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Housing in the Americas

David Tilotta and Michael Lee
Wood Products Extension, North Carolina State University
Wood Products Extension

Safe, comfortable, and affordable housing is a basic human desire, and the purchase of a home is the single biggest investment that many make in their lifetimes.  Thus, the pursuit of quality, durable housing is important for not only personal reasons, but also financial ones as well.  In this article, we take a brief look at wood-frame housing in the Americas. Wood has been used as a structural and decorative material in housing for hundreds of years, and as new materials have been developed, e.g., steel, plastics, concrete, etc., wood is still an effective competitor.

Housing in the Americas 

 
Housing construction types vary widely across the Americas. In South America, the bulk of homes are constructed from concrete and brick, and wood-framed homes are rare.  In contrast, housing construction in North America relies heavily on wood.  In fact, housing construction is one of the largest uses of forest products in North America. According to the National Association of Home Builders (the NAHB) for example, the average American home of about 2,100 ft² contains just over 13,000 board feet of framing lumber, more than 6,200 ft² of sheathing, and around 2,300 ft² of exterior siding.  Of the estimated 18 million new homes that will be built in America over the next decade, the majority of them will use wood-frame construction and a variety of wood-based products. Thus, the increased demand for wood and related materials in new construction is expected to continue, as well as a corresponding increased demand for wood products in the repair, remodeling, and renovation construction industries.

As stated previously, wood is not used extensively in homes in South America.  Rather, the major building components are clay, brick, and/or concrete.  The use of these materials is chiefly due to safety reasons to avoid structural damage from earthquakes.  However, wood is still used in some homes (principally those considered to be “higher end”) for secondary applications such as doors, stairs, ceilings, and some mouldings.

Wood in Housing

Wood is used in a variety of places in a typical North American house.  The bulk of the wood is hidden in the framing and accounts for the vast majority.  Additionally, wood is used in the cabinetry, decorative mouldings, and other places.  However, this wood accounts for a minority relative to framing usage.

The bulk of the framing wood used in housing is softwood (conifers).  Additionally, softwood is used for doors and mouldings in most homes.  Softwood species routinely used include pine, spruce, and fir.  The reason for this is that softwood is easier to work with from both a cutting and fastening standpoint. Hardwoods, such as maple, oak and other species, are more difficult to cut and machine, and fasteners, while available, are more difficult to apply.  Typically, hardwoods are used for architectural millwork such as fireplace mantels and for floorings and cabinetry.

Prior to about 1940, most of the wood used in housing was solid wood – that is, wood of solid composition that was not mixed. Plywood was introduced into housing construction around 1940 and quickly became a standard over the previously used tongue and groove boards for sheathing, decking, etc.  As the name implies, plywood is comprised of layers of material (in “plys”) that are glued together with waterproof adhesives.  Because plywood is not natural and contains a mix of wood (and often a mix of species), plywood is an example of an engineered wood product.  Other engineered wood products include oriented strand board (OSB), glued laminated beams (glulams), I-Joists (so named because their cross sections resemble the English letter “I”), medium density fiber board (MDF), open-web trusses, and others.  Engineered wood products have advantages in housing construction because their properties (e.g., strength, dimensions, etc.) are often more precise than those of solid wood products.  Also, engineered wood products are available in a variety of lengths that can exceed those obtainable from natural solid wood.

Important Topics in Housing 

Major issues currently affecting or impacting housing are summarized below:

·        Green (or sustainable) building.  Green building is a trend that promotes the design, construction, operation, and renovation of structures that maximize the efficiency of their water, energy, and material use.  Such increase in efficiency has significant positive impacts with respect to environmental and human concerns including water and energy pollution, air quality, and waste management.  In the U.S. alone, buildings account for 39% of total energy use, 12% of the total water consumption, 68% of total electricity consumption, and 38% of the carbon dioxide emissions.   Wood is considered to be an environmentally friendly material because it is renewable and transformable into building materials without generating either voluminous or hazardous waste.  Ultimately, wood embodies sustainability by meeting today’s needs, without compromising the ability of future generations to meet their needs.

