It’s a common misconception that only low-rise buildings up to two or three stories can be built with cold formed steel. Many also think that CFS is limited to small, non-critical interior or exterior framing applications. But this couldn’t be further from the truth. The structural integrity of CFS framing suits mid-rise buildings as well.
Combined with the well-known economic benefits; CFS has taken the construction industry to new horizons with faster, higher quality and more sustainable construction of residential and commercial buildings around the world.
In this article, we’ll cover the proven suitability of CFS - and its other many benefits - for taller buildings.
Why Cold Formed Steel framing grants excellent structural integrity to mid-rise projects
Cold formed steel is both lightweight and strong and is used to make durable components such as wall frames, joists and trusses. The versatility of CFS allows for lots of variations in design, taking nothing away from its strength when engineered to accepted standards.
The American Iron and Steel Institute (AISI) provides guidelines that govern the production of CFS components in North America and recognize the utility of CFS as a worthwhile structural material for common types of buildings.
While conventional wisdom has long held that structural CFS can be used for buildings up to 10 stories tall, a recent engineering analysis by the Steel Framing Industry Association (SFIA) revealed that CFS can support buildings of up to an astonishing 40 levels.
Why is this the case? The arrangement of CFS load-bearing components (which included standard C-shaped studs and typical spacings) in the feasibility study was able to meet all requirements for distribution of live and dead loads throughout the building.
This has big implications for the fast-growing urban centres of the world. While high-rise applications may be some years away still, studies such as the SFIA report hold promise for the ongoing development of multi-level residential projects in burgeoning cities using CFS.
The benefits of CFS for mid-rise buildings
A report by the Canadian Steel Construction Council summarises many of the advantages of using cold formed steel in mid-rise building construction, across several categories.
- Steel confers cost reductions in terms of the overall cost of construction. By using CFS, you can save on design, engineering and energy costs.
- Project timelines are typically reduced with CFS construction, leading to improved cash flow on the side of owners, as well as faster ROI.
- Lower risk insurance is likely, given the general safety benefits of steel over and above other materials (such as wood).
- Steel never shrinks, unlike wood, and is dimensionally stable. Steel components can be very precisely specified, and CFS is easily used in a wide variety of design configurations.
- Steel components allow for wider frame spacing and longer spans, allowing for larger and more customizable interior spaces.
- Steel is non-combustible, never burns and does not contribute fuel to fires.
- Fires, which may reach a maximum of 900°C – 1,100°C, generally cannot reach the melting point of steel at 1,500°C.
- When properly engineered, steel framing is highly ductile, absorbing the impact of seismic activity without warping.
- Steel is very commonly reused and recycled in construction applications without loss of quality.
- 97% of the by-products of steel are reused.
- The overall recycling rate of steel, taking all industries into account, is 81%.
The many benefits of steel in construction, including its superior durability and resilience, make it a worthy option for use in multi-level buildings.
Examples of mid-rise projects using CFS
Several mid-rise projects have already taken great advantage of cold formed steel as a structural material.
The Mariposa VII, a seven-storey multi-family building in Denver, Colorado, USA, is one such case study featured in our eBook, The Endless Possibilities of Cold Formed Steel Applications. The building makes use of prefabricated CFS wall panels for the top four levels of the building (supported by two levels of podium).
The entire mid-rise building was erected within a 40-day time span, with each storey taking only seven days from wall panel assembly to final detailing. Building with CFS allowed for a remarkably short project timeline, with efficient day-to-day work onsite.
Other realistic possibilities for mid-rise CFS construction include office buildings, hotels, dormitories, healthcare facilities and many more. Since larger construction projects in any part of the world benefit from the highest quality materials, as well as shortened time frames, it is worth considering CFS regardless of project type.
Cold formed steel solves many of the issues encountered by owners, developers and other stakeholders engaged in building mid-rise projects. Structural CFS meets regulatory standards, offers engineers and designers a great degree of flexibility, and takes advantage of new, improved technologies that are ready to meet the demands of 21st-century construction — even and especially when it comes to larger, multi-level buildings.