These products are environmentally attractive because they need to be replaced less frequently or their maintenance has very low impact, both of which can reduce costs as well as environmental impact.
Robust answers on typical service life of products can be hard to come by, however. In GreenSpec we reserve this criterion for products where the material is clearly more durable than alternatives, such as an exceptionally traffic-resistant polyurethane floor finish. We refer to standardized tests for durability when they are available and appropriate.
We also consider “appropriate durability”: long life is more important in a building envelope than in interior finish materials that will be replaced for aesthetic reasons. Here, reduced maintenance can be particularly important. An example is resilient flooring that doesn’t require regular waxing: an unnecessary use of resources and a health hazard.
Magnum Board
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Just how low the VOC level needs to be for a given product to qualify for inclusion in GreenSpec depends on the product category. For most products, we require certification to California’s health-based emissions standard, CDPH Std Method v1.1 standard (also referred to as California Section 01350), which tests a product’s resultant VOC concentrations in the space after a given period of time. For wet-applied products like paints, caulks, and adhesives, we still also look for VOC content instead of, or in addition to, verified low emissions; this is because emissions testing doesn’t adequately test initial offgassing, and VOC content is currently the only widely available proxy.
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While resilience—the ability to weather natural disasters and maintain livable conditions in the aftermath of disruptive events—is mostly an issue of building design and community preparedness, certain products can help. For example, almost all heating systems require electricity to operate even if their primary fuel is oil, gas, or wood pellets; systems that allow operation even if grid electricity is not available are more resilient in the event of power outages. Rainwater harvesting, water storage, composting toilets, and waterless urinals contribute to resilience not only in drought-prone areas but also during power outages in any home dependent on well water. Solar water heating systems that can operate without utility power, and back-up power systems that are more energy-efficient than standard generators, may have this attribute.
Magnum Board structural panels are made from magnesium oxide (MgO)/magnesium chloride cement along with cellulose, perlite, and proprietary additives. Fiberglass is used for reinforcement. These panels have low-toxicity, maintain their structural integrity when wet, and resist insects and mold. The perlite in these boards makes them lighter than some other cementitious panels and offers some sound resistance. Magnum Board makes products for sheathing, soffits, fascias, walls, ceilings, and backing board in 4'x8', 4’x9’, 4'x10', and 4'x12' dimensions and 1/8" to 1" thicknesses. These panels are available with tapered edges and are best suited for use in areas prone to insects, flooding, or hurricanes.
Products listed here provide moisture resistance along with racking shear and transverse load resistance, and have one or more of the following attributes: FSC-certified content, urea-formaldehyde-free binders, low-toxicity borate insect treatments, superior insulation, or other environmental advantages.
Some sheathing board products include an insulation layer, which is beneficial in reducing thermal bridging through framing elements while providing sheathing in one product, reducing installation costs.
Cement-based panels can offer durability and indoor-air-quality benefits when used where moisture, mold, or insects are a problem, or where fire-rated panels are specified, and GreenSpec lists them due to these benefits. However, their product is energy intensive, relative to conventional sheathing or wallboard.
Cementitious sheathing products are made from portland or magnesia (magnesium oxide; MgO) cements, fillers, and reinforcement. Both portland and MgO cements release carbon dioxide as result of calcination, but MgO is fired at a lower temperature (approximately 1290°F vs 2700°F, respectively) and for less time, resulting in approximately 20%-40% less manufacturing energy. Unfortunately, MgO panels are currently made in China and are not widely distributed in the U.S., so they can be expensive, whereas portland cement panels are often made regionally across the U.S.
Effective moisture-management should be the primary consideration in selecting a backerboard product for wet areas, such as tub and bath surrounds. There are three major types of tile backer board appropriate for these applications: cementitious, coated glass mat, and fiber-cement.
Coated glass mat products have a gypsum core with glass fibers sandwiched between fiberglass surface mats. Unlike paper-backed gypsum board, glass mat products are not recyclable, but neither are other backerboards for wet areas. With cementitious and fiber-cement boards a primary environmental concern is the embodied energy of portland cement. With these boards, consider products with below average use of portland cement. This is often accomplished through replacement with fly ash, a byproduct of coal combustion. While concerns have been raised about fly ash, at this time GreenSpec does support its use in products such as cementitious backerboard where it lowers the product’s embodied energy and the fly ash is chemically or physically locked up, as described in this 2010 EBN Editorial.
Backerboard products listed here are included primarily for their durability, although other environmental issues play a role. These products may be coated glass mat boards, or either cementitious or fiber cement boards—with preference given to those that have reduced use of portland cement. To the best of our knowledge these products do not include hazards of high concern.
Using underlayment products beneath wood, tile, resilient flooring, or carpet and carpet cushion provides a level surface and helps insulate floors from sound transmission and, to a limited extent, heat loss.
Cork rolls and sheets can provide resilience to the floor system with significantly less thickness than fiberboard products or a gypsum-cement poured-in-place slab. And use of a sound-deadening underlayment below a hard-surface floor can reduce the need to further control sound transmission with carpeting or rugs.
Plywood is often required as an underlayment for resilient flooring, ceramic tiles, and carpeting; and exterior-grade particleboard can also be used is some applications. Some products combine the functions of subfloor and underlayment in one product, minimizing resource use. Lauan or other tropical wood based products should be avoided unless FSC-certified.
Environmentally preferable materials for flooring underlayment listed by GreenSpec include natural cork, strawboard, products that are inherently moisture- and mold-resistant, and products with recycled content. Preference is given to no-added-formaldehyde (NAF) products, but no-added-urea-formaldehyde (NAUF) particleboards and plywoods also have very low formaldehyde emissions.
LEED Credits
EQc4.1: Low-Emitting Materials—Adhesives&Sealants
IEQc4.1: Low-Emitting Materials—Adhesives and Sealants
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