use the toxic formaldehyde backing found in fiberglass, and the manufacture is nowhere near as energy intensive as the mining and production process required for fiberglass. Boric acid is used as a flame retardant. A small quantity of polyolefin is melted as an adhesive to bind the product together (and is preferable to formaldehyde adhesives). Installation is similar to fiberglass, without the need for a respirator but requiring some additional time to cut the material. Cotton insulation costs about 10-20% more than fiberglass insulation. As with any batt insulation, proper installation is important to ensure high energy efficiency. Advantages Equivalent R-Value to typical fiberglass batts Recycled content, no formaldehyde or other toxic substances, and very low toxicity during manufacture (only from the polyolefin) May help qualify for LEED or similar environmental building certification programs Fibers do not cause itchiness, no cancer risk from airborne fibers Disadvantages Difficult to cut. Some installers may charge a slightly higher cost for installation as compared to other batts. This does not affect the effectiveness of the insulation, but may require choosing an installer more carefully, as any batt should be cut to fit the cavity well. Even with proper installation, batts do not completely seal the cavity against air movement (as with cellulose or expanding foam). Still requires a vapor retarder or barrier (unlike cellulose) May be hard to dry if a leak allows excessive moisture into the insulated cavity Loose-fill (including cellulose) Loose-fill materials can be blown into attics, finished wall cavities, and hard-to-reach areas. They are ideal for these tasks because they conform to spaces and fill in the nooks and crannies. They can also be sprayed in place, usually with water-based adhesives. Many types are made of recycled materials (a type of cellulose) and are relatively inexpensive. General procedure for retrofits in walls: Drill holes in wall with hole saw, taking firestops, plumbing pipes, and other obstructions into account. It may be desirable to drill two holes in each wall cavity/joist section, one at the bottom and a second at the top for both verification and top-off. Pump loose fill into wall cavity, gradually pulling the hose up as the cavity fills. Cap the holes in the wall. Advantages Cellulose insulation is environmentally preferable (80% recycled newspaper) and safe. It has a high recycled content and less risk to the installer than fiberglass (loose fill or batts). R-Value 3.4 – 3.8