Siding is the outer covering or cladding of a house meant to shed water and protect from the effects of weather. On a building that uses siding, it may act as a key element in the aesthetic beauty of the structure and directly influence its property value.
Siding may be formed of horizontal or vertical boards, shingles, or sheet materials. In all four cases, avoiding wind and rain infiltration through the joints is a major challenge, met by overlapping, by covering or sealing the joint, or by creating an interlocking joint such as a tongue-and-groove or rabbet. Since building materials expand and contract with changing temperature and humidity, it is not practical to make rigid joints between the siding elements.
Siding may be made of wood, metal, plastic (vinyl), masonry , or composite materials. It may be attached directly to the building structure (studs in the case of wood construction), or to an intermediate layer of horizontal planks called sheathing.
Wood siding in overlapping horizontal rows or "courses" is called clapboard or weatherboard.
In colonial North America, Eastern white pine was the most common material. Wood siding can also be made of naturally weather-resistant woods such as redwood or cedar. The most common wood siding type is Bevel siding, which is made with beveled boards, thin at the top edge and thick at the butt, placed in overlapping layers.
Jointed horizontal siding (also called "drop" siding) may be shiplapped or tongue and grooveed (though less common). Drop siding comes in a wide variety of face finishes, including Dutch Lap (also called German or Cove Lap).
Plywood sheet siding is sometimes used on inexpensive buildings, sometimes with grooves to imitate vertical shiplap siding. (One example of such grooved plywood siding is the type called T1-11 ["tee-one-eleven"—often written T111 ].)
Wood siding is very versatile in style and can be used on a wide variety of homes in any color palette desired.
Though installation and repair is relatively simple, wood siding requires more maintenance than other popular solutions, requiring treatment every four to nine years depending on the severity of the elements to which it is exposed. Ants and termites are a threat to many types of wood siding, such that extra treatment and maintenance that can significantly increase the cost in some pest-infested areas.
Wood is a moderately renewable resource and is biodegradable. However, most paints and stains used to treat wood are not environmentally friendly and can be toxic. Wood siding can provide some minor insulation and structural properties as compared to thinner cladding materials.
Wood clapboard is often imitated using vinyl siding or uPVC weatherboarding. It is usually produced in units twice as high as clapboard. Plastic imitations of wood shingle and wood shakes also exist. Vinyl or plastic siding has grown in popularity due to the generally low maintenance and low cost appeal it offers. It is among the easiest forms of siding to install, making it the top choice for many new home builders today.
Since plastic siding is a manufactured product, it may come in unlimited color choices. Historically vinyl sidings would fade, crack and buckle over time, requiring the siding to be replaced. However, newer vinyl options have improved and resist damage and wear better. Vinyl siding is sensitive to direct heat from grills, barbecues or other sources. Unlike wood, vinyl siding does not provide additional insulation for the building, unless an insulation material (e.g., foam) has been added to the product. It has also been criticized by some fire safety experts for its heat sensitivity. This sensitivity makes it easier for a house fire to jump to neighboring houses in comparison to materials such as brick or masonry.
An environmental cost of vinyl siding is that it is difficult to dispose of responsibly. It cannot be burned (due to toxic dioxin gases that would be released) and currently it is not recycled.
Vinyl siding is also considered one of the more unattractive siding choices by many. Although some newer styles eliminate this complaint, more widespread varieties often have visible seam lines between panels and generally do not have the quality appearance of wood, brick, or masonry. The fading and cracking of older types of plastic siding compound this issue. In many areas of newer housing development, particularly in North America, entire neighbourhoods are often built with all houses clad in vinyl siding, given an unappealing uniformity. Some cities now campaign for house developers to incorporate varied types of siding during construction.
Imitation Brick or Stone - Asphalt Siding
A predecessor to modern maintenance free sidings was asphalt brick siding. Asphalt impregnated panels (about 2 feet by 4 feet) gave the appearance of brick or even stone. Many buildings still have this siding, especially old sheds and garages. If the panels are straight and level and not damaged, the only indication that they are not real brick may be seen at the corner caps. Trademarked names included Insulbrick, Insulstone, Insulwood. Commonly used names now are faux brick, lick it and stick it brick, and ghetto brick. Often such siding is now covered over with newer metal or plastic siding. Today thin panels of real brick are manufactured for veneer or siding.
Insulated siding has emerged as a new siding category in recent years. Considered an improvement over vinyl siding, insulated siding is custom fit with expanded polystyrene foam (EPS) that is fused to the back of the siding, which fills the gap between the home and the siding.
Products provide environmental advantages by reducing energy use by up 20 percent. On average, insulated siding products have an R-value of 3.96, triple that of other exterior cladding materials. Insulated siding products are typically Energy Star qualified, engineered in compliance with environmental standards set by the U.S. Department of Energy and the United States Environmental Protection Agency.
In addition to reducing energy consumption, insulated siding is a durable exterior product, designed to last more than 50 years, according to manufacturers. The foam provides rigidity for a more ding- and wind-resistant siding, maintaining a quality look for the life of the products. The foam backing also creates straighter lines when hung, providing a look more like that of wood siding, while remaining low maintenance.
Manufacturers report that insulated siding is permeable or “breathable,” allowing water vapor to escape, which can protect against rot, mold and mildew, and help maintain healthy indoor air quality.
It is important to note that the installation of many of the insulated sidings are done with an air gap located between the siding and the wall. When there is such an air gap, the effectiveness of the R value decreases dramatically as convective losses occur between the house wall and the siding - much as a wool hat does not keep you as warm when held 2" above your head.
