Wood has long been the go-to framing choice for residential and commercial buildings-most often Type V and Type III construction-due to its cost and ease of assembly. Typically, nail-assembled, light-frame construction uses a repetitive combination of dimension lumber, I-joists, trusses, structural composite lumber, and oriented strand board decking and sheathing for floors, walls and roof decks.
While mass-timber structures are often built off site as components and assembled at the project site, light-frame construction typically occurs entirely on site. Increasingly, elements of light-frame buildings are fabricated off site and assembled on the job. Off-site construction offers greater control over construction conditions and improved safety oversight while contributing to faster construction timelines.
There are several types of light-frame construction, each suited for specific applications:Platform
This is the most common form of light-frame residential construction today due to its relative ease of building.
Platform construction sees individual floors framed separately. The walls of the story beneath each new level bear the load. The rim board transfers lateral and vertical loads, and is typically made of structural composite lumber. Framing members are typically spaced between 12 and 24 inches on-center.Balloon
Popular in industrial and retail applications, balloon frames see vertical structural members extend from the foundation to the rafters, typically two stories.Semi-Balloon
Often used for multistory projects due to its fire-management abilities, semi-balloon framing sees floors suspended from the double top plates of the walls below them, with the walls stacked.
This approach limits shrinkage throughout the building, though it requires more hardware than other framing types. Framing members are typically spaced between 12 and 24 inches on-center. Semi-balloon framing is an alternative to platform framing for Type VA and Type IIA buildings. Plank and Beam
Historically used in heavy timber buildings, plank-and-beam construction has since been adapted for residential buildings.
It uses less wood than platform or balloon construction by spacing larger wood members more widely. This type of framing sees 2-inch subfloors or roofs on post- or pier-supported beams spaced up to 8 feet. Additional framing allows for interior and exterior cladding and finishes.Truss-Framed
This type of light-frame construction employs wood systems made up of roof and floor trusses, and wall studs for additional strength and the advantages provided by off-site fabrication.
Truss-framed systems also boast greater resilience, making them particularly well-suited for areas that experience high winds. Spacing of 24 inches between frames is possible. A lack of headers, floor beams and interior columns contributes to material and cost savings. .Advanced Framing
Designed to maximize material efficiency, advanced framing techniques can be an economical option for creating durable structures that meet today’s stringent energy codes.
The construction framing techniques that define advanced framing include using 2×6 wood studs placed 24 inches on-center, the use of single top plates and headers, and wood panel sheathing for additional structural support.Light-Frame Gets Taller
The use of concrete-and-steel podiums allows light-frame construction to be used for mid-rise buildings.
This helps project teams effectively and economically respond to the growing demand for high-density, mixed-use structures featuring office or multifamily residential space atop ground-level retail and dining. Grocery-anchored residential developments are particularly popular and can benefit from the ability to erect multiple stories of wood-framed construction atop a one- or two-story concrete or masonry podium.
Updates in the 2015 International Building Code (IBC) allow for multistory podiums, making it easier for project teams to accommodate ground-floor anchors such as grocery and other retail. Previous versions of the IBC require exemptions from local authorities in order to build more than a single-level podium, and those may still be required in jurisdictions adhering to earlier versions of the code.