Photo: Lawrence Anderson, www.lawrenceanderson.net Continuing Edu C a tion Stella Marina del Rey, California Architect: DesignARC Multi-Story Wood Construction A cost-effective and sustainable solution for today’s changing housing market Sponsored by reThink Wood and WoodWorks ost-effective, code-compliant and but its benefits are equally applicable to other sustainable, mid-rise wood construction occupancy types.” CONTINUING EDUCATION C is gaining the attention of design Among their benefits, wood buildings professionals nationwide, who see it as a way typically offer faster construction and reduced EARN 0.1 ICC to achieve higher density housing at lower installation costs. For example, after completing CONTINUING cost—while reducing the carbon footprint of the first phase of a developer-funded five-story EDUCATION UNIT their projects. Yet, many familiar with wood student housing project using steel construction, (CEU) construction for two- to four-story residential OKW Architects in Chicago switched to wood. structures are not aware that the International “The 12-gauge steel panels were expensive, l earning Objectives Building Code (IBC) allows wood-frame very heavy and difficult to install; and welding After reading this article, you should be able to: construction for five stories and more in and screwing the shear strap bracing was very 1. Identify the sustainability and economic building occupancies that range from business time consuming,” says project architect Eileen benefits of using wood construction for mid-rise buildings. and mercantile to multi-family, military, senior, Schoeb. “Using wood was far more economical 2. Summarize building code requirements student and affordable housing. for the second phase.” Farooq Maniar, president and provisions for mid-rise multi-family “Once designers know that wood offers all of California-based Farooq Maniar, Inc. and wood-frame structures. the required safety and structural performance structural engineer for a number of senior 3. Discuss wood framing solutions that capabilities and meets code requirements for apartment projects also finds wood construction address issues such as shrinkage, fire mid-rise, the most appealing feature of wood less costly. “The lead time and construction time protection, and seismic requirements tends to be its price,” says Michelle Kam-Biron, are far less than they are for steel.” while minimizing carbon footprint. P.E., S.E., director of education for the American Wood construction also offers advantages 4. Explore innovations in wood framing design Wood Council. “Multi-family housing was one for project teams seeking green building techniques and wood product technologies of the first market segments to rebound from certification or simply to reduce the that enhance energy efficiency. the recession—because it’s more affordable environmental impact of their buildings. Wood than single-family housing while offering grows naturally and is renewable, and life cycle To receive credit, you are required to read advantages such as less upkeep and, in most assessment studies consistently show that wood the entire article and pass the test. Go to www.awc.org for complete text and to take cases, closer proximity to amenities. Wood offers environmental advantages in terms of the test for free. construction is attractive for multi-family embodied energy, air and water pollution, and projects because it offers a high percentage of other impact indicators.1 AWC COURSE #DES515-A ICC COURSE #363 rentable square footage at a relatively low cost, From a carbon footprint perspective, wood 2 MulTI-STory WooD ConSTruCTIon Photo: Lawrence Anderson, www.lawrenceanderson.net “Wood is also versatile and adaptable,” Interior of Stella, says Kam-Biron. “Modifications on the jobsite a contemporary tend to be straightforward and are easily apartment building made.” A survey of 227 buildings demolished in Marina del Rey, California. in Minneapolis/St. Paul found that buildings are often torn down within 50 years, regardless of material, because of changing needs and increasing land values as opposed to performance issues.5 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 (with minimal additional processing)—is a significant advantage. MASTERING WOOD CONSTRUCTION DESIGN As with any other type of construction, mastering the technical details of wood-frame construction is critical to creating cost- effective buildings that are safe and durable. Building codes require all building systems to continues to store carbon absorbed during frame building and one five-story wood-frame perform to the same level of safety, regardless the tree’s growing cycle, keeping it out of the building on a shared concrete podium, has a of material used, and wood-frame structures atmosphere for the lifetime of the building— carbon benefit equivalent to 14,049 metric tons can be