General Guidelines for selecting a cladding system:
- Choose a system that will be serviceable at least through the end of the first mortgage term, usually 30 years.
- Compare life-cycle costs for siding, including first cost, maintenance costs, and replacement costs to determine best selection.
- Use products that come from sustainable sources or those made with recycled or waste material to reduce overall environmental impacts.
- Use products that are recyclable.
Options and Analysis
|Cladding types||Expected Life (years)||cost/sf (material + labor)||cost/sf/yr of expected life||End-of-Life||Practice|
|stucco||75 (depends on maintenance)||$4.18||$0.075||Landfilled (metal lath recyclable)||standard|
|brick||100+(typically life of the bldg)||$9.70-$15.30||$0.078||Possible reuse||standard|
|wood||25-75 (depends on maintenance)||$3.07*-$4.95||$0.080||Biodegradable||standard|
|fiber-cement||501||$2.31-$2.75||$0.051||Recyclable (currently no programs available)||May require some training (cutting & sealing joints)|
|vinyl||35||$1.75-$2.06||$0.076||Recyclable (currently no programs available)||standard|
|wood-resin/plastic composite||20-30||not available||not available||Difficult to recycle||standard|
Estimate of expected product life is based on LCA data from Athena EIE 3.0.3
Cost information is based on Means Cost Works 2007.
Cost per year of expected life does not include maintenance costs.
*$3.07 for wood cladding is for rough sawn, stained, white pine 1"x8"
Cementitious materials, such as traditional stucco and brick, are the most durable, wear well over time, and have the longest expected serviceable life. Properly maintained, they can last 100 years or more. Both brick and stucco require maintenance on joints where water infiltration may occur. Maintaining sealants, flashings, and weeps within the system is essential to full life cycle performance.
Fiber-cement siding, which is not prone to rot or infestation1, is durable, with a 50-year life expectancy (dependent on regular maintenance every 5-7 years). Sealant and joint detailing are also important components of the overall durability of fiber-cement products and installations. When installed and maintained properly, fiber-cement siding should prove more durable than wood cladding.1 Steel and aluminum siding are also relatively durable choices.
Although the Athena Institute has determined the average life expectancy for wood siding in Minnesota to be about 25 years, they note that with proper painting and maintenance, it can easily last the lifetime of a building. Similarly, hardboard products require more maintenance—painting and sealing seams—to ensure their full life cycle. Composites, with their blend of resins, are more durable and stand up better to moisture than hardboards.
Vinyl has a 35-year life expectancy. However, environmental exposure causes vinyl plasticizers to deteriorate, causing siding to fade and become brittle. Since painting vinyl is not advisable, faded or chipped vinyl siding may require replacement before its full life expectancy.
As the house's first line of defense against moisture intrusion, correct installation and maintenance of the cladding system, regardless of type, is critical to the continued function and durability of the exterior wall system. This includes proper flashing and detailing of openings and continued maintenance, such as painting and tuck pointing.
Vinyl siding is widely used today because it has the lowest first cost, low maintenance, and is relatively durable. Fiber-cement board is gaining popularity due to its relatively inexpensive cost and anticipated longevity. First cost for fiber-cement siding is only slightly more than vinyl. Wood siding is roughly twice the cost of vinyl and at least 50% more expensive than fiber-cement. As with many building materials, those with highest first costs, such as brick, stucco, and wood, have the greatest durability. Per year of expected life, the costs of wood, stucco, and vinyl are roughly equivalent (not considering maintenance costs). Fiber-cement board's cost per year of expected life is significantly less than other options.
Life Cycle Analysis Analysis (measures are given per square foot of cladding)
Cladding Global Warming Potential (lbs of CO2) Embodied Energy (Btu) Solid Waste (lbs) Air Pollution Index Water Pollution Index Brick 15.0744 111,691 2.3758 1.3953 * Stucco 2.3576 23,769 0.2179 0.1388 * Steel Cladding 11.8583 49,891 1.7274 0.6918 1.6894 Wood Cladding 1.4525 15,405 0.2282 0.1259 * Vinyl Cladding 5.0032 45,313 0.3527 5 0.4247 *
LCA information is based on Athena EIE 3.0.3
* Although all choices have negative impacts on water quality, their impact compared to steel cladding is negligible.
Life Cycle Analysis Analysis (measures are given per sf of cladding per year of expected life)
Global Warming Potential
Because of their energy-intensive manufacturing processes, brick and steel have the highest amount of carbon dioxide emissions per square foot of cladding. The environmental impacts of manufacturing are diminished if materials are well maintained and last for longer periods. For example, because brick has an expected product life more than three times that of vinyl, its global warming potential per year of life is actually comparable to vinyl. This is illustrated in the second series of LCA graphs, which display LCA impacts per square foot per year.
Wood siding alternatives, such as cedar shakes and bevel or lap siding, have the lowest primary energy use and total embodied energy. If sustainably harvest, they also have the lowest overall environmental impact. However, they do require the most maintenance over time in order to maintain integrity and prevent mildew and rot. Brick leads the group in highest total embodied energy, followed by steel and other metal siding materials. However, products like brick are comparable to vinyl when their extended life cycle is taken into account.
Air and Water Pollution
Brick and steel have the highest air pollution indices, caused primarily by raw material extraction and manufacturing processes. Steel also has the highest negative impact on water use, from extraction through the full manufacturing cycle. Vinyl siding has a significantly larger environmental impact than wood-based and stucco siding. In addition, the production and eventual disposal of vinyl is associated with environmental pollutants such as dioxins, PCBs, and phthalates. Wood from non-sustainably managed forests can create significant environmental impacts such as habitat loss, erosion, and stream sedimentation.
Hardboard and composite products use waste or low-quality materials, which reduces the energy used to extract, harvest, and process virgin materials. However, the manufacturing processes for these products are often highly energy-intensive.
Steel and aluminum are highly recyclable and are currently being made with significant proportions of recycled material, thereby reducing their initially high embodied energy. Fiber-cement siding can be reground and used, in some cases, as fill, but there is currently no program for incorporating recycled materials back into production. Stucco is not recyclable, although the metal lath in the system is. Brick can be salvaged, cleaned, and reused or ground up for landscape use or fill. Wood is biodegradable, but stains and paints can affect its reuse and limit its use as mulch or landscape amendment. Vinyl can be recycled, depending on the quality of the PVC. However, there are no programs currently in operation to return the material and it is generally landfilled when removed.
All of the siding selections examined here are common and use standard installation methods, although fiber cement siding installation may require some additional training for cutting the material and proper sealing of joints.
1 "Fiber Cement Siding." ToolBase Services Website. 2008. ToolBase Services 27 June 2008. www.toolbase.org/Technology-Inventory/walls/fiber-cement-siding