KXD Steel Technical & Project Team | Design, Detailing & Project Delivery | Published: August 27, 2026
Structural steel building construction runs in ten stages: load definition, structural design, detailing approval, material procurement, CNC cutting, welding, surface treatment, trial assembly, export packing, and site erection. Each stage produces a document or a physical check that must pass before the next begins.
Process descriptions and product parameters below reflect KXD capability and product-page data current as of August 2026. Sequence and inspection points are customizable to contract and destination-country requirements.
The reason to walk this sequence rather than treat fabrication as a black box is practical. For a plant manager, every one of these stages contains a decision point where a change is cheap, and a point shortly after where the same change becomes expensive. Knowing which is which is most of what separates a project that lands on schedule from one that does not.
Stage 1: Build the load schedule before anything else
A structural engineer cannot start until the loads are known, and loads on an industrial building come from your process, not from a catalogue.
What to assemble:
- Overhead crane capacity, span, number of cranes per bay, and duty class
- Machinery footprints and any equipment loads suspended from the roof structure
- Mezzanine floors, their live load, and whether they are structurally independent
- Roof-mounted plant: HVAC, dust extraction, solar
- Process-specific constraints such as hot work zones, washdown, or corrosive atmosphere
- Local design values for wind, snow and seismic, obtained from the destination-country authority
Checkable output: a single load schedule document, signed off by whoever owns the production layout. If the production manager has not seen it, it is not finished.
The single most common failure in this stage is treating future equipment as out of scope. A crane installed in year four still changes the columns designed in year zero.
Stage 2: Structural design against the correct code
Design begins once the load schedule and the site geometry are fixed. Two decisions govern the outcome.
Code selection. Design standards available across KXD’s product range include GB, ASTM, AISI, JIS, BS, DIN and EN. The governing code is whichever your local building authority will accept for permit. State it in the contract, because a frame designed to one code cannot be retroactively certified against another without recalculation.
Material grade. Q235B and Q355B welded H-sections are both standard. Q355B carries higher yield strength, which allows lighter sections and lower shipping weight; Q235B costs less per ton. On crane-loaded or long-span industrial frames, the tonnage reduction usually favours Q355B.
Design work at this stage runs through Tekla, PKPM and 3D3S, which produce the analysis model that later generates fabrication data directly.
Checkable output: a structural calculation report naming the design code and the wind, snow and seismic values used. Read the input values. If they do not match the numbers your local engineer supplied, stop and resolve it now.
Stage 3: Detailing and the drawing approval gate
Detailing converts the analysis model into shop drawings: every member, every connection, every bolt hole, every weld.
This is the hardest gate to appreciate from the buyer’s side, because approving drawings feels like paperwork. It is not. Once drawings are released to the shop, steel is cut against them. Changes after this point mean re-cutting, and re-cut steel is scrap.
What to actually check on the approval drawings:
- Clear span and eave height measured internally, matching your layout
- Door and opening positions against your traffic flow and dock arrangement
- Crane runway elevation, and hook height clearance to stored or in-process material
- Column positions against machinery footprints, particularly at the perimeter
- Anchor bolt layout, which the civil contractor needs before the foundation is poured
Checkable output: a stamped or written approval of the shop drawing set, with a revision number. Keep the revision number. Every later dispute references it.
Stage 4: Material procurement and mill certification
Steel is ordered against the approved drawings. Each heat of steel arrives with a mill test certificate stating chemical composition and mechanical properties.
Checkable output: mill certificates covering the grades in your building, traceable to the material used. Ask for them at this stage rather than at delivery. A supplier who can produce them promptly is running material traceability; one who cannot is reconstructing paperwork later.
Stage 5: CNC cutting and drilling
Fabrication data flows from the detailing model to CNC equipment, which cuts plate and profile and drills bolt holes to the drawing dimensions. Cutting from model-generated data rather than manually transcribed dimensions removes a category of error that used to dominate fit-up problems on site.
Checkable output: dimensional inspection records on cut components, sampled against the drawing. On a large order, ask for the sampling rate rather than a blanket statement that inspection occurred.
Stage 6: Assembly and welding
Cut plates become welded H-sections and connection assemblies. Automated welding handles the long, repetitive web-to-flange welds; manual welding covers connections and geometry the automated line cannot reach.
