Siding works a lot like skin. It serves as the first line of defense against unwanted air infiltration (pollen, dust mites, drafts) and moisture penetration (mold and rot). If that isn’t enough, siding is the single largest exterior element. Faded, weathered siding can make a home look old before its time; new siding can make an old house look brand new.
Trying to perform this homeowner hat trick—accomplishing protection, good looks, and longevity—isn’t easy. Add environmental and health concerns to that mix, and choosing among the options gets even more confusing. Dozens of products claim to be the “ultimate answer,” but most offer only a partial solution.
Selecting the right type of siding involves balancing all of the immediate costs (material, installation, maintenance) with future costs (longevity, effects of long-term exposure, eventual biodegradability or recyclability). If possible, also try to factor in the unseen environmental costs of manufacturing and transportation.
For those considering residing, sometimes the best advice might simply be a fresh coat of paint.
Solid wood siding continues to be the most popular choice in North America because, in many ways, wood is still the ideal siding material. Renewable, locally available, requiring little production energy, and ultimately biodegradable, wood siding—bevel lap, ship lap, board-and-batten, shingles, and shake siding—is safe to cut and easy to install. But wood siding installation generates a fair amount of waste and requires frequent maintenance. Of additional concern, the desire to mill the heartwood from the most weather-resistant woods, cedar and redwood, has led to overharvesting and clear-cutting.
If you already have wood siding, the most environmentally responsible choice is to keep what you have. Thousands of wood-sided homes along the East Coast have withstood more than a century’s worth of harsh weather, and with regular maintenance they can last just as long as replacement siding. But be mindful of potential toxins that could be emitted by scraping and sanding. Lead was a common paint additive until the mid-1970s. In some areas, shingles were treated with creosote for extra durability.
For the most responsible option, look for preweathered salvaged wood from old barns, other buildings, and bridges, or newer-looking stock that has been resawn from larger beams. In addition, the Forest Stewardship Council (FSC) sustainably certified forests offer an increasing supply of wood products.
Engineered wood was born from the desire to find a use for the waste created by milling wood products and to use otherwise unsuitable trees. Wood chips are coated with binders and resins, and then reassembled into panels and boards. The resulting product is more uniform and more dimensionally stable than solid wood. Although the products such as oriented strand board (OSB) and fiberboard can make use of lumber by-products and otherwise unsuitable trees, critics contend that OSB encourages clear-cutting and the harvesting of immature forests.
Also, carpenters complain that engineered boards are often heavier and less rigid than the real thing. Engineered panels and planks are often more vulnerable to moisture, particularly at the edges and ends, and can degrade faster than wood. Some hardboard siding has failed or deteriorated due to moisture penetrating the siding. As a result, several class action lawsuits have been filed against siding manufacturers, including Masonite, Louisiana-Pacific, and Weyerhaeuser. Not all hardboard siding has experienced failures or deterioration. The failures were a result of a flawed product design compounded by improper installation and poor maintenance.
Fiber cement, or cementitious, siding isn’t as new as some people may think. Cement siding was hung on thousands of homes several decades ago. That product also resembled wood, did not burn, and wore like iron. But it was pulled from the market when the magic ingredient, asbestos, was declared a carcinogen. (If your home has old-style cement shingles, consider a coat of paint. Asbestos fibers and dust are released only when the shingles are broken or abraded. Abatement/removal is expensive, can potentially increase exposure, and only adds to the debris in your local landfill.)
The latest generation of fiber cement panels has replaced asbestos with wood fiber, creating planks and panels that will not rot, burn, or feed an insect colony. Good dimensional stability means that paint sticks better and lasts almost twice as long as on wood. Fiber cement’s other big advantage is price; this wood look-alike costs about half as much as the real thing.
There are downsides. For starters, special wood fibers are required to withstand the heat and alkalinity of the manufacturing process. When wood is obtained overseas, as it is by James Hardie, a leading fiber-cement supplier that buys its wood from Australia and New Zealand, the transportation of both the raw materials and the eventual siding from the plant to your home creates a significant energy burden.
Finally, installers need to exercise caution when working with this product. Cutting fiber-cement is dusty work, and the dust contains silica, which can lead to lung damage. Dust-collecting saws or dust-free pneumatic or electric shears should be used whenever possible.
