Structural steel detailing services, delivered fabrication-ready.

What a steel detailing package contains

Steel detailing is the last translation between an engineer's design and a shop that has to cut metal. It has to be complete, internally consistent and readable by people who will never get the chance to ask a question about it.

A full package carries:

• Erection drawings — plans, elevations and sections with assembly marks, grid references, working points, levels and field bolt requirements.
• Assembly and single-part drawings — every fabricated piece dimensioned, with holes, copes, bevels, cambers, and surface treatment notes.
• Connection details detailed to the engineer of record's design, with bolt grades, hole types, weld sizes and edge preparation called out.
• Anchor bolt and embed plans, issued early so foundations are never waiting on steel.
• Advance and final bills of material, bolt and washer lists, weld summaries and assembly weights.
• Fabrication data — NC1/DSTV for the beam and plate lines, DXF for nesting, and exports for your fabrication management system.
• The model, delivered as a native file and as IFC, so the package and the model never diverge.

Marks, prefixes and sheet numbering follow your fabricator's conventions, not ours. A package that forces a shop to renumber has already cost you a week.

Miscellaneous metals and secondary steel

Main frame steel is the part everyone programmes. The part that slips is everything bolted to it: stairs and landings, handrails and guarding, ladders and their safety cages, access platforms and walkways, grating and chequer plate, pit and trench covers, gates, bollards, plant and equipment support steel, and the framing that carries somebody else's façade.

Miscellaneous metals slip for a structural reason, not a lazy one. They interface with every other package, their geometry is the last to be fixed, and a good number of them cannot be dimensioned until something already built has been measured. So they are run as a package with explicit hold points: which items are field-measured and when, which depend on a supplier drawing that has not arrived, and which can be released now without regret.

Geometry is checked against the access and guarding rules that apply rather than drawn to look right — rise, going, headroom, guard height and infill spacing to IBC Chapter 10 with OSHA 1910.25 and 1910.28 in the United States, EN ISO 14122 for permanent means of access to plant, and BS 5395 for stairs with BS 4592 for open-bar flooring in the United Kingdom. Grating span, load class and fixing type are called out, not left to whatever the supplier's catalogue defaults to.

The same package discipline covers the framing that is repetitive rather than difficult — roof trusses, joists and metal deck, vertical and horizontal bracing, and pre-engineered building frames. The risk there is not complexity. It is that one wrong dimension is faithfully reproduced ninety times.

How the work runs, end to end

Work starts with an intake review rather than with modelling. We read the structural drawings, the specification, the connection design basis and the existing RFI log, and we come back with the list of things that will stop the package later: missing grades, undefined connections, conflicting levels, details drawn at two different scales that do not agree.

Then the model is built. The AI-driven part of the work is the repetitive part — framing, member preparation, connection instances against approved standard details, drawing creation, dimensioning, marking and the bill of material. Senior detailers and engineers spend their time where judgement actually lives: non-standard connections, erectability, sequence, and the questions worth raising with the design team.

Issue is controlled. Every drawing goes out under a revision, against a register, with a change list your reviewer can read in a minute. Approval comments come back into the same register, are actioned, and are shown as actioned. When a package is released for fabrication, the release is a decision someone signed, not a folder that happened to be up to date.

Machine-checked before a person reviews it

Automated quality control runs on the model and the drawing set together, before a reviewer opens anything. It is not a spell-check. The checks are the ones a good checker runs and gets tired of running:

• every mark used on a drawing exists in the model, is unique, and appears in the bill of material;
• member sizes, lengths, cambers and grades on the sheet match the model they were cut from;
• bolt edge distances, gauge lines and hole clearances against the governing specification;
• weld symbols complete and legal, with size, type and side defined;
• dimension chains that close, and dimensions that are not text overrides;
• clashes between steel, embeds, and the architectural and services models where those are available;
• the sheet register matches the issued set, and the revision on the sheet matches the revision in the register.

The reviewer sees what was checked and what failed, not just a clean drawing. That is the difference between quality control and hope. A senior engineer then reviews the package and signs it, and that signature is the thing you are actually buying.

Detailing to the code your project is built under

The same frame is detailed differently in Chicago, Manchester, Frankfurt and Brisbane, and the differences are not cosmetic. Hole sizes, tolerances, mark conventions, what the fabricator is allowed to assume, and who owns the connection design all move with the code.

