrades, so ask before you sign.