CASE STUDY: MOTO

Photo: Ryan Gobuty | Architecture: Gensler

At MOTO, the panelized light-frame wood wall system created a dramatic speed of construction that allowed each level to be framed in about a week and the entire project in less than a month, making the project viable for the developer.

Photo: Ryan Gobuty | Architecture: Gensler

The massing of the wood-frame apartment building is what makes it distinctive; each level slides 2 feet away from the level below, revealing a cedar soffit on the exterior that creates a unique experience as one moves around the building.

Denver, Colorado

MOTO is an 82,000-square-foot, Type VA mixed-use, 64-unit apartment building with integrated parking and retail that is located in a Denver area known for its rich cultural, artistic, and musical offerings. The four-story, light-frame wood structure is set over a two-level concrete podium with above-grade parking, and 3,000 square feet of retail space is anchored by two tenants that were selected to work with the theme of the neighborhood and building. One is an old-time barber shop, and the other is a coffee shop/restaurant that serves small dishes and drinks in the evening. With Denver becoming a workforce destination, this project addresses the growing desire for more compact housing with shared amenities.

Wood was used both as the structural material and a design element that sets the building apart from its contemporaries. The massing of the wood-frame apartment building is what makes it distinctive; each level slides 2 feet away from the level below, revealing a cedar soffit on the exterior that creates a unique experience as one moves around the building. The bathrooms, kitchens, and corridors stack in plan, but the remainder of the apartments move with the 2-foot shift as opposed to traditional apartment stacking with flat vertical facades. This means the bedrooms on the exterior wall undulate in and out, with every other unit having more area than the other.

The panelized light-frame wood wall system created a dramatic speed of construction that allowed each level to be framed in about a week and the entire project in less than a month, making the project viable for the developer. Structural materials include a combination of dimension lumber, I-joists, and laminated veneer lumber (LVL), while wood finishes include cedar tongue-and-groove soffits, a cedar trellis that wraps down the facade and pool deck railings, pine slab doors in every unit made from trees killed by the mountain pine beetle, and reclaimed veneer pine at the lobby accent wall. The podium is board-form concrete.

According to Nick Seglie, architect at Gensler’s Denver office, “One of the major benefits we saw with wood construction on the apartment levels was that we utilized a prefab wall system. They built the walls off-site and brought them on-site. That allowed each floor of the residential units to be framed in about a week. The podium took about four weeks to construct and then an additional four weeks until we were framed out, which was great.” Also, “Wood provides a lot of benefits as a construction project because it is easy to work with, fast, and sometimes less expensive. From a design standpoint, we like to bring it in projects as a finish material whenever possible to create warmth.”

Prefabricated Wood Construction

Prefabricated wood buildings are no longer limited to single-family housing and smaller temporary workspaces but are now being constructed for innovative buildings demanded by tenants and owners. Sectors with redundancies, such as multifamily housing (e.g., condos, student housing and senior housing), education buildings, commercial retail, health-care, and institutional buildings, are more likely to be built prefabricated.

Image courtesy of StructureCraft

Computer numerical control machining technology is used at the plant to profile wood panels for installation, and sophisticated connection systems with a high degree of accuracy and efficiency are incorporated during prefabrication.

Wood has many benefits to the building industry, including aesthetics, environmental performance, strength and rigidity, lighter weight (compared to concrete), and energy efficiency. In prefabricated buildings, wood is particularly beneficial; it has the structural simplicity needed for cost-effective projects and design versatility, and it can be rapidly installed with reduced waste.

Prefabricated wood wall and floor panels offer easy handling during construction, and a high level of prefabrication facilitates rapid project completion. This is a key advantage, especially in midrise construction from five to 10 stories. Lighter wood panels mean that foundations do not need to be as large and smaller cranes can be used to lift panels higher. For example, at the four-story John W. Olver Design Building at the University of Massachusetts Amherst, four 60-foot-tall cross-laminated timber (CLT) panels comprising one of the building’s shear wall cores were lifted and dropped into place with a crane and anchored to the foundation, all in one weekend.

Panelization means framing of dimension lumber or mass timber walls produced with a high degree of accuracy in a factory. Computer numerical control (CNC) machining technology is used at the plant to profile wood panels for installation, and sophisticated connection systems with a high degree of accuracy and efficiency are incorporated during prefabrication. Panelizing lowers cost and speeds up the delivery of walls to a site where framing crews install quickly when compared with on-site framing. The faster and safer contractors and developers can finish a building, even if off-site construction methods are more expensive, the greater the return on investment. For light wood-frame construction, on-site framing is still the norm because it continues to make sense from a quality vs. cost perspective, but that is slowly changing. In the future, larger projects that demand panels be erected quickly and en masse are more likely to be prefabricated for light wood-frame construction.

Types of Wood Prefabrication

There are two types of industrialized approaches to prefabricated buildings: building kits (kit of parts) and finished modules. Building kits include prefabricated elements or sections that are then delivered and assembled on-site. These may include the roofing package (roof panels, fascia, gutter, etc.), roof structure (ceiling deck and beams), glazing package (windows and entrances), and building structure (wall panels, beam pockets, columns and shear paneling). The kit-of-parts approach, via panelization, is typical for midrise wood buildings.

Image courtesy of LEVER Architecture

Building kits include prefabricated elements or sections that are then delivered and assembled on-site. The kit-of-parts approach, via panelization, is typical for midrise wood buildings.

Within panelization, it is helpful to understand the difference between open structural panels vs. closed structural panels. Open structural panels are a preassembled wall framework that is later fitted with other elements, such as insulation, exterior cladding, and weather barriers on-site. While this aids in time savings and flexibility, there is still a lot of site work involved. By contrast, closed structural panels are complete preassembled wall panels that may include windows, doors, plumbing, ducting, electrical, finishes, etc. Closed structural panels are larger and heavier so a crane is typically needed for on-site assembly.

Finished modules, on the other hand, are an entire building delivered and assembled on-site. Individual modules are joined together to make a single building. They are built in a factory, transported to the site, and when on-site, the modules can be placed side by side, end to end, or stacked, allowing a wide variety of configurations and styles in the building layout. Finish levels on modular units leaving the factory generally include plumbing, electrical, paint, flooring, fixtures, cabinets, and appliances. After the modules are craned into place, licensed sub-trades make electrical, plumbing, mechanical, and structural connections before finish work is completed and the building is prepped for occupancy.