Steel Systems Guide
The Core Distinction
In North American construction, steel joists and girders are the backbone of many structures. Understanding their distinct roles is the first step to mastering steel system design.
Joist: The Secondary Support
A steel joist is a secondary framing member. Its primary job is to support the weight of floor and roof systems and transfer those loads to the main frame. Think of them as the "ribs" of the structure, providing direct support for the surfaces we walk on and that shelter us.
Girder: The Primary Support
A joist girder is a primary load-carrying member. It's a main horizontal support that connects columns and carries the combined weight from all the smaller joists. Girders are the "spine" of the structure, collecting all the distributed loads and channeling them to the foundational columns.
Structural Hierarchy
Column
Column
JOISTS (Secondary)
This diagram shows how joists rest on and transfer their loads to the main girder, which in turn is supported by the columns.
Explore Steel Joist Types
The Steel Joist Institute (SJI) standardizes joists into series based on load and span. Select a series below to see its specifications and typical applications.
The Detailing & Fabrication Process
Steel detailing translates engineering plans into precise instructions for manufacturing and assembly.
Initiation
Analysis
3D Modeling
Detailing
Finalization
Estimation & Market Factors
A successful bid requires a precise estimation that accounts for all costs, from raw materials to on-site labor, while navigating a volatile market.
Components of a Steel Estimate
The total cost is more than just the price of steel. A comprehensive estimate includes fabrication, erection, and various auxiliary costs. Hover over the chart to see how these components contribute to the total project budget.
- Material Costs
- Fabrication Costs
- Erection/Installation Costs
- Auxiliary & Soft Costs