Tips for a thorough yet expeditious plan review and inspection.
The Cold-Formed Steel (CFS) has been one of the most commonly used building material in commercial buildings for decades. In spite of that, the International Building Code (IBC) is somewhat vague on the subject. Although, Chapter 22 of the IBC refers the reader to the appropriate design Standards, in most cases, the local Building Departments do not have access to said Standards. Additionally, some manufacturers have “proprietary” methods of installation for some of their components.
Coupling the above with, in some instances, spartan drawings/construction documents, could lead to longer building plan review turnaround time and/or plan review and inspection rejections.
A good way to facilitate the project approval is to ensure that the construction documents contain the necessary level of specificity and details; while at the same time, not overwhelming the plan reviewer/inspector with unnecessary information. Likewise, coordination between architectural and structural details is a must in order to avoid conflicting details.
The items below may not apply to all projects, however, they are recommended to be specified and appropriately detailed on the construction documents, as applicable.
- Size, gage, span rating and spacing of studs
- Size, gage of C-Sections (tracks)
- Size, gage, span rating and spacing of joists
- Type, size and location of required joist stiffeners
- Type, size, location and span rating of required braces/kickers
- Top of wall detail
- Type, gage and size of required deflection tracks
- Construction details for soffits and other suspended architectural features
- Type, size, gage and spacing of resilient channels
- Type, size and amount of required fasteners at each type of connection; i.e.: bottom track to slab; stud to bottom/top track; stud to deflection track; deflection track to supporting building components; brace/kicker to stud/top track and supporting element; etc.
Whilst all the items indicated above are important, specific attention will be given in this writing to deflection tracks and suspended architectural features.
Taking into account the variety of available products and the differences between products and/or manufacturers, special consideration should be given to the design/review/installation/inspection of deflection tracks. Some of the most common types of deflection tracks offered by the industry, are: slotted track; (single) deep leg deflection track; and double deflection track.
The design should recognize the two key deflection track type differences noted in the chart below; and the construction documents should specifically identify and detail the applicable condition. Intermixing the requirements between the different deflection track types will result in wall assembly failure.
View the Deflection track considerations>>
The amount of deflection needed for any given wall assembly is a very important factor; thus, the “gap” required between the top of the stud and deflection track should be specified on the construction documents so that it can easily be identified and facilitated by the contractor; and verified by the reviewer/inspector.
Often, wall assemblies are required to have a fire and/or smoke resistance rating. Not all the deflection tracks available on the market are listed for installation in rated assemblies. When the deflection tracks are part of a rated wall assembly, the construction documents should contain sufficient information to demonstrate the adequacy of the deflection track for the proposed fire/smoke resistance-rated assembly.
Soffits, Bulkheads and other Suspended Architectural Features (SBSAF)
For obvious reasons, the correct installation and/or construction of SBSAF’s is paramount to the safety of building occupants. Unfortunately, way too often the construction drawings lack sufficient details for the construction of SBSAF’s.
The construction documents should provide details for all the different configurations that may apply to the project; i.e. SBSAF’s installed parallel vs. perpendicular to the supporting building components (roof joists, rafters, trusses, etc.). Cut section details should clearly identify the type, size, gage, and spacing of all the applicable building components required for the construction of SBSAF, as well as the type, size, and the number of required fasteners at each type of connection.
The total weight of SBSAF’s is critical to the overall design. When SBSAF’s are supported by existing roof systems, a structural analysis of the existing roof system may be required to ensure the adequacy of the existing system in supporting the additional weight imposed onto it. On new construction, the weight of the SBSAF’s needs to be shown on the roof framing layout so that it can accurately be accounted for in the overall roof framing design.
Special attention should be given to existing walls converted to SBSAF’s. If the interior partition walls are continuous from slab/floor to the floor/ceiling, or roof above, a deflection track (or clips) will be utilized at the top of the wall. As such, if the bottom portion of the wall is cut off to create a SBSAF, the existing top of wall condition is critical to the overall support of the remaining SBSAF. In most cases, additional braces and supports are required. While not always possible before actual demolition/construction commencement, an effort should be made to identify existing conditions and to appropriately detail them on the construction drawings.
The overall success of a project is, in part, directly proportional with the team-like mentality and coordination between the designers, plan reviewer, contractor, and inspector.
Although the building codes throughout Virginia are Uniform (Statewide Building Code), the internal processes and policies vary amongst local Building Departments. It is recommended for designers to reach out to the local Building Departments prior to permit application and inquire as to the specificity required on the drawings. Some localities may accept less detailed construction documents while others may require information above and beyond that which is suggested in this writing.
Florin Moldovan, MCP
Code & Regulation Specialist
DHCD, Division of Building and Fire Regulations