While wood-frame construction is not new, forward-thinking developers are finding new ways to maximize density using wood-frame construction. As the country’s urban population grows, boosting density can help cities address housing shortages and affordability challenges. Wood-frame construction is a cost-effective option for mid-rise structures because it allows high density at relatively low cost, while providing other benefits such as construction speed, structural performance, design versatility and a sustainable, low-carbon footprint. You can commonly achieve five stories for many residential occupancy groups and six stories for mixed-use commercial at a fraction of the cost of concrete steel construction. And with design ingenuity, you can go ever higher.
Choosing your Multi-Story Configurations
Generally, multi-story mixed use and multi-residential projects come in one of three configurations: tuck-under, wrap around and podium. Recently, a fourth option combines light wood-frame with mass-timber to achieve additional building height. More than with other types of construction, the structural detailing of mid-rise wood buildings plays a large role in the ability to manage investment costs per unit and maximize the lot configuration. Each one offers its own advantages and opportunities to consider, along with your project’s unique needs.
Common Multi-Story Configurations
- Tuck-under/walk-up. Tuck-under units with private parking garages are common in suburban residential settings where high density is not a priority. Typically three stories, this configuration achieves the lowest densification rate, but is also the least expensive.
- Wrap-around.The wrap-around configuration consists of a centralized multi-story concrete parking structure surrounded by multiple stories of wood-frame units built from the ground up. This configuration provides accessible parking for occupants as well as security and visual appeal, since the parking structure can’t be easily accessed from outside the development or seen from the street.
- Podium. Podium construction typically includes multiple stories of light framing over a single- or multi-story podium of another construction style, which may include retail as well as above- or below-grade parking levels. Concrete podiums are the most common, though steel podiums also exist.
- Mass Timber. Although not considered ‘podiums’ under the IBC, using a heavy timber system to separate parking from light wood-frame residential units above is gaining popularity. To learn more about mass timber systems check out our Products and Systems
Six stories: MOTO is a 4-story wood-frame apartments on a two-story concrete podium. A panelized wall system allowed each level of the building to be framed in about a week.
Tips for Maximizing Density
Here are some ideas and tips to maximize the density of your next project:
- That’s a Wrap. Consider the wrap-around for urban transitional projects on the edge of cities and near transit hubs. This is a great configuration when the land is too expensive to surround buildings with surface parking but inexpensive enough to rule out underground parking structures.
- Maximize with a Mezzanine. Incorporating a mezzanine into a podium configuration can help you maximize density. The additional square footage offers the potential for more units. Popular in upper floor units, mezzanine’s can add an additional five units per acre.
- Code Savvy: Creative architects can get as many as 165 units per acre from podium construction by using grade to incorporate daylight into basements or making use of two full levels of aboveground podiums. There are number of creative designs permitted under the 2015 International Building Code (IBC) using an alternate means and methods request. To learn more check out Getting to Yes: Making Effective Use of the Alternate Means Process.
- Reach New Heights. There are a number of ways within the 2012 International Building Code (IBC) to increase residential density and overall building size. Going beyond the base heights and areas permitted for mid-rise wood is key to maximizing value. To learn more, check out our blog article in this series What’s allowed? Building heights and floor areas for mid-rise wood-frame building.
- Wood’s Urban Infill Advantage. With its flexibility and speed of construction, wood-frame construction can respond to the unique demands of urban environments, often better than other building types. These projects are often under heavy scrutiny by stakeholders who are skeptical of the impacts of building in densely populated areas. Leverage the flexibility of wood. Prefabrication can speed up construction, reduce noise during assembly and offer adaptable building types for tight complex urban spaces.
Read the next article: How to Maximize Building Heights and Floor Sizes in your Next Multi-story Project