• Affordable housing.  Although not directly related to wood utilization, affordability issues surrounding housing are globally important and deserve mention here.  There are many definitions for affordable housing.  For example, one definition states that an affordable house should require no more than 30% of a household’s annual income.  However, a useful and simple definition is that an affordable house is a house with a price point that allows an individual desiring it to be able to purchase it.

• Durability. Durability refers to life expectancy, and in this case, the life expectancy of the materials used in the construction of homes.  Durability issues include the development of more robust and lasting preservatives, paints, coatings, and other materials to extend the service life of wood.  Additionally, the durability of wood can be improved by using it properly.  For example, including air gaps in wood framing (where appropriate) minimizes decay because it promotes drying.

• Disaster resistance.  No matter where a house is built in this world, natural disasters will test the limits of its design and construction.  Man has always created shelter in one form or another to protect life and property, and today wood products continue to be a key component in the battle against Mother Nature.  Whether the threat comes from high winds, flooding, snow, or seismic forces, wood is a contributing factor to a home’s disaster-resistance.  Its remarkable strength comes in a lightweight form.  Wood provides the flexibility needed to withstand varying forces by bending under pressure.  A home’s joists, studs, rafters, and sheathing work in conjunction with the rest of the house systems to form a protective envelope against the elements.  Wood utilization has moved beyond traditional wood-frame construction practices to include novel developments such as reinforced sheathings, structural insulated panels, and wood even helps to create safe rooms in today’s homes.

• Lumber importing and exporting. The global exchange of lumber is not only a significant issue, but also one that frequently polarizes opinions because of the effect it has on the price of wood products and who receives the benefits of trade and who pays the costs.  The most significant wood transportation and exchange in the Americas are between Canada and the United States (European wood is also freely exchanged to the Americas but will not be discussed here).  Currently, about 1/3 of the lumber in the US is softwood from Canada.  Thus, Canadian timber producers (mostly the government) and wood products manufacturers receive most of the benefits of exports, along with U.S. retailers and consumers.  On the other hand, U.S. timber producers and wood products firms and Canadian retailers pay most of the costs.  The adversely affected interest groups thus often oppose trade.

• Responsibly Managed Forests. Across the globe, more and more citizens are becoming aware of the need for responsibly managed forests.  This attitude and belief is beginning to manifest itself as the desire to construct homes using wood that comes from such forests.As a consequence of the need to foster forest stewardship, wood is now being certified for use by several organizations such as the Forest Stewardship Council (FSC) and the Sustainable Forestry Initiative (SFI).  Certified lumber is guaranteed by a third party organization, based upon internationally agreed upon principles, to have been obtained from a forest that has been responsibly managed.  The principles of responsible management include the respect for indigenous people’s rights, the fostering of strong community relations and workers rights, the minimization of environmental impact, etc.

In conclusion, housing in the Americas will always be important because it is one of the basic needs along with food, shelter, clothing, and security. In Latin America, wood is only a minor structural component of housing, but it is still widely applied and revered for trim. In North America, wood is the most pervasive material used in housing for structural applications, and equally valued for interior trim and aesthetics.

Useful Reference Links for Further Information

American Forest & Paper Association:  www.afandpa.org
American Wood Council:  www.awc.org
National Hardwood Lumber Association:  www.nathardwood.org
Wood Products Council:  www.woodinfo.org
Cabinet Makers Association:  www.cabinetmakers.org
The Wood Flooring Manufacturers Association:  www.nofma.org
Wood Moulding & Millwork Producers Association:  www.wmmpa.com
Federal Emergency Management Agency:  www.fema.gov
National Association of Home Builders:  www.nahb.org


Dr. David Tilotta and Mr. Michael Lee are with the Wood Products Extension Program at North Carolina State University, PO Box 8003, Raleigh, NC, USA27695