Tendering and estimating, 29 October 2026
AI tendering for steel and metal fabricators
Price a metalwork tender from a cut list and steel weight, then add fabrication hours, galvanising, powder coating, site measure, installation and connection design as separate lines. Keep the steel price valid for a short, stated period. Before pricing, find out who designs the connections and fixings into the structure, and check every barrier against Approved Document K heights.
What makes metalwork tenders hard to price?
The drawing shows the shape; the money is in the details nobody drew. A balustrade package might give elevations and a spec clause saying "contractor to design", with no connection details and no site dimensions.
The problems that come up on most gate, railing, stair and balustrade packages:
- Pricing from drawings. Architect's drawings rarely show every section size, plate and weld, so you build the cut list yourself.
- Steel price changes. Your merchant price may not hold until the order.
- Galvanising and powder coating. Lead times, transport between works, and colour or system specs.
- Site measure. Fabricating to drawing sizes on existing buildings leads to remakes.
- Connection design. Who designs the fixings into the structure, and whether the substrate can take them.
- Building regulations for barriers. Guarding heights, gaps and loads under Approved Document K.
- Product conformity. Fabricated structural steelwork must carry UKCA or CE marking.
One metal fabrication firm we spoke to, eight staff plus four subbies, had recently lost its office manager and described the admin as "a bit carnage". Supplier invoices were being split across jobs by hand, which is where a metalwork firm finds out too late that the galvaniser's bill wasn't in the price.
How do you price a stair and balustrade package?
Work out the steel weight from the cut list, then price each stage of the work. Your margin goes on top of the total cost.
External escape stair and 46 m of balcony balustrade for a block of flats
2.6 t of steel in total from the cut list, galvanised and powder-coated. Rates are illustrative; use your own merchant, galvaniser and labour costs.
| Steel: sections, plate and flats2.6 t × £1,150 | £2,990 |
| Fabrication168 hours × £42 | £7,056 |
| Hot-dip galvanising2.6 t × £650 | £1,690 |
| Powder coatingquoted lump sum | £2,100 |
| Site measure before fabrication2 people × 1 day × £280 | £560 |
| Installation2 fitters × 6 days × £280 | £3,360 |
| Resin anchors and fixings | £480 |
| Connection design by a structural engineer | £1,200 |
| Delivery and HIAB | £950 |
| Total cost | £20,386 |
| Tender price at 15% margin£20,386 ÷ 0.85 | £23,984 |
Steel isn't the biggest cost here: fabrication hours are. But steel is the line most likely to move between tender and order, and a long validity period gives the main contractor a free option on your margin. Quote the date of your merchant price and hold it for 30 days, or price steel as a stated rate per tonne adjusted at order.
Who designs the connections?
Whoever the drawings and scope say, and if they don't say, assume the main contractor will argue it's you. Connections and fixings into the structure carry the load, so this is a design question with real liability.
Fabricate and install to the details. Qualify that changes to connections are revalued and that you're not responsible for the design.
Ask who designs the fixings into the structure. If it's you, price an anchor supplier's or engineer's design and pull-out tests.
Price a structural engineer's design and calcs, check your insurance covers design, and allow time for approval before fabrication.
Send a clarification asking who designs connections and fixings. If there's no answer, qualify that design is excluded.
What do the rules say about barriers and steelwork?
Barriers must meet Approved Document K heights and loads, and fabricated structural steelwork must be UKCA or CE marked to BS EN 1090-1.
On structural steelwork, Steel Construction Info says all fabricated structural steelwork delivered to a site in Great Britain must be UKCA or CE marked against BS EN 1090-1. That needs a factory production control certificate and a welding certificate from a UK Approved Body, and a Declaration of Performance. The engineer sets the execution class, and EXC2 is usual for most UK buildings. If a tender asks for EXC2 and you aren't certified, you can't supply that steelwork. Whether a particular stair or balustrade counts as structural steelwork is a question for the engineer, so ask before you price.
These rules are for England and Great Britain. In Northern Ireland, construction products must comply with the EU rules and carry CE marking, with UKNI only alongside CE. Wales and Scotland have their own building regulations for barriers, so check the local guidance for jobs there.
What should a metalwork tender qualify?
Steel price validity, finishes, site measure and fixings into the structure. Those four cover most of the arguments on metalwork packages.
