01 Feb Mixed Use Design and Construction Requirements | Fire Separation
Fire separation construction for design of mixed use buildings is a requirement.
This post is a continuation of PART 1 | Mixed Use Construction Requirements.
Local Zoning Regulations are Important
When determining the required fire resistance of separating walls, it is important to remember that your due diligence is not complete at code analysis. For example, some cities may require sprinkler systems while the International Building Code may not.
Parking requirements and impervious surface ratios will limit building footprint. Building Codes of Metro Nashville typically require 10% or more impervious area (grass, flower beds, gravel, etc.) As a result, meeting target occupancy may require additional stories, potentially changing the Construction Type.
While CMArchitects offers zoning reports and zoning analysis for our clients, every project is unique. We ALWAYS recommend understanding your local codes.
Fire Resistant Construction and Separating Walls
Remember, deciding the Occupancy Classifications and Construction Type are important in determining the required Fire Separations.
A fire-rated assembly is a type of wall construction that has been laboratory tested for fire-resistance and smoke protection.
The laboratory tests are measured in time – for example, how many minutes can the wall hold up in a fire before it fails? The details are accredited by American National Standards Institute (ANSI) and UL Standards are known by most industry professionals.
Basics of Fire Separating Walls
- No corners and offsets at fire separating walls. If you see the direction of the separating wall change or turn, instead of being a straight line, you can assume increased labor, oversight and cost.
- It can be costly and difficult to detail the wall corners, as well as the intersections between the walls and the floor and roof framing. (See Plan Diagram)
- The exception to this is Fire Stairs. While required, we believe the location of the fire stair should be used strategically to minimize construction costs at Structure and Circulation.
- Floors and roofs at horizontal separations. If you plan to separate two distinct occupancy uses by floors (for example: 1st floor business, 2nd floor residential) the floor will be required to have a fire-resistance separation.
- Depending on the separation requirements of the two spaces, horizontal separations are more labor intensive and require more detailing than vertical separating walls. (See Elevation Diagram)
- Details for horizontal-to-vertical connections at the fire separating construction. The most difficult wall to construct is a horizontal separation that turns into a vertical separation.
- Special attention should be given to the design of the floor system, more importantly the joining of the horizontal and vertical fire-rated assembly, in order to minimize labor and material cost. This can include shell, structure and interior partitions.
Keep in mind this does not include local zoning requirements, site constraints or a budget. It is every architects job to juggle the construction cost and design decisions. Our project example in the Germantown neighborhood of Nashville is an analysis that stemmed from developer driven questions.
At CMArchitects, we offer zoning analysis and zoning reports. We have extensive knowledge of which assembly configurations are typical for our contractors, as well as how to design the building such that construction is less labor intensive and less costly.
Author: Brent Hunter