Cellulose insulation is made of almost entirely of recycled materials, mainly newspaper. It can cover harder to reach areas such as the small gaps around pipes and electrical wires. It's treated with boric acid, which makes it flame resistant and prevents mold from growing.

The roof of the new addition is being insulated to retain all the heat generated from the radiant heating system. Paul Johnson of Alpine Insulators reviews the installation process. The first step involves installing netting that is breathable so air can escape once the cellulose is installed. The netting is fire-retardant and stapled in place to hold dense-packed cellulose in place. Bales of cellulose are emptied into a machine located in an on-site truck that shreds the cellulose before pumping it at high pressure into the cavities of the roof. In this case, the insulation cost about $2.25 a square foot. Cellulose is a great thermal insulator and sound attenuator. In the interior partion wall where the bathroom will be located, cellulose will be installed directly against the drywall. Bill Hulstrunk of National Fiber reviews some of the properties of cellulose insulation, which has been around since about 1920 and used extensively since 1970 in both new and existing construction. Borates are added to make the cellulose fire-retardant, and mold and insect resistant. Because of the added borates, a propane torch can be put to the cellulose without igniting it. In a field test, a penny can be put on top of the cellulose and melted without the heat penetrating the material. These borates are naturally occurring and the cellulose itself is made of 83 percent recycled content, making this type of insulation an environmentally conscious, "green" choice. The cellulose in this house is being used in an unvented application. Because the material is packed very tightly, it reduces the chance that warm, moist air will penetrate the cavity and create mold growth.

Bob meets up with Joe Sheridan from Energy Guard to learn more about the US Greenfiber Cocoon cellulose insulation application that is taking place in the barn. This is not a do-it-yourself process. A mesh material is first attached behind the wall cavities to hold the cellulose in place until the drywall is applied. The cellulose is essentially ground up newspaper treated during the manufacturing process with borates to resist fungus growth. It's mixed with a litle moisture and blown into the stud cavities. Product that falls onto the ground is vacuumed up and sucked back to the truck where it is remixed and blown back out. While one installer blows the insulation in, a second man follows with a stud scrubber, leveling the cellulose with the studs. The goal is to create a tight fit eliminating air movement through the wall. One can achieve an R-factor of R-13 in a 2 x 4 wall and an R-21 in a 2 x 6 wall, R-factors that will be maintained even in extreme temperatures. Within 24 hours after application the moisture content drops below 25% allowing sheetrocking to proceed. Another benefit of the product is sound attenuation. Upstairs in the attic, Joe's crew is doing a dry application. The cellulose is blown in under pressure. The hose is fed down to the bottom of the cavity and pulled back as it fills up. A proper vent in the ceiling is not necessary because the insulation is so dense that air doesn't travel through the insulation and miosture therefore never gets out to the roof sheathing. The price of the Cocoon product is comparable to fiberglass insulation.