# Prefab Metal Stairs: Welded vs. Mechanical Systems If you're shopping for a metal staircase, you'll quickly run into two main options: welded and mechanical (also called bolted) systems. Both are prefabricated — meaning they're manufactured off-site and arrive ready to assemble — but they're built differently and suit different situations. Here's what you need to know to choose the right one. ### What Is a Prefabricated Metal Staircase? A prefabricated metal staircase is manufactured in sections and shipped to your home or job site ready to put together. You receive all the components, including stringer, treads, brackets, and hardware, in clearly labeled packages. Because the heavy fabrication work is done before it arrives, assembly is significantly faster than building a staircase from scratch on-site. The structural backbone of these systems is one or more metal stringers: the long diagonal member that supports the treads. Depending on the system you choose, everything attaches to that stringer either through welding or mechanical fasteners.

A prefabricated metal staircase (FLIGHT Mono) by Viewrail

### The Two Types of Prefab Metal Stairs #### Welded Stair Systems In a welded system, critical connection points are fused together during manufacturing. These typically include: * Tread brackets (or tread pans) to the stringer(s) * Header plates to the stringer * Footer plates to the stringer * Railing connections to the tread or stringer Because the joints are made at the factory, the unit arrives fully prefabricated and professionally welded. The tradeoff is that it ships as a larger, heavier unit — which can be a consideration depending on your site access.

A welded stair system (Not by Viewrail)

#### Mechanical (Bolted) Stair Systems Mechanical stairs use bolts, screws, and precision-engineered hardware to connect the components. The stringer ships separately from the treads and brackets, which reduces the risk of shipping damage and makes the pieces easier to maneuver into tight or finished spaces. On-site, you bolt everything together without any welding equipment or specialized fabrication skills. The result is a clean, modern finish with a straightforward installation process.

A mechanical FLIGHT Mono system by Viewrail

### How Do They Compare? | | Welded | Mechanical | | ----------------------- | ---------------------------------------------- | ------------------------------------------ | | Finish | Seamless, no exposed hardware | Clean, modern finish | | Shipping | Ships as a fully prefabricated unit | Stringer and components ship separately | | On-site assembly | Minimal, arrives fully assembled | Bolted together on-site, no welding needed | | Special skills required | May need certified welder for any on-site work | No welding needed | | Code compliance | Both meet applicable building codes | Both meet applicable building codes | Both systems include the same core components (stringer, header plate, footer plate, and tread brackets), and both must meet the 4-inch sphere rule for baluster spacing and specified load requirements. #### A Note on Customization It's a common assumption that welded stairs offer more design flexibility than bolted ones. But in practice, customization depends far more on the manufacturer than the connection method. Many standard welded prefab systems ship in fixed configurations with limited options. At the same time, well-engineered mechanical systems can be highly configurable, using modular components to accommodate a wide range of layouts, angles, and design requirements. When comparing systems, look closely at what a specific manufacturer actually offers — don't assume one connection method automatically means more (or fewer) choices. ### Building Code Requirements Every metal staircase must comply with the building code that applies to its use and occupancy type. In the United States, three codes are most relevant: * **IRC (International Residential Code):** Applies to private residential dwellings. The IRC establishes minimum requirements for stair width, headroom, and riser and tread dimensions to ensure safety. This is the code most homeowners will work under. * **IBC (International Building Code):** The IBC applies to all stairways except those under industrial or residential occupancy classifications, meaning it covers general-use commercial buildings. It is updated every three years by the International Code Council. * **OSHA:** OSHA regulates stairways in working environments or areas inaccessible to the public, such as factories and warehouses. IBC standards are generally more stringent than OSHA requirements, which means compliance tends to cost more, but it also provides a higher level of safety and may be required if your space ever becomes accessible to the public. Your local building department will tell you which code applies to your project. When in doubt, it's worth confirming before you finalize your design, especially for mixed-use or commercial spaces. For a state-by-state reference, see this [building codes by state resource](https://www.buildingsguide.com/blog/resources-building-codes-state/). ### How Viewrail's Mechanical Stair Systemss Work Every FLIGHT system is built around the same core mechanical engineering, regardless of which system you choose. **The Stringer** The stringer is the steel backbone. Depending on the system, it's either exposed as a design element (Mono, Mono Select), hidden inside the wall (Cantilever), or concealed within the staircase structure itself (Stack). **Header and Footer Plates** The header plate connects the top of the stringer to the upper floor framing. The footer plate anchors the bottom to the floor. Each plate is secured with six bolts, engineered to exceed five times the recommended load requirement. **Tread Brackets** Tread brackets attach to the stringer and support each tread. In Mono, they're visible. In Mono Select, they're hidden. In Cantilever and Stack, the structural approach is different — but the principle of precision bolted connections throughout is the same. **Hardware** Every connection uses Grade 8 bolts — among the highest-strength fasteners for standard structural applications. Each bolt receives a thread-locking adhesive during production to prevent loosening, resist corrosion, and keep connections tight over time. **Flow Drilling** Rather than welding components together, Viewrail uses flow drilling to create clean threaded connection points in the steel tubing. This eliminates the heat distortion and visible scarring that welding can leave on finished metalwork, and allows the stringer and brackets to ship separately — making delivery and installation significantly more manageable.

A Viewrail FLIGHT Mono system with Vedera glass railing.

### Which System Is Right for You? Both welded and mechanical prefab stairs are proven, code-compliant options. Here's a quick way to think through the decision: * **Choose a welded system** if you want a fully prefabricated unit with minimal on-site assembly and you have easy site access for a larger delivery. * **Choose a mechanical system** if you're working in a finished home, need components to ship separately, or want to avoid any on-site welding. Whichever direction you go, evaluate the specific manufacturer's configuration options — and confirm with your local building department which code governs your project before finalizing your design. ### Related topics * [Types of Staircases](/guides/about-stairs-and-railing/types-of-staircases.md) — Compare this system type with other common stair layouts. * [What are Floating Stairs](/guides/about-stairs-and-railing/what-are-floating-stairs.md) — Understand how mono stringer and other floating stair systems are supported. * [How Can I Customize My FLIGHT Staircase?](/guides/planning/how-can-i-customize-my-flight-staircase.md) — Explore finish, railing, and configuration options for a mechanical stair system. * [How Do I Install a FLIGHT System?](/guides/install/how-do-i-install-a-flight-system/how-do-i-install-a-flight-mono-system.md) — Review blocking, subfloor, and install planning before assembly. * [How much do FLIGHT Floating Stairs Cost?](/guides/pricing/how-much-do-flight-floating-stairs-cost.md) — Estimate how system type and configuration affect budget. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://resources.viewrail.com/guides/about-stairs-and-railing/types-of-staircases/prefab-metal-stairs-welded-vs.-mechanical-systems.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.