What the IBC Requires for Commercial Stairs

Steel stairs on commercial projects are not complicated to scope correctly, but they do require the GC to understand what the code requires before the subcontractor can do much useful work. The International Building Code establishes the standards that govern commercial stairways in Houston, and a few of these requirements have real implications for how the stair scope is designed and bid.

Width is calculated by occupant load, not guessed. For non-sprinklered buildings, the IBC calls for 0.3 inches per occupant served by the stair. For sprinklered buildings with alarms, that factor drops to 0.2 inches per occupant. In either case, the minimum width is 44 inches. Stairways serving an occupant load of fewer than 50 can go as narrow as 36 inches.

The dimensional requirements are clear: maximum riser height of 7 inches, minimum riser height of 4 inches, minimum tread depth of 11 inches, and minimum headroom clearance of 80 inches measured vertically from the nosing line. Handrails are required on both sides of any commercial stair, mounted between 34 and 38 inches above the tread nosings. Guards at open sides must be at least 42 inches high. Tread nosings require a visual contrast marking under IBC Section 504.6, which matters for inspection and occupancy sign-off.

Each flight of stairs is limited to 12 feet of vertical rise before a landing is required. The landing width must match the stair width. These are not options or design decisions. They are code minimums that a fabricator is building to, and a shop that is working from incomplete or inaccurate field dimensions will have problems at installation.

We fabricate commercial steel stairs for tenant build-outs, renovations, and ground-up projects across the Houston metropolitan area. We handle straight stairs, L-shaped stairs with landings, curved stairs, and spiral stairs, and we work within project specifications on all of them. But the quality of what comes out of our shop is directly tied to the quality of what the GC provides going in.

What a Steel Stair Subcontractor Needs from the GC to Quote Accurately

This is where stair scopes run into trouble on commercial projects. A subcontractor cannot produce an accurate proposal for steel stairs without specific information, and that information is not always available at the time bids are being assembled.

At minimum, to quote a steel stair scope, we need:

• Floor-to-floor height (confirmed field measurement, not a plan dimension)
• The number of stairs and any landing configurations required
• Clear width requirements per the IBC calculation for that specific occupant load
• Guard and handrail specifications, including whether handrails are structural or decorative
• Tread type (grating, checker plate, concrete-filled pan, or other)
• The finish specification, whether that is prime and paint, powder coat, or galvanized

If any of these are not confirmed, the proposal is going to have assumptions built into it. Assumptions create scope disputes. We would rather ask the questions upfront than have that conversation later.

A common situation on tenant build-outs is that the GC sends plans that show stair location and a rough section, but the final floor heights have not been confirmed in the field and the tread specification is listed as "by architect" or "TBD." We can quote off the plans with noted assumptions, but we are clear about what is locked and what is not. When the details change, the price changes. That conversation is easier to have before fabrication begins than after.

How Stair Fabrication Fits Into the Project Schedule

Steel stairs are typically part of the miscellaneous metals scope, separate from the structural steel scope even when both are carried by the same subcontractor. On a tenant build-out, the structural steel goes in first. Stairs often follow in a second phase, once the structural framing is confirmed and field dimensions can be verified.

This sequencing matters for GCs managing tight finish schedules. The fabrication timeline for a standard commercial stair in our shop typically runs two to four weeks from when final dimensions and specifications are confirmed. That clock does not start until the field measurements are verified and the design is signed off. If a GC is working toward a certificate of occupancy and the stairs are on the critical path, that verification step needs to be built into the schedule, not treated as a formality.

We have worked on build-outs where the GC did not realize stair fabrication ran independently from structural steel lead times, and the oversight created a schedule problem downstream. Coordinating early about what information the stair sub needs and when they need it avoids that. It is a straightforward conversation, and it is worth having at the beginning of the project.

The other trades that typically interact with a stair scope are the drywall and finish contractors (who work around the stair opening), the flooring contractor (who needs to know the tread finish), and sometimes the mechanical or electrical teams if conduit or sprinkler heads are routed near the stair shaft. Calling those coordination points out in the early project meeting prevents interference later.

See the structural steel scheduling article for a more detailed look at how the steel scope integrates with the broader project timeline on Houston commercial projects.

Working Through a Stair Scope with A.G. Welding

We are a City of Houston certified structural steel fabricator serving the commercial construction market across the Houston metropolitan area. We handle the full stair scope, from shop drawings through fabrication and erection, and we provide detailed written proposals that spell out what is included, what the tread and finish specifications are, and what the timeline looks like from confirmation of dimensions through installation.

For GCs who are coordinating a stair scope alongside a larger structural steel or miscellaneous metals package, we can handle both. Our welding repair services are also available for existing commercial stairs that need repair rather than full replacement.

To discuss a commercial stair scope on a Houston project, contact A.G. Welding or call us directly at (713) 988-4200.