Synthetic stucco is infamous for catastrophic failure, prompting millions of dollars’ worth of lawsuits, but conventional, cement-based stucco has provided a durable, low-maintenance siding option for several thousand years. Unlike the synthetics, lime plaster allows water vapor to escape and is fairly crack resistant. Natural earth pigments can be added to the final coats to provide a wide variety of colors.
Unfortunately, plaster isn’t one of the friendliest materials to work with. Most water-resistant plasters contain lime, which is caustic and can cause nasty burns to eyes or exposed skin. (Earthen plasters are friendlier and can sometimes be harvested right from the site but may not be allowable by local codes unless stabilized with oil-based emulsions.) Both products require multiple coats of laborious hand troweling.
The Tin Men of the 1950s did much to malign steel and aluminum (a later substitute) siding. Much of the criticism was because of shoddy workmanship and original trim, and architectural details were either covered over or removed. In terms of durability and recyclability, metal siding deserves consideration. Aluminum siding requires a great deal of energy to produce from raw ore, but it is typically made from recycled materials. At the end of its lifespan, it is easily recycled. Steel and aluminum sidings are finished at the factory, reducing the chemicals used on the job site and eliminating the outgassing produced by curing paints and finishes. After 15 to 25 years, when the factory finish begins to fail, metal siding can be painted just like wood.
Vinyl is one of the newest options to hit the siding market, yet it has already captured nearly half of the new home and residing markets. Vinyl is inexpensive, easy to install, and requires very little maintenance. “Vinyl is final” is the standard builder battle cry.
However, most people don’t realize all of vinyl’s hidden costs. In addition to polyvinyl chloride (PVC), vinyl siding contains a caustic brew of plasticizers (such as phalates), stabilizers (containing heavy metals such as lead), fungicides, and other toxic substances. These chemicals can escape into the surrounding air, water, and soil. Although flame resistant, at high temperatures PVC produces hydrogen chloride, which spreads faster than the flames and can kill occupants long before the fire reaches them.
Lastly, vinyl siding is difficult to recycle. Although a few manufacturers advertise that their products are made from recycled materials, others claim that “virgin” PVC offers better performance.
The most significant unseen cost of vinyl occurs during the manufacturing process. PVC is one of the greatest producers of dioxin, a cancer-causing chemical that can also cause birth defects years later. The U.S. Environmental Protection Agency (EPA) suggests that there is no safe level of dioxin exposure. In her documentary Blue Vinyl, filmmaker Judith Helfand outlines the harmful impacts of vinyl production on workers and the environment. In 1987, the town of Reveilletown, Louisiana, became so contaminated that all 106 residents were relocated and every structure was torn down. Based in part on her findings and the EPA’s reports, the U.S. Green Building Institute is proposing rewards for builders who find ways to eliminate vinyl products altogether.
Saving Wood Beneath the Skin
If you’re interested in saving trees, choosing a nonwood siding is a good start, but consider this: Of the 11,000 board feet used to build a midsize house, siding accounts for about 10 percent. Framing and sheathing make up more than 70 percent. Whether you’re building a new home or planning a major remodel, here are some options that can help you reduce your wood consumption:
Oriented Strand Board (OSB): Nearly as strong as plywood, OSB can be made from wood waste and small fast-growing trees, and is available as an FSC-certified product from at least one company. A few manufacturers are making OSB from straw. Strawboard panels use less binders, are more water-resistant, and cost about as much as wood fiber panels.
Stresskin Panels: OSB sandwiching an expanded polystyrene core can make a strong, energy-efficient wall completely without studs.
Fiberboard: Tons of non-deinked newspaper and recovered wood waste are being made into structural and nonstructural sheathing. One manufacturer estimates that using their product to build a standard-sized house can save as many as six trees.
Gypsum: Gypsum sheathing is a common choice for commercial work but isn’t well known in residential construction. Gypsum is a suitable backer for tile, stucco, or brick veneer, but you’ll need additional nailer base for shingles, shakes, or clapboards.
Antique Woods & Colonial Restoration
reclaimed and remilled wood products
Stress skin panels from straw
Valley Forge, Pennsylvania
Fiber cement WeatherBoard siding
Environmental Home Center
reclaimed redwood shingles
Catawba engineered wood siding
James Hardie Building Products
Mission Viejo, California
fiber cement Hardiplank siding
Old Grain—Reclaimed Wood Specialists
Roy Martin Lumber
Tuff-Strand FSC-certified OSB
Superior Hardwoods and Millwork
Fiberock Aqua-Tough gypsum sheathing