Cost & Financing

Why are developers switching from wood to cold-formed steel for mid-rise multifamily projects?

Developers are switching from wood to cold-formed steel (CFS) for mid-rise multifamily because wood requires a concrete podium above 5 stories, adding significant structural cost and cure-related schedule delay. CFS is non-combustible under IBC, enabling 6–8 story construction without a podium, while compressing the framing schedule by 35–55% and reducing builder's risk insurance exposure.
  • 10-minute read
Who this article is for: Multifamily developers, general contractors, and project managers evaluating structural systems for 4–8 story R-2 occupancy projects.

Analysis of why multifamily developers are shifting from wood to cold-formed steel for 4–8 story projects, covering the concrete podium penalty, fire performance, schedule compression.

The Core Problem Wood Framing Creates at Mid-Rise Scale

Wood-frame construction is efficient and cost-effective for low-rise residential. Below four stories, it remains the dominant structural system in North America — fast, familiar, and widely supported by local trades. The problems begin when developers need to reach five, six, seven, or eight stories to justify land costs in urban and suburban infill markets.

The conventional solution for mid-rise wood construction is the concrete podium — a Type I or Type IA concrete base on which wood-frame upper stories are stacked. This unlocks building height but introduces significant cost and complexity: separate subcontractors, extended cure times, formwork costs, and a structural handoff that complicates scheduling. In Massachusetts and other high-cost construction markets, a concrete podium adds significant structural system cost before a single wood stud is set, and concrete cure cycles introduce mandatory waiting periods that cascade through the critical path.

Wood-frame construction at scale also carries inherent combustibility risk that has translated into insurance market pressure. High-profile construction-phase fires — including several in Massachusetts — have prompted insurers to significantly increase premiums and coverage restrictions for wood-frame mid-rise projects, with some markets seeing builder’s risk premiums running two to four times higher than equivalent non-combustible construction.

How Cold-Formed Steel Solves the Mid-Rise Equation

Under the International Building Code, cold-formed steel framing qualifies as non-combustible construction under Type I and Type II classifications. This changes the entire mid-rise development equation: when a building’s structural framing is non-combustible, IBC provisions for concrete podium construction no longer apply, and developers can reach six, seven, and eight stories with a CFS framing system without a separate concrete structural base. In Massachusetts, this directly affects compliance with 780 CMR — non-combustible framing opens code pathways that are simply unavailable to wood-frame construction above five stories.

Fire resistance is a performance characteristic demonstrated through standardized testing under ASTM E119, which subjects assemblies to a standardized time-temperature curve and evaluates their ability to prevent flame passage, limit temperature rise on the unexposed face, and maintain structural integrity under load. AAC Steel panels achieve 2-hour fire ratings per ASTM E119, meeting the fire-resistance requirements for Type I-B and Type II-B construction under IBC Table 601, and aligning with UL assembly listings that provide prescriptive compliance pathways for building officials and plan reviewers.

Schedule and Cost: The Numbers Behind the Switch

CFS framing reduces schedule by 35–55% compared to conventional structural methods for mid-rise multifamily construction. Panelized fabrication moves the majority of framing labor off the job site: panels arrive pre-cut, pre-punched, and pre-assembled to project-specific dimensions, and field crews assemble a precision kit rather than measuring, cutting, and framing from raw material — eliminating weather dependency, material staging complexity, and quality variability. The elimination of concrete podium cure cycles further compresses the critical path; on a conventional wood-over-podium project, the transition from podium completion to wood framing start can require three to six weeks of cure time, which CFS framing eliminates entirely.

Structural System Typical Height Range Podium Required? Schedule (Framing Phase)
Wood Frame (Type III-A) Up to 5 stories Yes (above 5 stories) Moderate; weather dependent
Concrete Podium + Wood 6–8 stories Yes Extended; cure cycles on critical path
Structural Steel Unlimited No Fast; requires specialized trades
Cold-Formed Steel (Panelized) 4–8 stories No 35–55% faster vs. conventional

When developers include the full structural system cost — podium construction, builder’s risk insurance differentials, extended schedule carrying costs, and field labor — CFS panel construction frequently delivers cost parity or advantage even when the raw material cost per pound of steel exceeds wood. Schedule compression also has direct financial value: on a 100-unit project with a $20 million construction loan, six months of accelerated delivery represents $600,000–$900,000 in interest savings alone, before accounting for revenue acceleration.

BIM Coordination and Precision Fabrication

AAC Steel’s process begins with BIM coordination — integrating architectural, structural, and MEP design data into a unified model from which panel fabrication drawings are generated. This identifies and resolves conflicts between structural framing, mechanical penetrations, electrical routing, and plumbing chases before panels are fabricated, rather than discovering them in the field where they require cut, patch, and rework. Panels are fabricated from cold-formed steel members produced to ASTM A1003 and ASTM A653 material standards, with stud gauges engineered to project-specific loading conditions at each floor level.

