The update eliminates the limit to one-story above grade plane for that portion of the structure located below the three-hour separation of a podium building. Without this limitation, it is now possible to design and build up to an eight-story building in which wood (IIIA) construction is used on the first five.
The three primary benefits of the IBC update to section 510.2 to builders are:
- Increase density by up to 20 percent.
- Achieve this density at a lower cost.
- Shorten time to build.
Since building in higher densities is more expensive due to construction, land costs, and lenders wary of the inherently higher risks, the option to build higher densities using higher proportions of wood construction lowers the cost as wood is generally more cost effective than concrete. Furthermore, construction techniques for concrete are more time intensive than those for wood construction, which means the building can be completed faster.
From a design perspective, there is a lot more flexibility to vary the edges—what you can do around the perimeter. For example, in the concrete you can use liner units, which are edge units that typically wrap around parking; however, they could also wrap around retail. Alternatively, you could increase the value of commercial space by achieving higher plates. Within a mixed-use project, you can create better separations between uses as well as achieve a more urban look below while creating a softer façade with more articulation for the residential units above.
By Sean Whitacre, DAHLIN
Sean Whitacre is a talented designer, project manager and problem solver with a wide range of abilities in the field of architecture. With substantial experience in all phases of the design process, from planning and schematic design to construction administration, and an expertise in 3-Dimensional design software, he is uniquely equipped. Sean has designed single-family residences, large condominium projects, high-rises, retail complexes, sales centers, community and golf clubhouses, driving ranges, entry monuments and gatehouses, both internationally and domestically.