Insulation Product Types
The least expensive and essential first step to saving energy is to increase thermal resistance of the building envelope with insulation. Manufacturers provide a variety of insulation types and applications, each having varying environmental trade-offs.
Loose-Fill [blown-in]
Product types are: cellulose, rock and slag wool, and fiberglass which are used in attics and walls. Homeowners can rent equipment for blowing in these products, particularly cellulose. All loose-fill insulations are required to detail their installed and settled thickness on the bag label to let consumers know the expected settled R-value. However, loose blown insulation has been known to leave empty pockets of air particularly in sloped ceilings and behind obstacles like truss supports, and is best installed by a specialized contractor.
• Cellulose is made from approximately 75% post-consumer ground-up newspapers treated with non-hazardous boric acid for fire retardant properties. Low-dust cellulose is available to professionals with suitable equipment. According to Climatizer Insulation Ltd., starch is added to the cellulose in the factory and small quantities of water added on site to reduce the dust. The product settles significantly over time and must be over-installed by approximately 10% to compensate. R values increases with depth.
• Rock or Slag Wool, also known as mineral wool, is similar to fiberglass except that it is spun from blast furnace slag and other rock-like materials, instead of from molten glass. They are also blown in dry, but will not settle over time which helps them retain their full R-value.
• Fiberglass is blown in dry and will also not settle over time. Non-toxic polymer is used to bind the 25% recycled content of glass fibers.
Spray-Applied Insulation
Product types are mainly sprayed foam. Cellulose, rock and slag wool, and fiberglass can also be sprayed by adding water but need drying time before closing in the wall. They are always applied by a professional. Sprayed foam has higher initial cost but offers excellent performance [the highest R value] over the life of the house. Spray insulations are commonly used in walls, sloped ceilings and for sealing openings around equipment.
In addition to providing thermal resistance they are excellent for preventing infiltration that normally occurs around connecting points such as between studs or other openings. In exposed areas a fire retardant spray is available. Foams are referred to as closed cell, [2.0 lb./cu. ft, R-6.8/in.] or open cell, [.05 lb./cu. ft., R-3.6/inch].
• Soya Based Spray Foam such as provided by Demilec has an R value of 6/in. It
is made from renewable vegetable oils and recycled plastic bottles. This product is GreenGuard certified and uses a Zero Ozone Depletion Substance as a blowing agent, emits no VOCs [Volatile Organic Compounds] or HCFCs and CFCs [hydrochlorofluorocarbons and chlorofluorocarbons] and contains no formaldehyde or bleach. The material should not be exposed to occupants, but covered with gypsum board or a spray recognized by the local building code. Closed cell foam can also be used on foundation exteriors and under slabs.
• Closed Cell Polyurethane Foam Insulation is made with petroleum oil and various other products. Because the product expands on site, meaning less material is req-uired, some of its carbon footprint is off-set due to a decrease in associated transportation energies compared with other insulations.
• Cellulose is sprayed wet and can achieve R-3.5/in., however, it needs drying time before closing the cavity. The fire retardant chemicals applied to cellulose have been known to cause corrosion of pipes and wiring.
• Rock or Slag Wool is sprayed with water and adhesive at between 10% and 20% moisture content. Can achieve a 2-hour fire-rating.
• Fiberglass can be sprayed into wall cavities with some water and adhesive. It has a slightly lower R-value than cellulose at 3.2/in.
Rigid Insulation
Product types are fibrous materials and plastic foams. The plastic foams include: extruded polystyrene, expanded polystyrene and polyurethane, all of which are most commonly installed on foundation walls and under floor slabs.
They contain millions of densely packed air cells pressed or extruded [extruded products are known to contain HCFCs] into board-like forms and moulded pipe-coverings. Some products are available with a reflective foil surface, and the R-value varies based on material and density.
• Structural Insulated Panels [SIP] an example of an insulated structural system that has a sandwich construction of oriented strandboard or plywood inside and out, with a middle layer of rigid insulation.
• Insulated Concrete Forms [IFC] a second example of an insulated structural system that combines the structural support of concrete poured into forms of rigid foam insulation resulting in a seamless thermal resistant envelope. The expanded polystyrene panels have approximately 30% recycled content and all plastic support web with the forms are made from 100% reused material.
• Reflective Insulation is made from aluminum foils with a variety of backings such as kraft paper, plastic film, polyethylene bubbles and cardboard. A common variation is foil-faced bubble insulation [FFBI] that has entrapped air spaces in bubbles. It gives a minimum R-value of 1.5 and is used to wrap domestic hot water tanks.
Batts and Rolls
The familiar insulation batts and rolls are available as mineral [rock and slag] wool, fiberglass, and cotton/denim which are used in walls, attics, floors, crawl spaces, cathedral ceilings and basements.
They are available with or without vapour barrier facings and can be ordered with flame-resistant facing for areas left exposed like basements.
• Rock and Slag Wool, or mineral wool, as described earlier, is non combustible, and resists moisture. Some products, such as made by Roxul, are also excellent for sound absorption.
• Fiberglass is spun from molten glass and sand into fibers surrounded by tiny pockets of air. In attics air can infiltrate into these air pockets reducing the R value in cold temperatures.
• Natural Cotton/Denim Fiber Insulation is made from cotton and/or scrap denim and bonded with boron, a natural mineral with low VOC. Companies such as Bonded Logic, www.bondedlogic.com, use 85% post-industrial recycled denim. As with cellulose insulation, these materials are combustible and require the addition of fire retardant chemicals.
Hugh Perry is associate editor of SAB MAG.
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