Welding is the stage where quality is decided and where it is hardest to see afterwards. Two things make it verifiable:
WPQR. Welding Procedure Qualification Records document that a specific procedure, on a specific material grade and thickness range, has been qualified by test. KXD lists WPQR as available on request. Request the records covering the joint types and thicknesses in your building, not a general statement of welding capability.
Non-destructive testing. Ultrasonic or radiographic testing on full-penetration welds, at a rate specified in the contract. Third-party inspection through SGS, Bureau Veritas or Intertek can be arranged on request. Note that specific inspection reports are generated per project, so any report shown to you should reference your order, not a previous one.
Checkable output: WPQR covering your weld types, plus NDT reports referencing your project.
Stage 7: Shot blasting and surface treatment
Welded components pass through shot blasting to remove mill scale and rust before coating. Coating adhesion depends almost entirely on what happens here, which is why the surface preparation grade belongs in the contract alongside the paint specification.
Two coating routes are used on industrial buildings:
Paint systems. Primer plus intermediate and topcoat, with total dry film thickness specified in microns. Suited to normal industrial atmospheres, and repairable in the field.
Hot-dip galvanizing. Zinc coating applied by immersion. Longer service in corrosive environments and lower maintenance, at higher cost. It carries a physical constraint worth knowing early: components must fit the galvanizing bath, which limits member length and sometimes forces a splice that a painted member would not need.
For a coastal site, a high-humidity process, or anything involving chemical exposure, the coating decision has a larger effect on twenty-year cost than the frame design does.
Checkable output: dry film thickness readings, or galvanizing coating weight records, against the specified values.
Stage 8: Trial assembly and finished-product inspection
Complex sections are trial-assembled in the shop before shipping. The purpose is to find fit-up problems where they cost hours instead of finding them on site where they cost weeks.
Checkable output: finished-product inspection records, and where trial assembly applies, photographs or a report confirming fit. For a first order with a new supplier, a pre-shipment inspection by a third party is worth its cost.
Stage 9: Marking, packing and export documentation
Every component is marked with a piece mark that corresponds to the erection drawings. This is the link between a container full of steel and a building.
Packing sequence matters more than it appears. Components should be loaded so that what is erected first is unloaded first, and bolts, connection plates and small parts should be packed in labelled boxes that arrive with the frames they belong to, not in a separate later container.
Container geometry is a real constraint on member length. Standard 40 ft containers accommodate members around 12 m; longer members require flat rack or open top, which changes freight cost and sometimes the splice design. If your detailing produces 15 m members, the freight implication should be discussed at detailing stage, not at booking.
Checkable output: a packing list matched to piece marks, plus the export document set — commercial invoice, packing list, bill of lading, certificate of origin, and any destination-specific documentation.
Confirm the incoterm at contract stage. FOB, CIF and DAP produce different numbers for the same building, and they place the freight, insurance and customs clearance responsibilities in different hands.
Stage 10: Foundation acceptance and on-site erection
Foundations are designed against local soil conditions and built by a local contractor. The interface between their work and the imported steel is the anchor bolt layout, and that interface is where site delays concentrate.
The erection sequence:
- Survey the anchor bolts against the approved layout before any steel arrives on site. Position tolerance errors found now are correctable; found after the first frame is lifted, they are not.
- Erect the first braced bay and confirm it is plumb and square. Every subsequent frame references this one, so an error here propagates through the building.
- Install remaining frames with temporary bracing maintained until permanent bracing is complete. Temporary bracing removed early is a common cause of erection incidents.
- Fit purlins and permanent bracing, then re-check plumb before high-strength bolts are finally tightened.
- Install roof cladding first, then walls. A watertight roof lets interior work start while walls continue.
- Fit openings and accessories: doors, roller shutters, skylights, ventilation, gutters and downpipes.
- Punch-list walk-through with the erection supervisor, recording every item before demobilization.
Checkable output: an as-built survey confirming plumb and alignment tolerances, plus a signed punch list.
KXD supplies installation support rather than a full local labour force on most export projects, so the erection contractor is typically local. Confirm who supervises, who provides lifting equipment, and who is responsible for correcting fit-up problems, in writing, before steel ships.
