Diamond Foods Innovation Center

Photo courtesy of Eckert and Eckert

Location: Salem, Oregon
Architect: ZGF Architects
Engineer: KPFF Structural Engineers

Designed to complement and expand an existing warehouse and shipping facility, this 7,350-square-foot office includes a partial second story and multiple double-height spaces. Walls are traditional wood-frame construction using 2-by-4 and 2-by-6 dimension lumber; the truss roof includes glulam and exposed structural tongue and groove decking; and the floors are comprised of wood I-joists with glulam in select areas. The facade is an innovative combination of Douglas-fir wood siding and heat-treated pine.

Multi-Tenant Buildings

For commercial buildings, determining allowable height and area typically includes considerations related to multiple tenants or occupancies. For example:

• Incidental uses (IBC Section 509) are those that pose greater risk of fire than the main occupancy, such as machine rooms, laundry rooms, and mechanical equipment rooms. Providing they comprise no more than 10 percent of the area of the given story and have the required fire separation, smoke separation, and/or NFPA 13-compliant automatic sprinkler systems, they are not classified as a separate occupancy for the purpose of determining allowable height and area.
• Accessory occupancies (IBC Section 508.2) do not pose the same level of risk as an incidental occupancy and therefore do not have the same dedicated passive or active fire safety requirements. To qualify as an accessory occupancy, the area must comprise less than 10 percent of the story area and the IBC 506 “NS” allowable limit value. For commercial buildings, no separation is required between the accessory occupancy and main occupancy, and only the main occupancy need be considered when calculating height and area. Examples include storage in an office or kitchen in a community space.
• Nonseparated occupancies (IBC Section 508.3) have another level of restriction in terms of fire protection systems (IBC Chapter 9) and allowable height and area, as well as other requirements based on the most restrictive occupancy of the mix. However, the advantage is that they don’t require specified fire-rated assemblies between occupancies. An example would be the same office/ storage scenario, but where the storage comprises more than 10 percent of story area. To check the allowable heights and areas of nonseparated occupancies, the nonseparated occupancies should be checked as if the entire area consists of each of the contained occupancies, with the most stringent check governing the allowable height and area of the nonseparated occupancies.
• Separated occupancies (IBC Section 508.4), as the name suggests, require fire-rated assemblies between occupancies. This separation allows for larger allowable areas than nonseparated occupancies, while allowable height is based on occupancy—i.e., the IBC allows a specific elevation or number of stories for each occupancy group. Because of this, an architect may be required to put certain occupancies on lower versus higher floors.

A good resource for height and area analysis is the 2015 Code Conforming Wood Design, a joint publication of the ICC and American Wood Council (AWC), available at www.awc.org. WoodWorks also offers a free downloadable Heights and Areas Calculator, available at www.woodworks.org, which reviews and analyzes building height and area compliance with the 2015 IBC for buildings up to six stories, with up to four occupancy groups at each level.

Big Box Retail: Wood Saves Nearly $1 Million Cost and environmental studies compare wood to steel

To evaluate the opportunity for wood use in the commercial building subcategory known as big box retail, WoodWorks commissioned two studies—one cost comparison and one life-cycle assessment (LCA)—on the same big box project designed in steel versus wood.

Having received the drawings for a one-story, 54,800-square-foot steel-frame big box store in California, WoodWorks commissioned the design of a comparable building using wood materials. Both buildings are designed according to the 2010 California Building Code, which is based on the IBC. The two designs share the same geometry, structural layout, and column grid. They also have the same gross floor area, floor plan, and layout.

According to the cost comparison, the wood building design saved an estimated 22 percent, or $988,626, compared to the steel building design. The largest cost savings were associated with the structure and roof insulation. Structure cost savings associated with the wood design totaled approximately $425,000. In order of highest to lowest savings, they were concentrated in roof framing beams, roof decking, roof framing columns, primary roof framing such as trusses and joists, and wall framing. Savings associated with roof insulation represented the largest single-element savings (more than $400,000) due to the cost difference between rigid insulation (steel design) and batt insulation (wood design).

The LCA study concluded that the impacts of the proposed wood building are lower than the steel building for all indicators except ozone depletion, where the proposed building results were 5 percent higher. Impacts were analyzed from raw materials through demolition/disposal and also with the additional stage of recovery/reuse/ recycling. Highlights through demolition/disposal include:

Global warming potential: Wood building saves 642 metric tonnes of carbon dioxide equivalent (CO₂e).

Nonrenewable energy use: Wood building saves 9,116 gigajoules (GJ).

Raw material supply and manufacturing: Wood building has an average of 30 percent less impact across all indicators.

End-of-life transport: Wood building has 11 percent less impact across all indicators.

Adding the recovery/reuse/recycle stage had minor effects on the overall comparison between the wood and steel buildings. As with the analysis excluding this stage, the wood building outperforms the steel building overall and for all indicators except ozone depletion potential, where the proposed building results were slightly higher.

Detailed information on these studies is available in the WoodWorks report, which includes a section on opportunities for big box wood design.¹

Fire Resistance and Detailing

Types I, II, III, and V Construction are further subdivided into two categories (IA and IB, IIA and IIB, IIIA, and IIIB, and VA and VB) with the difference being the degree of fire resistance required for various building elements and assemblies. For example, in Type VA Construction, all interior and exterior load-bearing walls, floors, roofs, and structural members are required to have a minimum 1-hour fire-resistance rating. In Type VB Construction, no fire-resistance rating is required.

While a detailed discussion of fire resistance is beyond the scope of this course, there are many sources for tested fire-rated assemblies. Fire-rated wood-frame assemblies can be found in publications such as:

• Underwriters Laboratories’ (UL) Fire Resistance Directory
• Intertek Testing Services’ Directory of Listed Products
• Gypsum Association’s Fire Resistance Design Manual

Fire-rated assemblies may also be selected from one of the prescriptive assemblies provided in IBC Section 721, which are based on ASTM E 119 or UL 263 test results, by calculating an assembly’s fire resistance using IBC Section 722 or by other methods indicated in Section 703.3 of the code. The AWC publication, Design for Code Acceptance (DCA) 3 – Fire-Rated Wood Floor and Wall Assemblies, also contains fire ratings of wood-frame wall and floor/ceiling/roof assemblies and is available free at www.awc.org/codes-standards/ publications/dca3.html.

BMR/ECO ATTITUDE STORE CONCEPT

Photos: Stéphane Groleau

Locations: Saint-André-Avelin, Sainte-Agathe-des-Monts, Saint-Jean-sur-Richelieu, Québec
Architect: Sophie Tétrault Architecte
Engineers: Rochon Experts-conseils S.I.M. Experts-Conseils AP Consultant

Founded in 1967 by a group of Quebecois building supply dealers, BMR seeks to incorporate regional materials into its member stores. Wood reflects the company’s heritage while its natural warmth enhances clients’ shopping experience. In addition to providing a more energy-efficient structure, an article in Les Affaires acknowledges sales increases attributable to the wood structure.