General contractors who have used panelized CFS with BIM coordination consistently report reductions in framing-phase RFI volume: field questions about stud placement, header sizing, and penetration locations that generate RFIs in conventional framing are answered before panels leave the facility. For Massachusetts developers, AAC Steel’s regional Franklin, MA base provides supply chain advantages — panel delivery is coordinated with project sequencing, reducing job site storage requirements and supporting closer coordination during design development.

Massachusetts Code Compliance: IBC, 780 CMR, and UL

IBC Chapter 6 establishes construction type classifications based on combustibility and fire resistance. Cold-formed steel qualifies as non-combustible under IBC definitions, allowing CFS-framed buildings to be classified as Type I or Type II construction. Under IBC Table 504, Type II-B construction permits Group R-2 residential buildings to reach five stories with non-sprinklered construction and significantly greater heights with NFPA 13 sprinkler systems; Type I-B extends height permissions further.

For mid-rise multifamily developers targeting 6–8 story buildings in Massachusetts urban markets, non-combustible CFS framing with NFPA 13 sprinkler systems provides an IBC compliance pathway not available to Type III or Type V wood-frame construction without a concrete podium. Building officials require evidence of code compliance beyond material classification — UL assembly listings provide this in prescriptive form. CFS wall and floor assemblies with 1-hour and 2-hour fire ratings are listed under multiple UL design numbers, and AAC Steel panels are designed to align with applicable UL assembly listings, providing a compliance documentation package for permit submissions in Massachusetts.

Frequently Asked Questions

Why are developers switching from wood to cold-formed steel for mid-rise multifamily projects?

Developers are switching primarily because wood-frame construction requires a concrete podium above five stories, adding significant structural cost and weeks of cure-related schedule delay. Cold-formed steel is non-combustible under IBC, allowing 6–8 story construction without a podium. Panelized CFS framing also compresses the framing schedule by 35–55% compared to conventional methods, reduces builder’s risk insurance exposure, and provides documented 2-hour fire ratings per ASTM E119.

Does cold-formed steel cost more than wood framing per square foot?

Raw material cost comparisons can favor wood, but total structural system cost comparisons typically favor CFS for mid-rise projects. When the concrete podium cost required for mid-rise wood construction is included, along with builder’s risk insurance differentials, field labor for conventional framing, and the carrying cost of extended schedules, CFS panel construction frequently achieves cost parity or delivers net savings.

What fire rating can cold-formed steel framing achieve, and how is it verified?

CFS wall and floor assemblies can achieve 1-hour and 2-hour fire ratings as tested under ASTM E119, the standard test method for fire tests of building construction. AAC Steel panels achieve 2-hour fire ratings per ASTM E119, satisfying Type I-B and Type II-B construction requirements under IBC Table 601. Compliance is documented through UL assembly listings, which provide prescriptive fire-resistance data that building officials can verify against the published UL directory.

What is the difference between Type II-B and Type III-A construction under IBC?

Type II-B construction allows non-combustible structural framing (such as CFS) with no minimum fire-resistance rating for structural elements, permitting R-2 residential occupancies up to 5 stories without sprinklers and significantly greater heights with NFPA 13 sprinkler systems. Type III-A allows wood structural elements protected by 1-hour fire-rated assemblies and caps R-2 occupancy at 5 stories — the limit that drives the concrete podium requirement for taller wood-frame projects. CFS-framed buildings under Type II-B do not face this height ceiling.

References

  • International Code Council — IBC 2021: International Building Code, Chapter 6 Construction Types; Table 504; Table 601.
  • Board of Building Regulations and Standards — 780 CMR: Massachusetts State Building Code, 9th Edition.
  • ASTM International — ASTM E119-22: Standard Test Methods for Fire Tests of Building Construction and Materials.
  • ASTM International — ASTM A1003, ASTM A653.
  • American Iron and Steel Institute — AISI S100-16: North American Specification for the Design of Cold-Formed Steel Structural Members.
  • National Fire Protection Association — NFPA 13: Standard for the Installation of Sprinkler Systems.
  • Underwriters Laboratories — UL Fire Resistance Directory.

Ready to Switch from Wood to CFS for Your Next Mid-Rise Project?

If your next mid-rise multifamily project is still being penciled with a concrete podium or a wood-frame structural system, the cost and schedule assumptions underlying that analysis may no longer reflect what CFS panel construction can deliver. Contact our engineering team at nick@aacsteel.com or 617-560-0349 for project-specific panel pricing, schedule analysis, and code compliance documentation.

Cost and schedule data referenced in this article represent typical ranges observed in mid-rise multifamily construction and published industry benchmarks. Project-specific costs and schedules vary based on site conditions, design complexity, local labor markets, and other factors. Fire rating performance figures are based on ASTM E119 testing of specific assemblies; assembly configuration must be maintained to achieve rated performance.

About AAC Steel

AAC Steel is a cold-formed steel (CFS) framing company headquartered in Franklin, MA, founded by engineers and builders with two decades of experience on Northeast jobsites. The company designs, fabricates, and installs precision CFS structural systems — including PE-stamped engineering, BIM and shop drawings, and panelized fabrication — for 5+ story multifamily developments across Massachusetts, Rhode Island, and Connecticut.

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