- Code Acceptance
- Fire Protection
- Seismic Performance
- Wind Resistance
- Sustainable Design
El Dorado High School – El Dorado, AR
CADM Architecture • Engineering Consultants, Inc. • Completed 2012
For this 300,500-square-foot high school, the project team saved $2.7 million by switching from the original steel, concrete and masonry design to wood framing. Read the case study.
Emory Point – Atlanta, GA
Cooper Carry and The Preston Partnership • Ellinwood + Machado LLC and Pruitt Eberly Stone, Inc. • Completed 2012
For this mixed-use project, which includes one five-story wood building over slab-on-grade and three four-story wood buildings over concrete podiums, the project team saved approximately $8 per square foot for the structural frame portion of the project. Read the case study.
Big Box Retail – Wood and Steel Comparison – CA
In this comparison of wood and steel building designs, wood was able to meet all of the same performance criteria as steel for a 54,800-sf big box store in California while saving nearly $1 million.
Applewood Pointe of Langdon Lake – Roseville, MN
JSSH Architects • Blanchard Engineering • Completed 2011
Wood proved to be an affordable solution for Applewood Pointe, a high-end, 123,964-square-foot senior housing project in Minnesota. Operating under a tight budget, wood accounted for a base cost of less than $80 per square foot, offering flexibility, affordability and speed of construction. The 48-unit, four-story structure was completed in just 11 months, during the winter season. Read the case study.
Compared to conventional steel joist metal deck systems, all-wood and hybrid roof systems can save contractors up to $1.50 per square foot—which is significant when you consider that panelized roof systems are typically used on large structures such as warehouses and big box stores. For examples of savings on specific projects, read the case study.
- Visit the Building Types section of this site for code-related information on multi-residential/mixed use, education, office, commercial low-rise, industrial, civic/recreational and institutional/healthcare buildings.
- Use the Heights and Areas Calculator to review and analyze height and area compliance with the 2015 International Building Code for buildings up to six stories, with up to four occupancy groups at each level.
- Visit the Building Systems section of this site for code related information on mass timber/CLT, panelized roofs, light-frame construction, and timber-frame systems.
- Look under Design Topics for resources related to structural design and fire and life safety.
Wood’s design flexibility makes it suitable for a wide range of building types and applications, both structural and aesthetic.
Versatile – Wood can be used in many types of buildings, from single-story homes to condominiums, multi-story offices, schools, industrial facilities, recreational centers and arenas. It is suitable not only as a finish material, bringing warmth and natural beauty to interior and exterior applications, but as a structural material, offering a cost-effective way to meet code requirements for safety and performance.
New and Innovative Uses – Advances in wood science and building technology continue to expand the opportunities for wood construction. Cross laminated timber (CLT), parallel strand lumber (PSL), glued laminated timber (glulam) and prefabricated paneling systems are among the products contributing to a wider range of wood buildings.
Adaptable – Wood’s light weight and workability make it easy to apply to specific applications. With the exception of major members that are made to spec off-site, wood can be adapted in the field, allowing quick solutions if changes are required. Wood is also well suited to additions and retrofits, and wood systems can be dismantled with relative ease and the materials used elsewhere.
Ease of Construction – Building with wood, whether custom or prefabricated, is fast and efficient, and can be undertaken year-round in almost any climate. Experienced wood contractors are widely available, and workers of varying skill levels can quickly learn wood construction techniques.
Designing for Fire Protection
Building codes require all building systems to perform to the same level of safety, regardless of material—and wood-frame construction is readily accepted in the International Building Code (IBC). For example, traditional light wood-frame construction with plywood or OSB sheathing is accepted for a wide range of applications, including five-story multi-residential/mixed-use. To maximize a project’s allowable size, a designer’s options include protected construction, heavy timber construction and the use of fire-retardant-treated construction.
Also important is the fact that some wood products, such as the large beams used in heavy timber and mass timber construction may perform better in a fire situation than non-combustible materials. Because they are thick and solid, these products char at a slow and predictable rate. This char protects the wood from further degradation, helping to maintain the building’s structural integrity and reducing its fuel contribution to the fire, which in turn lessens the fire’s heat and flame propagation.
Designing for Seismic Performance
Although wood buildings are known to perform well in earthquakes1, proper detailing is essential. To this end, a basic understanding of how lateral loads impact wood framing systems and how construction detailing and fasteners affect the ultimate performance of a structure is invaluable.
Forces in an earthquake are proportional to the structure’s weight and wood is substantially lighter than other major building materials. The fact that wood buildings tend to have numerous nail connections is another benefit as it results in more load paths and better redundancy, so there’s less chance the structure will collapse should some connections fail. This is also why wood buildings have inherent ductility, which allows them to dissipate energy when faced with the sudden loads of an earthquake.
- For more information and links to technical resources, visit the Structural Design section of this site.
1The January 17, 1994 Northridge, CA Earthquake An EQE Summary Report, March 1994;
Seismic Safety Inventory of California Public Schools, California Department of Government Services, 2002
Designing for Wind Resistance
The elements of a wood-frame building that enable it to withstand lateral loads are the shear walls and diaphragms. In order to be effective, all of the related components—including framing, structural panel sheathing and inter-element fastening details—must be designed and installed correctly.
For the structural system to work as intended, the roof diaphragm must be able to transfer lateral loads to the shear walls and the shear walls themselves must transfer these loads to the foundation. The success of the entire system is only as good as the quality and quantity of the connections. Therefore, the key to constructing a building that can resist lateral loads is understanding how forces are transferred and how to design and install proper connections.
In hurricanes, the loss of roofing materials and sheathing is a leading cause of structural failure in wood-frame buildings. The most common reasons behind these failures are improper connection detailing between structural systems and inadequate fastening of sheathing to supporting members.
With proper design and maintenance, wood structures can provide long and useful service lives equivalent to other building materials. The key is careful planning and understanding of environmental loads and other external factors likely to impact a building over its lifetime. This involves four main methods of control:
- Air and moisture control
- Control of insects and other living organisms
- Use of durable materials
- Quality assurance
For detailed information, including recommendations for preventing damage from moisture and living organisms, click the Resources tab at the top of this page. However, while durability is crucial to the design of any structure, designers should be aware that many buildings are demolished before the end of their useful service lives. A survey of buildings demolished between 2000 and 2003 in Minneapolis/St. Paul demonstrated that buildings in North America often fail to make the 50-year mark, regardless of material, because of changing needs and increasing land values as opposed to performance issues. Overall, wood buildings in the study had the longest life spans, showing that wood structural systems are fully capable of meeting a building’s longevity expectations. However, when you consider the embodied energy in demolished buildings and the implications of material disposal, the fact that wood is adaptable either through renovation or deconstruction and reuse is a significant advantage.
The choice of products used to build, operate and renovate structures has a significant impact on the environment. When specifying any material, it’s important to consider its life cycle environmental impacts. Wood products have less embodied energy, are responsible for less air and water pollution, and have a lighter carbon footprint than other commonly used building materials. Wood can contribute to a building’s energy efficiency, and is thought to have a positive impact on the health and well-being of occupants. The fact that it is durable and adaptable also creates opportunities for renovation, re-use and recycling.
Click the links below for more information and references.