Quick Answer
Proper densification is crucial when blowing in cellulose insulation to ensure a tight, even fill and prevent gaps that can compromise its effectiveness.
Densification Requirements
Proper densification involves blowing in cellulose insulation to a density of 3.5-4 pounds per cubic foot (pcf). This density range is specified by the International Energy Conservation Code (IECC) and the National Appliance Energy Conservation Act (NAECA). Blowing in cellulose at this density range helps to achieve a tight fill, reducing air leakage and heat transfer.
Common Densification Mistakes
One common mistake when blowing in cellulose is not using the correct blower setup or not adjusting the blower for the specific application. Using the wrong blower setup can result in inconsistent density and a higher risk of creating gaps in the insulation. It’s essential to adjust the blower to achieve a consistent flow rate of 1-2 cubic feet per minute (cfm) per square foot of attic space. This flow rate helps to maintain the recommended 3.5-4 pcf density.
Achieving a Tight Fill
To achieve a tight fill, it’s essential to use a high-quality cellulose insulation product and follow the manufacturer’s instructions for blowing in the insulation. Start by blowing in cellulose in small sections, working from one end of the attic space to the other. Use a “sweeping” motion to fill the rafters and ensure a consistent fill. Use a thermal imaging camera or a blower door test to verify that the insulation is properly densified and there are no gaps or areas of low density.
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