To maximize the value of your multi-story project, you need to use code provisions to go beyond the base heights and areas permitted for mid-rise wood-frame buildings. There are a number of ways within the International Building Code (IBC) to increase the size of wood buildings.
Upgrade your Fire Protection to Boost Height and Floor Size
Use a National Fire Protection Association (NFPA) 13-compliant sprinkler system to boost your allowable height by 20 ft and one story (IBC Section 504). By adding sprinklers, you can also increase the allowable floor area for mid-rise by three times the tabulated area (IBC Section 506).
Add a Mezzanine to Increase Overall Livable Space
Adding a mezzanine to Type III and Type V buildings can add an additional level to your project. Mezzanine’s can be up to one third of the floor area of a room or space where it is located and must be open to the room below. It is a virtual floor and is not counted in the allowable floor area. Mezzanines are particular attractive for residential projects, giving units an open airy design and market cachet. To learn more about mezzanines and other opportunities check out Getting to Yes: Making Effective Use of the Alternate Means Process.
A mezzanine is a great way to boost your density, and can add an additional five units per acre. The award-winning project, The Brooklyn Riverside, makes use of a mezzanine to increase the size of this fitness centre for residents.
Get Creative to Boost Allowable Square Footage
In addition to adding a mezzanine, work within the constraints of the relevant building code to maximize your density and floor size. For example, the base tabular floor area for Type V-A buildings with R-1 or R-2 occupancies is 12,000 square feet per story. However, if the design also meets the provisional requirements based on sprinklers and open frontage, you can increase that up to 45,000 square feet per story. For a Type III-A buildings you can boost that to up to 90,000 square feet per story.
Read the next article: How a Podium Design Can Maximize Value on your Next Multi-Story Project