Fiberglass consists of glass heated and spun —as in a cotton candy machine — to create fibers that are similar to wool. May include other raw materials and formed into batts or rolls with or without a paper or aluminum foil facing or left loose for blowing into spaces. Used commonly in exterior walls, attics, floors, ceilings and basements. Contains 20 percent to 60 percent recycled content depending upon the manufacturer and the facility. The thickness of the batt will provide the added insulation value. Produced in thicknesses of 3.5 inches to 13 inches, fiberglass batts are rated at R-2.9 to R-3.8 per inch. Use gloves and wear a mask when dealing with fiberglass as the strands can cause irritation.
Rock Wool or Mineral Wool (Slag Wool) are created by recycling iron ore from steel processing or from basalt that is heated and spun into fibers that are formed into batts, rolls or loose fill forms. Used in exterior walls, floors, ceilings, attics or basements. Depending upon the material and the manufacturer, they claim 10 percent to 15 percent, or 70 percent to 90 percent recycled content. Batts are rated for R-values of 3.3 to 4.2; loose fill rates R-2.2 to R-3.3.
Cotton or Denim Batts are created with about 80 percent post-manufacturing fabrics treated with chemical to be fire retardant and mold resistant. The batts most frequently are blue due to their denim content and range from 2-inches thick to 8-inches thick with R-values ranging from 3.1 to 4 to be used in exterior walls (vapor barrier not included), attics, floors and crawl spaces. For attic floors, under floors or in crawl spaces, a mesh or wire support system will be necessary. Some manufacturers produce thinner material for use as water heater blankets, etc.
Cellulose is a product of paper, usually recycled paper or wood with other materials to assist in making it fire resistant. Installed as batts, rolls, blankets, loose fill or blown in, cellulose is used in walls and attics; can be blown in over existing batts. Recycled content is 80 percent and higher, depending upon manufacturer. R-3.1 to R-3.8 per inch as blown-in.
Spray Foam insulation is created from chemicals mixed on-site to form foam that is sprayed between wall studs and on attic floors — especially in areas not easily reached or filled with batts. A can of spray foam can be used to fill holes around pipes, or small trouble spots. The must be installed by professionals who have the appropriate chemicals, equipment and expertise.
• Open Cell foam uses water to spray the polyurethane foam into the cavities. It goes on as liquid and cures within minutes as a foam. The cell walls are often shared, so the plastic chemical portion is lighter and carbon dioxide is contained in the bubbles. As it ages the carbon dioxide depletes and at least 50 percent of the cells are open. This is a soft product and is a vapor retarder. It will dry out if exposed to blown rain or a roof leak. Claims up to R-3.5 to R-4 per inch of depth.
• Closed Cell foam uses a chemical as the spraying agent and traps the chemical within bubbles forming a harder structure. At least 90 percent of the bubbles have separate wall structures. As the foam ages, the chemical off-gases but the bubbles retain their structure. This is a moisture resistant product. Closed Cell foam claims up to an R-6 to R-6.5 (aged) per inch of depth.
Rigid Foam Boards are plastic products and easy to install. Three variations of rigid foam boards are available:
• Expanded Polystyrene has an R-3.6 to 4.2 depending upon density. It is water permeable and is used for structural insulated panels and insulating concrete forms.
• Extruded Polystyrene is strong and waterproof, used often below grade as an insulation of foundations or as exterior wall sheathing. R-5 per inch due to its density makes it a good insulator.
• Polyisocyanurate has the highest R value among the rigid foam boards, but it will absorb moisture so is not used below grade. Produced with a foil facing, when taped at seams Polyiso can be installed on exterior walls as the facing will repel the water. R-6 to R-6.5 per inch.