designed to meet or exceed standards for or longer if the wood is reclaimed at the of CO2. This includes 4,495 metric tons of CO2 (among other things) fire protection, seismic end of the building’s service life and reused stored in the wood products and 9,554 metric performance and resistance to high winds. or manufactured into other products. The tons of avoided CO2 emissions. According to The following pages will provide an overview manufacturing of wood products also results the U.S. Environmental Protection Agency’s of technical considerations related to the design, in less greenhouse gas emissions than other Greenhouse Gas Equivalencies Calculator, safety and structural performance of mid-rise materials.2 For example, according to one online this equates to emissions from 2,683 cars for a wood buildings, as well as two trends that are carbon calculator,3 the new Stella apartment year or from the energy required to operate an expanding the opportunities for wood use in complex, which includes one four-story wood- average home for 1,194 years.4 multi-story design. De nsity, Cost and PErformanCE Project: stella location: marina del rey, California Architect: designarC Engineer: Taylor & syfan Consulting Engineers Owner: merlone geier Partners Developer: gLJ Partners Size: Two buildings, 650,466 square feet (total), 244 units type of construction: IIIA and Va Year of completion: 2013 until a few years ago, it was fairly uncommon for an architect to go beyond four stories with wood-frame construction. today, many designers choose five stories of wood over concrete podiums as a way to cost-effectively increase the density of projects. “it seems that all of the newer projects here in southern California are going taller, and they’re all being built in wood,” said tony ditteaux, partner and vice president for gLJ Partners, developer and general contractor of stella. “as developers, we’re trying to maximize our height and the number of units we can get on a site. Wood allows us to do that quickly and affordably.” gLJ did a quick analysis and found that wood framing was the most cost-effective option. Prefabricating part of the project off-site—another trend—brought the costs down further, saving 1-2 months of construction time and a few hundred thousand dollars. Photos: Lawrence Anderson, www.lawrenceanderson.net MulTI-STory WooD ConSTruCTIon 33 Source: American Wood Council Building Code Requirements Residential Continuing Edu The IBC is the predominant U.S. model Long-term stay multiple-family facilities (R-2) and Short-term (R-1) building code, having been adopted by most (i.e., apartments, convents, dormitories, fraternities and sororities for R-2; hotels and motels for R-1) states with or without amendments. Chapters NFPA 13 Sprinklers 100% Open Perimeter 16, 17 and 23 cover structural wood design and construction. (Non-structural provisions such Type IIIA Type IIIB Type VA Type VB as heights and areas are covered elsewhere.) Maximum stories 5 5 4 3 The IBC classifies buildings into five types of construction. Construction Types I and Maximum building 85 75 70 60 II are generally limited to non-combustible height (ft) C a materials such as concrete and steel, although Total building area 270,000 180,000 135,000 78,750 tion wood can be used in all types of construction (at maximum to varying degrees. Type III allows a mix of permitted stories) (ft2) non-combustible and combustible materials, while construction Types IV and V can have Single floor area 90,000 60,000 45,000 26,250 (ft2) combustible building materials. Multi-story wood construction generally Total building area 114,000 76,000 57,000 33,250 (ft2), single-story falls under Types III and V. (However, Type building IV multi-story construction, also known as Total building area 180,000 120,000 90,000 52,500 Heavy Timber, is growing in interest.) Each (ft2), two-story building type is further subdivided into A and building B, which have different fire-resistance rating IBC allowable heights and areas for residential wood construction requirements, with A being the more rigorous. (See section: Fire Protection Requirements.) which provide fire-fighting access. amended to allow Type V residential buildings “From a cost perspective it makes no sense to Sprinkler systems. For most occupancy to have up to five stories of wood-frame use Type I for five stories,” says Tim Smith, AIA, groups, increases to the allowable height (and construction with additional limitations. In founding principal of Togawa Smith Martin, number of stories) and floor area are permitted Canada, the British Columbia building code Inc., Los Angeles, and a pioneer of five-story according to IBC Section 504.2 with the use was revised in 2009 to permit residential wood wood framing in California. “Type I is more of an approved automatic sprinkler system in construction up to six stories.