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How to Install Blown-In Cellulose Insulation

Cellulose insulation is considered a "green" product — more ecologically sound than competing products. It's also highly effective and less costly than fiberglass. Learn how to install it with these easy steps.

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  • Time

    Day

  • Price Range

    $250 - $500

  • Difficulty

    Easy to Moderate

Highlights:

Step 1: Prepare the Attic

Place a plywood walkway down for easy and safe access in the attic (Image 1).

Determine coverage requirements by measuring length and width of your attic space. Determining the square footage of the attic will help you order the necessary amount of cellulose. To simplify measuring in a large attic, take each measurement in two steps. Slide a measuring tape to one side of the attic (eliminating the need to crawl all the way to the edge), and make a mark near the center point on the floor. Then slide the tape to the opposite side, measure out to the mark and add the measurements together. Once you have accurate length and width measurements, multiply the two numbers together to determine the square footage.

To keep the attic access free, and avoid blowing cellulose on top of it, place cardboard blocking around the access (Image 2).

Step 2: Protect Fixtures and Vents

With any type of insulation, it's important to keep the insulation material away from recessed lighting fixtures (Image 1). Use 10" flashing to block off recessed fixtures (Image 2), maintaining at least 3" of air space between the fixture and the flashing.

Also install metal flashing around heating fixtures, chimney flues (Image 3) and any other fixtures that generate heat.

Soffit-vent chutes (Image 4) prevent soffit vents from being covered with cellulose, helping to maintain good air circulation in the attic. Use a stapler to install the chutes over the soffit vents.

Step 3: Choose and Purchase the Cellulose

To help determine cost when ordering cellulose, bags of cellulose have charts listing amounts of material needed — according to specific coverage areas and desired R-values. If you know the coverage area in square feet, and the R-value you'd like to achieve, you can determine the cost by following the chart.

Once the amounts have been calculated and the cellulose purchased, work can begin on the process of blowing the material into the attic space with the specialized blower.

Step 4: Install the Cellulose

As the cellulose is blown in (Image 1), use a tape measure to gauge thickness.

Work away from the farthest corner of the attic, back to the attic access. This way, you won't need to walk through the cellulose once the job is done.

Cellulose is blown in around soffit chutes, but the structure of the chute prevents the cellulose from blocking the soffit vents. Blow the cellulose right around the chute (Image 2) to get full coverage at the edge of the attic.

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