There are several types and installation methods for insulation, from batting to rigid poly-sheets, to blown-in loose-fill insulation. In some new construction projects it is more convenient or cost-effective to use blow-in insulation. It's very commonly the best way to retrofit structures with insulation, or add to their existing insulation. In many existing homes, it's the only way of installing insulation, short of removing interior wall surfaces.
The loose-fill insulation is blown into place with a large hose, connected to a hopper. The insulation is propelled through the hose by pressurised air. The air is most often created with a turbine-like apparatus and electric motor. Though large truck-mounted blowers may use gas-powered generators, hoppers usually have agitators that feed the loose-fill into the hoses and prevent clogs.
Machines for Different Loose-fill Insulation Types
Machines vary as applications and materials vary; not all insulation blowers are capable of blowing all insulation. Cellulose and fibreglass are very common materials. Fibreglass is the same material as fibreglass batting but cut into fine pieces. Cellulose is often grey and looks like fibrous paper pulp and lint.
Insulation blowing machines come in a variety of sizes. As homeowners have become increasingly aware of energy efficiency, many contractors have added professional insulation retrofitting to their repertoire. The result is an increase in relatively low-cost machines designed for either the homeowner or a general contractor who uses it occasionally. Larger machines are designed specifically for insulation professionals who use them daily. The largest machines are truck-mounted. The entire truck is a insulation blower. It sits outside the structure with the hose extending into the structure, similar to a commercial carpet cleaner.
Machines for Liquid/Foam Insulation
Some insulation blowing machines blow expanding, liquid insulation. These are often for new, commercial applications, but they are also used in residential areas because liquid foam doesn't settle and it can be easier to fill spaces with contours such as complex plumbing and ductwork. These machines work more like pressure sprayers than loose-fill insulation blowers. They are essentially spraying liquid through nozzles (often with extension wands); the liquid polyurethane then expands to many times its original volume before drying. Often contractors who have a machine to spray loose-fill insulation also have a machine to spray liquid insulation.