The planning takeaway
Compare complete structural systems, not isolated steel sizes or a single connection. Every member and connection needs to fit the same project-specific design.
Choosing how the frame is connected? Compare weld-up vs. bolt-up steel buildings.
Engineered rigid frames are the backbone of our red iron buildings and many commercial projects.
Review the trim, fasteners, and hardware in our building components reference.
Planning to heat or cool the building? Compare metal building insulation options early in the design.
01
Columns and primary supports
Columns or posts are vertical supports that transfer loads toward the foundation. Steel tube or pipe posts may be part of a weld-up system; engineered steel columns are common in red iron frames; wood columns are typical in wood post-frame buildings.
Support size and anchorage cannot be selected from appearance alone. Foundation connections must address the loads and conditions of the actual building.
02
Trusses and rigid frames are not the same
A truss uses connected members to span between supports. The J & I manual shows steel trusses supported on steel posts. Wood post-frame packages often use engineered wood trusses.
A red iron building commonly uses rigid steel frames with columns and rafters connected through engineered joints. Not every steel roof support is a truss, and not every metal building uses the welded details in the manual.
03
Purlins, girts, and roof supports
Roof purlins span between primary roof supports and support the roof assembly. Wall girts support wall cladding. Cold-formed steel C or Z members are common secondary framing in steel systems; wood members serve comparable roles in many wood post-frame buildings.
Spacing, orientation, laps, attachments, and any bridging depend on the selected system and design. Interior liners, insulation, and planned fixtures should also be coordinated with the framing rather than added without review.
04
Bracing and the load path
A building must resist more than the weight of its roof. Wind creates lateral forces and uplift. Bracing, connections, and the specified roof and wall assemblies help deliver these forces through the structure to the foundation.
The manual describes a longitudinal member along truss bottom chords, called a “rat run,” to tie trusses together. That example is not a substitute for a complete bracing design. Temporary erection stability and permanent bracing both require the correct plans and procedures.
05
Three common systems, three different details
Wood post-frame: wood columns with trusses and secondary wood framing, using the support and connection details specified for that package. Metal siding may enclose the wood structure.
Weld-up steel: steel supports and roof framing joined with project-specific welded details, often with steel purlins and girts. Welding, erection, and foundation connections require qualified work and the appropriate design.
Bolt-up / red iron: an engineered steel building package, commonly with rigid primary frames, bolted connections, and cold-formed secondary framing. Follow that package’s drawings and assembly requirements—not a weld-up manual.
06
Choose around use, openings, and future plans
Tell the builder the clear working space, equipment height, door layout, insulation plans, and any future additions you want. These decisions can affect the primary frame, bracing locations, foundation, and complete building envelope.
Use our existing frame diagrams to visualize the systems and the comparison page to discuss trade-offs. Neither diagrams nor this guide replace engineered structural information.
Questions to ask your builder
- Is this a wood post-frame, weld-up, or engineered bolt-up package?
- Who supplies the project-specific structural and foundation plans?
- Where will bracing be located relative to my doors and workspace?
- Can the frame accommodate the future changes I have in mind?
Technical reference & important limits
J & I Manufacturing Building Instructions, PDF pages 3–5: steel posts, truss connections, roof and wall C-purlins, and longitudinal truss restraint. Its welded steel examples do not govern wood or red iron systems.
This guide is for planning and education, not installation instructions or engineered drawings. Structural design, foundations, connections, spacing, loads, and code compliance require project-specific plans and qualified professional guidance.