Metal siding comes in a variety of metals, styles, and colors. It is most often associated with modern, industrial, and retro buildings. Utilitarian buildings often use corrugated galvanized steel sheet siding or cladding, which often has a coloured vinyl finish. Corrugated aluminium cladding is also common where a more durable finish is required.
Formerly, imitation wood clapboard was made of aluminium (aluminium siding). That role is typically played by vinyl siding today. Aluminium siding is ideal for homes in coastal areas (with lots of moisture and salt), since aluminium reacts with air to form aluminium oxide, an extremely hard coating that seals the aluminium surface from further degradation. In contrast, steel forms rust, which looks ugly and can weaken the structure of the material, and corrosion-resistant coatings for steel, such as zinc, sometimes fail around the edges as years pass. However, an advantage of steel siding can be its dent-resistance, which is excellent for regions with severe storms—especially if the area is prone to hail.
The first architectural application of aluminium was the mounting of a small grounding cap on the Washington Monument in 1884. Sheet-iron or steel clapboard siding units had been patented in 1903, and Sears, Roebuck & Company had been offering embossed steel siding in stone and brick patterns in their catalogues for several years by the 1930s. ALCOA began promoting the use of aluminium in architecture by the 1920s when it produced ornamental spandrel panels for the Cathedral of Learning and the Chrysler and Empire State Buildings in New York. The exterior of the A.O. Smith Corporation Building in Milwaukee was clad entirely in aluminium by 1930, and 3’-square siding panels of Duralumin sheet from ALCOA sheathed an experimental exhibit house for the Architectural League of New York in 1931. Most architectural applications of aluminium in the 1930s were on a monumental scale, and it would be another six years before it was put to use on residential construction.
In the first few years after World War II, manufacturers began developing and widely distributing aluminium siding. Among them Indiana businsessman Frank Hoess was credited with the invention of the configuration seen on modern aluminium siding. His experiments began in 1937 with steel siding in imitation of wooden clapboards. Other types of sheet metal and steel siding on the market at the time presented problems with warping, creating openings through which water could enter, introducing rust. Hoess remedied this problem through the use of a locking joint, which was formed by small flap at the top of each panel that joined with a U-shaped flange on the lower edge of the previous panel thus forming a watertight horizontal seam. After he had received a patent for his siding in 1939, Hoess produced a small housing development of about forty-four houses covered in his clapboard-style steel siding for blue-collar workers in Chicago. His operations were curtailed when war plants commandeered the industry. In 1946 Hoess allied with Metal Building Products of Detroit, a corporation that promoted and sold Hoess siding of ALCOA aluminium. Their product was used on large housing projects in the northeast and was purportedly the siding of choice for a 1947 Pennsylvania development, the first subdivision to solely use aluminium siding. Products such as 4", 6", 8" and 10" X 12’ unpainted aluminium panels, starter strips, corner pieces and specialized application clips were assembled in the Indiana shop of the Hoess brothers. Siding could be applied over conventional wooden clapboards, or it could be nailed to studs via special clips affixed to the top of each panel. Insulation was placed between each stud. While the Hoess Brothers company continued to function for about twelve more years after the dissolution of the Metal Building Products Corporation in 1948, they were not as successful as rising siding companies like Reynolds Metals.
Pros and cons of metals versus other siding materials
- Metal sidings are very energy-intensive to manufacture.
- They do not provide insulation for the structure.
- Metals are a non-renewable resource in the sense that they are a finite resource (the earth cannot get any more of them than it already has). (However, metals are often recycled, so they are renewable in the sense of recycling.)
- They often have to be shipped long distances from point of manufacture to point of use.
- May be difficult to install due to its relatively high weight.
Despite the drawbacks above, metal siding:
- is durable,
- requires minimal maintenance,
- is fire-resistant,
- is recyclable,
- and can be very cost-effective.
- it resists rot
- it resists bugs
- it rarely gets hail damage (Steel siding is rarely damaged by hail. However, certain aluminium siding is highly susceptible to hail damage.)
- is sold to some contractors painted, on a coil, and can be manufactured on site without seams
Masonry sidings are varied (brick and stone) and can accommodate a variety of styles—from formal to rustic. Though masonry can be painted or tinted to match many color palettes, it is most suited to neutral earth tones. Masonry has excellent durability (over 100 years), and minimal maintenance is required. The primary drawback to masonry siding is cost. Precipitation can threaten the structure of buildings, so it is important that the siding will be able to withstand the weather conditions in the local region. For regions that receive a lot of rain, EIFS (Exterior Insulation and Finish Systems), have been known to suffer underlying wood rot problems with excessive moisture exposure.
The environmental impact of masonry depends on the type of material used. In general, concrete and concrete based materials are intensive energy materials to produce. However, the long durability and minimal maintenance of masonry sidings mean that less energy is required over the life of the siding.
Various composite materials are also used for siding: asphalt, asbestos, fiber cement, aluminium (ACM) etc. They may be in the form of shingles or boards, in which case they are sometimes called clapboard.
Composite sidings are available in many styles and can mimic the other siding options. Composite materials are ideal for achieving a certain style or 'look' that may not be suited to the local environment (e.g., corrugated aluminium siding in an area prone to severe storms; steel in coastal climates; wood siding in termite-infested regions). These products are normally cheaper than Stucco and Stone/Brick but has similar life spans.
Costs of composites tend to be lower than wood or masonry options, but vary widely as do installation, maintenance and repair requirements. Not surprisingly, the durability and environmental impact of composite sidings depends on the specific materials used in the manufacturing process.
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