Loose-fill insulation is typically made from small particles of fiberglass, cellulose, or mineral wool, which can easily conform to any space without disrupting the structure or fixtures. This type of insulation is applied using a specialized blowing machine, making it ideal for attics with irregular joist spacing, numerous obstructions, or existing insulation that needs to be supplemented. 

It’s particularly effective for attics with low clearance where maneuverability is limited. Loose-fill insulation is commonly used in open-blow applications for attic spaces, while closed-cavity applications are suited for inside walls or covering attic floors. Some settling of the insulation may occur over time.