The Custom Steel Structure Building specification this process produces
The stages above apply to the general-purpose product before it is configured as a workshop, magazzino or plant building:
- Main frame: Q235B or Q355B welded H-section
- Clear span: up to 100 m single-span
- Building height: 3–30 m
- Roof slope: 1:10 to 1:5
- Wind resistance: up to 160 km/h, customizable to local code
- Cladding: single-skin steel, EPS, PU, rock wool or glass wool
- Design lifespan: 50+ years
- Minimum order: 600 m²
- Published supply capacity: 8,000 tons/month
- Published price range: USD 40–100/m², depending on specifications
Read the capacity figure correctly. 8,000 tons/month is a shop capacity statement, not a promise about your delivery date. Lead time depends on tonnage, connection complexity, coating route and current shop loading. Get the schedule in writing at order stage.
The MOQ of 600 m² exists because the fixed costs in Stages 2, 3 and 9 do not scale down. Engineering hours, detailing and export documentation cost roughly the same for a 400 m² building as for a 4,000 m² one.
Where the certificates fit in the sequence
Certification is easier to interpret once mapped onto the stages above.
The European Commission states that CE marking for construction products indicates conformity with declared performance assessed under a harmonised European standard or European Technical Assessment, with Commission material specifically referencing EN 1090 for structural products. EN 1090 covers the execution of steel structures and the factory production control behind it, which means it applies to Stages 5 through 8. For a European destination, this is the certificate that gets checked at permit stage.
ISO identifies ISO 9001 as its quality-management-system standard, ISO 14001 as its environmental-management-system standard, and ISO 45001 as its occupational health and safety management-system standard. These certify how the factory is managed, not the structural performance of your building.
For North American projects, the American Institute of Steel Construction (AISC) is the reference body for fabricator certification, including complex coating endorsements relevant to Stage 7.
Compared with buying a fixed-model kit building through a retail metal-building channel, this ten-stage route takes longer to reach a firm price and requires more input from you at Stages 1 and 3. What it returns is a frame sized against your actual loads and a document trail at every stage. Catalogue models are sized for a range of conditions, which usually means paying for capacity the building will never use, and they rarely accommodate a 30 t crane or a 60 m clear span at all.
Two stages where problems actually originate
Stage 3, not Stage 10. Site fit-up problems are visible during erection, so that is where they get blamed. Most of them were created at detailing approval, when a dimension nobody checked went to the shop. The cost of an hour spent on drawing review is not comparable to the cost of a re-cut member arriving six weeks later.
Stage 10’s foundation interface. Anchor bolt setting-out is done by a local contractor working from a drawing produced 8,000 km away. Position and elevation tolerances are tight, and cast-in bolts cannot be moved once concrete cures. Survey them before steel arrives. Where errors are found, correction options exist — enlarged base plates, drilled anchors, grouting adjustments — but all of them require engineering approval, and all of them take less time when discovered before the crane is booked.
FAQ
Q: How long does the whole process take from order to erected building?
A: It varies with tonnage, connection complexity and coating route, and the shipping leg depends on destination. No responsible figure can be given without those inputs. Ask for a stage-by-stage schedule at order confirmation, showing detailing approval, fabrication, shipping and erection windows separately.
Q: At which stage can I still change the design without cost?
A: Freely up to Stage 2, at recalculation cost during Stage 3, and at material cost after drawings are released to the shop in Stage 5. Changes after cutting mean scrap.
Q: Who is responsible for the foundation?
A: The buyer, through a local contractor. The fabricator supplies anchor bolt layouts and reactions; local soil conditions determine the foundation design, which is why it is procured locally.
Q: Can I have third-party inspection during fabrication?
A: Yes. SGS, Bureau Veritas and Intertek are available as third-party testing options on request. Specify the inspection points and the hold points in the contract, because an inspection nobody scheduled will not happen.
Q: What documents should arrive with the shipment?
A: Packing list matched to piece marks, erection drawings, mill certificates, welding and NDT records, coating thickness records, and the export document set. Request the technical file as a deliverable in the contract, not as a favour at shipping.
Q: Does galvanizing change the design?
A: It can. Members must fit the galvanizing bath, which places a limit on component length and can require a splice that a painted member would not need. Raise the coating decision at Stage 2, before detailing fixes member lengths.
About the author
The KXD Steel Technical & Project Team includes more than 100 senior engineers and technical professionals, along with over 50 designers, architects, detailers and consultants. The team handles design, detailing, fabrication and delivery of prefabricated steel structures for industrial, commercial, logistics, agricultural and infrastructure applications, with project and market experience across more than 80 countries and regions. In-house engineering runs on Tekla, PKPM and 3D3S; manufacturing covers CNC cutting, automated welding, shot blasting, surface treatment, component assembly and finished-product inspection.
27 agosto 2026 
