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Insulweb, manufactured by Hanes Industries and offered through a variety of distributors, is 100% polypropylene mesh used in the installation of blown cellulose insulation… Read more
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  • Before specifying efficient heating and cooling equipment, it’s important to do what we can to reduce heating and cooling loads. Insulation is one of the key products to consider here, but because there are so many insulation products on the market, we look for additional benefits. Examples include cellulose insulation with recycled content, mineral wool insulation with no flame retardants, and fiberglass insulation with no formaldehyde binders. Other products in this area are high-performance windows and glazings, products that contribute to building airtight envelopes, products that reduce thermal bridging, and window-retrofit products.

    With products in this area under constant development, we are always refining our approach. For example, as we have learned about insulation products with hazardous flame retardants and blowing agents that have high global warming potential, we have removed those products from GreenSpec, pending manufacturing changes. We encourage building professionals to pressure manufacturers for those changes through specification language and purchasing decisions.

Tristan Roberts
Editorial Director

Insulweb, manufactured by Hanes Industries and offered through a variety of distributors, is 100% polypropylene mesh used in the installation of blown cellulose insulation. It is stapled to wall studs and is transparent to allow for the inspection of the insulation as it is being installed. Hanes Industries processes sheets of Insulweb thousands of yards long and up to 120" wide and remills Insulweb into smaller rolls for distribution. Insulweb is available in many sizes.

Blown insulation can be any fiber insulation material that is blown into place, usually in a wall cavity or attic. The most common blown insulation materials are cellulose and fiberglass, but mineral wool, sheep’s wool, and other materials are also used.

Cellulose insulation has several environmental advantages. Most products contain 75%–85% recycled newspaper (usually post-consumer) and borate and/or ammonium sulfate flame retardants, which are benign in comparison with other common flame retardants.

Dry cellulose can be blown into a closed framing cavity in a “dense-pack” application, or blown or poured into the floor cavity of an attic or ceiling. “Stabilized” cellulose, used primarily in attic floor applications, contains a small amount of acrylic binder to prevent settling and shrinkage. For information on damp-spray cellulose, see 07 21 29 – Sprayed Insulation. Rental equipment is commonly available for applying loose-fill cellulose, while hiring a contractor is necessary for a dense-pack application.

The energy performance of dense-pack cellulose is comparable to that of high-density fiberglass batts at roughly R-3.7 per inch, but cellulose insulation generally fills cavities more completely—especially around wires or pipes, or in oddly sized framing cavities—and so is more effective at preventing convection heat losses.

Loose fiberglass is most commonly blown into closed cavities or applied through a specialized mesh that has been stretched across the inner face of framing members; a form including binder can also be sprayed into an open cavity (see also 07 21 29 – Sprayed Insulation). Fiberglass and mineral wool can release respirable fibers into the air. While these fibers are less likely to be carcinogenic than they were in older formulations, they are respiratory irritants. Blown fiberglass and mineral wool should only be installed if the fibers can be prevented from getting into occupied space or air distribution systems.

Products listed here have recycled content, are derived from agricultural waste, offer superior moisture or air leakage performance, or impart lower indoor air quality concerns than other products.

LEED Credits

EAc1: Optimize Energy Performance

EAp2: Minimum Energy Performance

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