Types of Insulation

Loose-Fill Insulation
Loose-fill insulation consists of fibers or granules made from cellulose,fiberglass, rock wool, cotton, or other materials. This loose insulation conforms to the space in which it is installed. Loose-fill insulation comes in bags, and is usually blown into cavities or attics with special equipment. Insulation is sometimes blown at relatively high density into a wall or ceiling cavity to resist air infiltration-this technique is called dense-pack. Sometimes loose-fill fibers are cosprayed with an adhesive or water in order to cover irregularly shaped and hard-to-reach areas or to install in walls before drywalling. The insulation dries within a few days and is resistant to settling. This technique is often used with cellulose and is called wet spray. Waiting for the insulation to dry before adding a vapor barrier to the wall can be inconvenient, so some newer processes ("moist spray") use a lot less water to speed up drying time. Some installers also use drying machines.

Loose-fill insulation can also be blown into open wall cavities by attaching a cover to the studs to hold it in. In one system, a reinforced transparent vapor barrier is stapled to the studs and cellulose is blown in through small holes, which are later patched. A similar process involves blowing fiberglass into stud cavities behind a net. Another system uses a temporary frame to pack cellulose, fiberglass, or rock wool densely into the cavities. The densely packed insulation stays in place when the frame is removed.

Batts and Blankets
Batts and blankets are flexible, bound insulation made from glass or cotton fibers. They come in rolls or strips in standard widths, usually to fit between framing on 16- or 24-inch centers; thickness varies depending on the R-value desired. Blankets are available in continuous rolls, whereas batts are precut. Batts and blankets can fit under floors, in attics, and in unfinished easier to walls. Batts are handle than blankets, but blankets can be cut with a knife or razor for a custom fit, minimizing waste.

Rigid Insulation
Rigid insulation is made from fibrous materials or plastic foams and is pressed or extruded into boardlike forms. These provide thermal and acoustic insulation, added structural strength, and air sealing. Plastic foam board (or rigid foam) is the most expensive form of insulation and is made from polyurethane, polyisocyanurate, or polystyrene. It is commonly used in exterior walls (under the siding) and foundations. Since it provides a high R- value per inch of thickness, it is useful where a lot of insulation is desired in cramped quarters, such as cathedral or vaulted ceilings. Foam insulation must be covered with finishing material for fire safety.

Foam in Place
Foam-in-place materials require special equipment to meter, mix, and spray or extrude into place. They provide air sealing as well as insulation. Polyurethane and polyisocyanurate foams have high insulation values per inch. Another type of foam, called Icynene, is also becoming more popular in energy-efficient new construction. These foams can be sprayed into open wall cavities, where they expand to fill the space. Excess material is then trimmed off and, in some cases, used in the attic as loose fill. Spray foams are particularly helpful for insulating difficult areas like the sill plate (the joint between the top of the foundation and the bottom of the house frame).

Not to be confused with the expanding spray foams, which are made of petrochemicals, at least one company has a system that mixes fiberglass,cellulose, or rockwool insulation with a latex binder. The mixture forms a "foam" that conforms well to the spaces it's blown into. It can be used on its own or together with batt insulation to prevent gaps around the batt.

You may want to call a professional air sealing specialist, energy services company, or insulation contractor to seal your house. They should use air leakage detection and measuring tools, such as blower doors and infrared cameras, to help them find the biggest leaks.

Radiant Heat Control
Rather than slowing heat conduction as insulation does, radiant barriersstop heat from moving through the attic by radiation. They are made of aluminum foil with backing. Radiant barriers can reduce attic temperatures in hot climates, so that the difference in temperature between the house and attic is not so great. Based on the same concept, a radiation control(reflective) coating on the roof can lower the summer roof temperature inhot places. Since they reduce radiant rather than conducted heat, it is difficult (and inappropriate) to associate R-values with radiant barriers or radiation control roof coatings.

Now that you know the various type of insulation available, the next step is to figure exactly what you need.

• Insulation 101: How It Works
• Type of Insulation
• Figuring Out What You Need
• Installing Insulation
• Doing it Yourself