The combination of growing student populations and aging facilities is a challenge for many education institutions trying to create warm and enriching learning environments with limited budgets. Add the fact that many also want to set an example for their communities by meeting sustainability and low-carbon objectives, and the challenge seems immense. As a result, an increasing number of designers are turning to wood-frame construction.
Doing More with Less
Wood’s overarching benefit for many designers is that it offers the opportunity to do more with less:
•Warm learning environment. Wood can be used both as a structural and finish material, adding warmth to what could otherwise end up being a cold, institutional space. A recent study by the University of British Columbia and FPInnovations also established a link between wood and human health. In the study, the presence of visual wood surfaces in a room lowered activation of the sympathetic nervous system, which is responsible for physiological stress responses in humans. Study author David Fell says that although the study took place in an office, the results may apply to any interior environment. (A separate study on schools in underway.)
•Natural, renewable and carbon-friendly. Wood is a sustainable building material that can help schools meet green building goals. It grows naturally and is renewable. Life-cycle assessment studies, such as "Life Cycle Environmental Performance of Renewable Building Materials in the Context of Building Construction" from the Consortium for Research on Renewable Industrial Materials, also show that wood is better for the environment than steel or concrete in terms of embodied energy, air and water pollution and carbon footprint.
From a carbon perspective, the use of wood has several benefits. As trees grow, they absorb carbon dioxide (CO2) from the atmosphere. They release the oxygen back into the air and incorporate the carbon. When mature trees are harvested and manufactured into products, much of this carbon is stored in the wood indefinitely, and the regenerating forest once again begins absorbing CO2. In the case of buildings, this carbon is kept out of the atmosphere for the lifetime of the structure—or longer if the wood is reclaimed and used elsewhere. Manufacturing wood into products also requires less energy than other materials and produces less greenhouse gas emissions.
•Energy-efficient. Wood has low thermal conductivity compared with steel and concrete. However, because many factors have a greater influence on a building’s energy efficiency, the more relevant point for many designers is that wood building systems lend themselves to structures that are highly energy-efficient.
•Quick installation. No education institution wants to delay the first day of school because a project is behind schedule, so speed of construction may provide big advantages. Wood products are readily available, and most communities have large pools of skilled workers with wood-framing experience. In some cases, wood building components can be prefabricated, which improves efficiency and results in lower construction costs and faster occupancy.
•Durability and adaptability. Schools get a lot of abuse, so durability of finish materials is important. But school designers also understand the importance of balancing durability with aesthetics. For example, an exposed wood roof system may offer a durable and aesthetically pleasing environment at a cost similar to a dropped ceiling. Gypsum walls can be reinforced with wood structural panel backing to provide a durable, yet adaptable structure. 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. Wood also is well-suited to additions and retrofits, and wood systems can be dismantled and the materials used elsewhere.
The International Building Code (IBC) allows use of wood in a wide range of building types, including schools.
Type V is the most common type of wood construction and is allowed for school design. One-story Type V schools may be up to 87,875 square feet, and two-story Type V schools may be as large as 138,750 square feet. Allowable areas may be exceeded by using two-hour firewalls.
Designers accustomed to working with steel or concrete often design buildings using Type IIA or IIB construction. However, nearly identical height and areas can be achieved with wood framing in Type IIIA or IIIB buildings.
In Type III construction, untreated wood is permitted in roof and floor systems and can be used to frame interior walls. Wood can be used in exterior walls where fire-retardant-treated (FRT) lumber and plywood is specified.
Type IV heavy timber is allowed in the roof structure and for secondary members in Type I and II construction. Wood often is used to add visual appeal in libraries, gyms, cafeterias and other common spaces.
Building codes require all building systems perform to the same level of safety, regardless of material used. Wood-frame construction has a proven safety and performance record for fire protection, and the addition of sprinkler systems, fire resistance-rated wall and floor/ceiling assembles and open spaces around the building can be used to increase the allowable size of wood-frame structures. Most local building codes require sprinkler systems and other means of fire protection in school construction, regardless of the type of framing.
Sidebar: Fountain Lake School District, Hot Springs, Ark.
When Fountain Lake School District in Hot Springs, Ark., needed a new middle school and renovations to an existing high school, it started down the "business as usual" path with a structure designed in masonry and steel. But initial estimates for the combined 63,362-square-foot project came in over budget, at $150 per square foot.
The district’s design team decided to consider wood framing. Bids for a wood-frame, two-story middle school and high school renovations came in at $107 per square foot, saving the district $2.7 million.
Sidebar: El Dorado High School, El Dorado, Ark.
The new 320,500-square-foot El Dorado High School was a big deal for the small town of El Dorado, Ark. A generously funded scholarship program was expected to increase high school enrollment beyond capacity of the 1960s-era facility, and the old school was inadequate in both safety and space. Although projects of this size commonly would be designed in steel and masonry, initial building estimates came in $50 per square foot higher than budget. So, the design team considered other framing options, and found savings with wood.
Wood framing saved the district $2.7 million in project costs. The state-of-the-art high school features exposed wood in open spaces, including single-span, 165-foot glulam bowstring trusses in a 2,200-seat basketball arena. Wood framing also is featured in the main corridors and the commons/dining area.
The school was designed by CADM Architects and completed in 2011.