Tender: project, architectural metalwork package Our price: £amount excluding VAT, dated date Steel price 1. Steel priced at our merchant's quotation of date. Price valid for 30 days; after that, steel adjusted at the merchant's price on the order date, with invoices shown. Finishes 2. Finish: hot-dip galvanised to standard and powder-coated RAL colour, system. Colour samples and finish changes after order are a variation. 3. Galvanising and powder coating lead time number weeks, included in our programme from order. Site measure and programme 4. Fabrication to our site measure, taken when structure, balcony slabs, stair cores are complete. Remakes caused by later changes to the structure are a variation. 5. Programme: number weeks from signed-off drawings and order to installation. Design and fixings 6. Connection design: by others / by our engineer, included. Fixings into structure as detail, assuming concrete grade, substrate. Pull-out tests included / excluded. 7. Barriers to Approved Document K heights shown on drawings. Site 8. Crane or HIAB access to within x m of each installation point. Hoisting, scaffolding and edge protection by others unless listed. 9. Making good to finishes around fixings, and touch-up of site damage by others, excluded.
For the general lines on payment and attendances, use the tender qualifications and exclusions template. The same firm asked whether the VAT reverse charge was applied automatically on its invoices; if you work for VAT-registered contractors under CIS, read does the domestic reverse charge apply before your first application.
What can AI do on a metalwork tender, and what can't it?
AI is strong on the cut list and the reading. It can't tell you whether a slab edge will take an anchor.
What AI does well:
- Builds the cut list and weight from elevations and sections, with section sizes from the spec. See can AI do a take-off from drawings for where measuring from drawings works.
- Checks barriers against Part K: heights, gaps and whether the building type triggers the 100 mm sphere rule.
- Finds design responsibility and execution class wording in the spec and contract.
- Drafts qualifications with today's steel price date and the drawing references filled in.
The Tenders assistant reads a balcony and stair package and flags open connection design.
What still needs the fabricator:
- The site measure. Real dimensions, levels and out-of-square structure.
- Buildability. How a stair goes in, where you can weld on site, how the finish survives installation.
- Fabrication hours. Only you know how long your shop takes on this detail.
- Risk and sign-off. Design liability and the price.
How do you win more metalwork tenders?
Make your price easy to compare and your risk clear. A fabricator who shows the cut list, the finish system and the programme is easier to appoint, because those are the things that go wrong.
- Show steel weight and finish on the price, so the estimator sees what's included.
- State design responsibility first.
- Hold steel prices for a short, stated period.
- Use the 10-minute tender read to drop packs with open-ended design or no site measure.
Where Nexley fits
Nexley is the AI back office for UK trade firms: five AI assistants run your tenders, quotes, buying, scheduling and invoicing. It connects to the tools you already work in, you run it all from WhatsApp, and you approve everything. £799 a month.
For metalwork tenders, Nexley reads the pack you forward on WhatsApp, builds a cut list and steel weight from the drawings, checks barriers against Approved Document K, prices from your merchant, galvaniser and labour rates, and drafts qualifications for steel validity, finishes and connections. You check the site measure and the fabrication hours and approve the price.
Common questions
How do you price a steel balustrade?
From the cut list: steel weight at your merchant price, fabrication hours, galvanising by weight, powder coating, site measure, installation, fixings and any design. Add your margin to the total cost. A rate per metre only works once you know your costs on a similar detail.
How long should a steel price be valid?
Short, and stated. Thirty days from your merchant's quote, with steel adjusted at order after that, keeps the risk manageable. A 90-day validity on a volatile material puts the risk on you.
What height does a balcony balustrade need?
Under Approved Document K in England, external balconies on a dwelling need guarding at 1,100 mm. In other buildings, 900 mm on stair flights and 1,100 mm elsewhere is typical. Check the building type in Diagram 3.1.
Do I need BS EN 1090 certification?
To supply fabricated structural steelwork to a site in Great Britain, yes: it must be UKCA or CE marked to BS EN 1090-1. Ask the engineer whether the items in your package count as structural steelwork.
Sources
- GOV.UK: Approved Document K, protection from falling, collision and impact
- Steel Construction Info: UKCA marking and the Construction Products Regulations
Every rule, rate and date above was checked against these sources on the date shown at the top.
Topic: Tendering and estimating
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