• United States — AISC 360 with the AISC Code of Standard Practice (AISC 303) governing detailing responsibility and tolerances, and AISC 341 where seismic provisions apply.
• Eurocode — EN 1993 with the relevant National Annex, executed to EN 1090-2 with the execution class agreed and reflected in the drawings.
• United Kingdom — BS EN 1993 with the UK National Annex, and the drawing conventions British fabricators expect.
• Canada — CSA S16 for design, the CISC Code of Standard Practice for detailing responsibility and tolerances, and CSA W59 for welded construction.
• Australia and New Zealand — AS 4100 for design and AS/NZS 5131 for fabrication and erection, including the construction category.
• Drawing conventions — welding symbols to AWS A2.4 or ISO 2553 depending on the region, and title blocks and sheet layout to ISO 7200 or your own manual.

Material and fastener specifications move with the code as well, and they belong on the drawing rather than in somebody's head: ASTM A992, A572 and A36 with A500 or A1085 hollow sections and F3125 high-strength assemblies in North America; EN 10025 grades from S235 to S460 with EN 10210 and EN 10219 hollow sections, preloaded assemblies to EN 14399 and non-preloaded to EN 15048 in Europe. Welding is called up to AWS D1.1 or to EN 1090-2 with EN ISO 3834, and the sheet says which, because the procedure qualification behind the symbol is not interchangeable between them.

Some code requirements land on a detail rather than on a calculation, and those are the ones a checker forgets. A column base on a United States project carries four anchor rods and is detailed for the erection stability rules of OSHA 1926 Subpart R; a two-rod base is a drawing the erector is not permitted to build to, however well it works structurally. Rules of that kind live in the automated checks rather than in anyone's memory.

Because the checks are configured per code rather than per detailer, a programme that spans two standards does not quietly get detailed to one of them.

Data the shop can run on

A drawing that a shop has to re-key is only half a deliverable. The model is built so the fabrication data falls out of it correctly the first time: NC1/DSTV files for saws, drill lines and plate processing, DXF for plate nesting, and structured exports for fabrication management and purchasing.

The practical detail matters here. Assembly weights and painted areas are computed from the model rather than estimated. Transport lengths and lifting weights are visible on the erection set. Galvanising is planned for, with vent and drain holes shown rather than left for the galvaniser to invent. Part marks on the drawing are the part marks on the traveller.

If your fabricator works in Tekla Structures, SDS/2 or Advance Steel, we deliver in it. If several parties need the same geometry, IFC is issued alongside the native file, and the two are checked against each other before issue.

Take-off and tonnage, before the package exists

Long before anything is released for fabrication, somebody has to put a number on the steel. That number is usually produced twice — once to price the work and once, properly, to build it — and the two rarely agree. We cut both from the same model.

An estimating model is built to the level of detail the number needs and no further: enough framing, enough grades and enough connection typicals to make the tonnage honest, without detailing a job at risk. From it come:

• tonnage by member class, section, grade and finish, split the way your estimator prices;
• a connection material allowance derived from the typical details rather than applied as a flat percentage;
• bolt counts by grade, diameter and length, and weld length with a consumable estimate;
• plate quantities with nesting yield and a realistic offcut allowance;
• painted and galvanised surface areas computed from geometry;
• piece counts, assembly weights and transport loads for erection and logistics planning.

When the design moves, the take-off is re-cut rather than re-estimated, and the delta between two revisions is visible instead of argued about. The same model then carries on into the detailing package, so the tonnage you priced and the tonnage you fabricate have a traceable relationship.

Where the steel work lands

Steel detailing is not one job. A stadium roof, a data centre plant deck, a highway bridge and a warehouse portal frame ask for different things from the same package.

• Industrial and manufacturing buildings — high repetition, tight programme, heavy craneage and equipment support steel.
• Stadiums and long-span roofs — geometry that has to be solved before it can be drawn, and erection sequences that drive the detailing.
• Bridges — plate girders, splices, camber diagrams and fabrication tolerances that leave no room for interpretation.
• Data centres — repetitive modules where a single detail error is repeated a hundred times, which is exactly where automated checking pays.
• Airports, metro and transport structures — heavy coordination load with services, cladding and civils.

Sector experience is not a slogan on this site; it changes which checks are switched on and which questions get asked at intake.

One partner, one signature

BuildTwin takes the scope, produces the package, checks it and signs it. There is one delivery lead, one register, one programme, and one company answerable for what is on the drawing — not a pool of people you have to manage.

That has practical consequences. Confidentiality is contracted once, not per person. Your model, your standard details and your fabricator's conventions stay inside the engagement. We work inside your common data environment where you have one, and where you do not, we run the exchange and hand you the register at the end.

Capacity does not change the arrangement. When the programme needs more drawings per week, the system produces more drawings per week; the review and the signature stay with the same senior engineers.