By: John Riha
Published: September 2, 2009
Selecting green siding is a matter of weighing trade-offs in longevity, insulation, biodegradability, maintenance, and, in some cases, cost.
When choosing siding, consider its sustainability. Sustainability is an estimate of how long a material will last; if the material can be recycled; if it contributes to health concerns; and if it'll readily biodegrade in a landfill. Maintenance, too, is a key consideration. High-maintenance materials that require regular upkeep, such as repainting, and use additional resources and energy over their lifecycle, are less sustainable.
A siding replacement project offers an excellent opportunity to boost your home's energy performance and make your house healthier. Adding a house wrap (which prevents water infiltration and air leaks) and rigid-foam insulation is one of the best ways to reduce energy consumption and protect your home from moisture condensation inside wallsâ€”a major source of mold problemsâ€”no matter what type of siding you choose.Â
Adding insulation increases R-valueâ€”a measure of insulation performance. A house with 3-1/2-inch stud walls filled with fiberglass insulation has an R-value of about R-12. Adding rigid foam and house wrap can boost insulating performance to between R-16 to R-20, reducing your annual energy costs 5% or more.
Siding replacementÂ has proven value. A siding replacement project using foam-backed vinyl siding returns about 72% of its initial cost at resale, according to Remodeling Magazineâ€™s Cost vs. Value Reportâ€”one of the higher returns listed in the annual survey.
Because many types of siding are extremely long-lasting, they can be considered green options, but without a premium price. However, improving thermal performanceâ€”and, therefore, boosting the siding's greennessâ€”with house wrap and rigid-foam insulation adds costâ€”about $1,800 for an average house, according to Fine HomebuildingÂ magazine. Many green consumers feel that contributing to a healthier, sustainable environment is more important than higher initial costs.
House wrap is a thin, tough, semi-permeable membrane that's applied over the outside of wall sheathing and under the siding. It's designed to block water and reduce air infiltration while allowing moisture vapor to pass through.
Sustainability: Extremely durable and long-lasting, this flexible, plastic material is recyclable.
Energy efficiency: Using house wrap, along with properly sealed joints at windows and doors, can reduce air infiltration and save on annual energy bills. Some varieties, such as DuPont's Tyvek ThermaWrapÂ and Low-E Housewrap from Environmentally Safe Products include heat-reflective layers that increase insulation performance by a factor of R-2.Â
Cost: 25 cents to 50 cents per sq. ft., installed
Rigid-foam sheathing is lightweight, easy to apply, and comes in a variety of thicknesses. Unlike fiberglass insulation, which fits between studs, sheathing blankets the entire exterior wall. It can be applied directly over existing wall materials, such as hardboard, stucco, and wood, providing a smooth substrate for new siding.
Sustainability: The manufacture of extruded polystyrene (XPS) sheathing is associated with the production of chlorofluorocarbons (CFCs), which damage the ozone layer, although some manufacturers are researching CFC-free production methods. Expanded polystyrene (EPS) foam sheathing doesn't produce CFCs and is considered environmentally friendly. EPS can be recycled but doesn't degrade readily in landfills.
Energy efficiency: Insulating values of R-3 to R-7 per inch thickness.
Cost: 20 cents-$1 per sq. ft., depending on thickness and thermal performance.
Insulated vinyl is similar to regular vinyl siding, except it includes a layer of EPS foam insulation. Its thickness makes it more rigid and easier to work with than regular vinyl.Â
Sustainability: Vinyl requires little maintenance and will last 30 to 50 years, but it's made from polyvinyl chloride (PVC), a chemical compound that doesn't degrade in landfills. During manufacturing, PVC produces byproducts that include dioxin. Vinyl siding can be recycled.
Energy efficiency: Â Adds approximately R-3 to walls
Cost: $3-$8 per sq. ft., installed; 15-30% more expensive than regular vinyl
Fiber-cement siding is a low-maintenance product made from sand, Portland cement, clay, and wood pulp fibers. It's termite-proof, fire-resistant, and doesn't rot.Â
Sustainability: Extremely durable and long-lasting, it's available with low-maintenance finishes that last for decades. But fiber-cement carries high embedded energyâ€”the energy necessary to fire the kilns that heat its raw materials. Any energy expended toward a material adds to its carbon footprint. The newest varieties are lighter and include more recycled material.
Energy efficiency: Negligible R-value, but its superior stability helps keep the building envelope free of cracks and caulk failures.
Cost: $5-$9 per sq. ft., installed
Unmatched beauty makes wood a premier choice for siding.
Sustainability: Although a precious natural resource, wood is a renewable product that can be recycled and readily degrades in landfills. To ensure the wood products you buy are harvested from sustainable, managed forests, look for certification stamps from the FSC (Forest Stewardship Council) and the SFI (Sustainable Forest Initiative). Wood siding is a high-maintenance siding that requires refinishing every two to five years.
Energy performance: Wood is a natural insulator, but as a siding it offers a minimal R-value of about R-1.
Cost: $6-$9 per sq. ft., installed
Traditional stucco is made from sand and Portland cement mixed with water to make a workable plaster. Modern stucco often includes epoxies to harden the material. It's tough, durable, and resistant to insects and fire. Well-maintained stucco will last for the life of the house.Â
Sustainability: Eco-friendly varieties of stucco are made with an earth-and-lime mixture instead of Portland cement and epoxy, reducing the embedded energy and CO2 emissions associated with cement production. Painted stucco requires periodic touch-ups and repainting every 5-7 years.
Energy performance: Negligible thermal performance, but effective at reducing air infiltration while remaining permeable to moisture vapor.
Cost:Â $6-$9Â per sq. ft., installedÂ
Engineered wood products are made from wood fibers, resins, and wax. They're pressed in molds to create panels resembling real wood lap siding and shingles.
Sustainability: The high wood waste content of engineered siding boosts its sustainability factor. Engineered siding comes with baked-on factory finishes that reduce maintenance, but warranties of about 20 years are less than for other types. It easily biodegrades in landfills.Â
Energy performance: NegligibleÂ
Cost: About $2-$4 per sq. ft., installed
John Riha has written seven books on home improvement and hundreds of articles on home-related topics. HeÃs been a residential builder, the editorial director of the Black & Decker Home Improvement Library, and the executive editor of Better Homes and Gardens magazine. His standard 1972 suburban house has been an ongoing source of maintenance experience.
The Beshears-Smith Team
Eva Beshears & Jazell Smith
Broker SalespersonÂ with Murney Associates, Realtors