How to Quote and Run a Commercial Steelwork Installation

What you will learn

• How to assess scope, Execution Class, and site-specific constraints before pricing a steelwork tender.
• How to build a line-by-line estimate covering sections, fabrication, coatings, transport, and erection costs.
• What to include in your tender submission so the main contractor can evaluate your price and programme with confidence.
• How to manage the fabrication and delivery sequence from contract award to first erection day on site.
• What your RAMS must cover and how to protect your programme when other trades affect your erection sequence.
• The UKCA documentation, as-erected records, and retention close-out steps required at handover.

A commercial steelwork package is one of the most technically demanding sub-contracts on any construction project. You are responsible for producing a competitive tender from drawings that may still be evolving, fabricating steel sections to precise tolerances in a workshop miles from site, and delivering and erecting them to a programme that multiple other trades depend on. Get the estimate wrong and you build the frame at a loss. Get the programme wrong and the main contractor looks to you first when delays need explaining. This guide walks through the full process, from tender assessment to UKCA marking documentation and final account.

Review the Tender Package and Establish Your Scope

Before putting a number to anything, read the entire tender package. Structural steelwork tenders typically include structural drawings and calculations, a specification (often based on the National Structural Steelwork Specification, 6th Edition), a construction programme, and conditions of contract. Read all of them before starting any take-off.

The first question to settle is scope. Are you pricing supply-only, supply and erect, or a design and build package? Each changes your risk profile significantly. A supply-only contract puts logistics and programme risk on the main contractor. Supply and erect means you own the crane coordination, the erection crew, and the erection programme. A design and build appointment adds connection design liability and professional indemnity exposure on top.

Next, confirm the Execution Class. Most commercial construction projects fall under EXC2. Projects with higher structural consequence - long-span transfer structures, heavily loaded frames, or buildings where structural failure would affect large numbers of people - require EXC3. Your UKCA certification level must match or exceed the Execution Class specified. If your certification covers EXC2 only and the specification calls for EXC3, declare that before pricing rather than discovering it after award.

Identify site-specific constraints early. Look at access route restrictions, crane availability and reach, congested city-centre delivery logistics, restrictions on working hours, and proximity to existing structures. A project with straightforward access and a dedicated mobile crane reduces erection costs significantly compared to a congested urban site where deliveries are restricted to overnight slots. Both projects may appear identical on the drawings, but the costs are not.

Finally, check whether fire protection is in your scope. If the specification requires intumescent coatings, establish whether these will be applied in the workshop or on site. Workshop application gives you better quality control and removes a weather-dependent task from the site programme.

Complete the Quantity Take-Off and Build Your Estimate

The take-off is the engine of your estimate. Work through the structural general arrangement drawings and section schedules systematically, recording every member by section designation, length, and weight. Group by element type: columns, primary beams, secondary beams, bracing, purlins, edge beams, and miscellaneous items such as kickers, base plates, holding-down bolts, and cast-in fixings.

The weight of a steel frame varies considerably by building type. According to SteelConstruction.info, a low-rise industrial building with wide bays and simple loading can run to around 40 kg per square metre of gross internal floor area (GIFA). A multi-storey city centre office, where the structural engineer specifies longer-span beams to maximize usable floor space, can reach 90 kg/m² GIFA or more. Understanding where your project sits on that range is a useful early sense-check on whether your take-off total looks right before you start pricing.

Once you have your weight schedule, price each cost component separately: steel material at current market rates, fabrication (cutting, drilling, welding, connection plates), workshop surface treatment (shot blast and primer for most projects; intumescent paint where fire protection is in scope), transport, and erection labour including crane costs. If you use sub-contractors for concrete decking, precast staircases, or cold-rolled purlins, price those as separate cost lines with their own margin.

Connection costs are consistently under-estimated at tender stage. Splice connections, moment connections, and base plates carry higher fabrication cost per tonne than simple cleated beam connections. If the drawings show a transfer structure, a Vierendeel frame, or a complex roof truss, the fabrication rate per tonne is higher and erection is slower. Build these items into a separate take-off line rather than absorbing them into an average rate.

Add your preliminaries: site management time, plant hire or crane coordination costs, personal protective equipment, fuel and transport logistics, and any required temporary works design for the erection sequence. Include a well-reasoned contingency for foundation interface items or base plate setting-out allowances that may be needed once you reach site.

Prepare and Submit Your Tender

Structure your submission clearly. A bill of quantities that shows tonnes by element type and your rates for fabrication, coatings, and erection tells the main contractor exactly what they are buying. It makes your submission easier to evaluate against competitors - which works in your favour if your price is well-reasoned and your programme is realistic.

Include a programme with your submission. Show when you need design information confirmed, when fabrication starts, when you plan first deliveries on site, and when erection completes. Main contractors build their master programme around the steel erection sequence, since it is typically a critical path activity. A programme that ties dates to design information milestones demonstrates that you understand how project risk flows.

State your assumptions explicitly. If the drawings you priced against are issue status C and you expect them to develop, note that in your submission. If your price assumes the main contractor provides the tower crane, write it down. If you are tendering for supply and erect and the main contractor asks you post-tender to include metal decking or precast stairs, that is a change in scope, not a clarification, and your price should reflect that.

Provide your BCSA membership details or UKCA marking certification evidence. Main contractors and clients have a duty to confirm that fabricators comply with BS EN 1090-1, the UK designated standard covering fabricated structural steelwork. Providing your certification upfront - including your Execution Class capability - avoids queries once you are appointed and demonstrates that you understand the compliance landscape.

From Contract Award to Fabrication Start

Once awarded, the critical path starts. Your first task is agreeing the full fabrication and erection programme with the main contractor: GA drawing approval dates, steel section procurement lead times, fabrication completion by element group, and on-site delivery sequence. Standard steel sections from UK stockholders typically carry lead times of two to six weeks. Less common profiles and heavy sections take longer. Build these lead times into your programme before you commit to erection dates.

Develop detailed fabrication drawings using your detailing software based on the approved GAs and connection designs. Where you carry design and build responsibility, have your connection calculations reviewed by a qualified structural engineer before issue for fabrication. These drawings are the basis for every component manufactured in your workshop and carry quality assurance obligations under BS EN 1090.

In the workshop, transfer electronic data to the fabrication line. Components are produced, marked with unique erection marks, drilled, assembled, and inspected. Apply surface treatment - primer, or intumescent coatings where the fire protection specification requires it - in the controlled workshop environment before transport. Workshop-applied coatings are more consistent, easier to inspect, and avoid the weather-dependent problems of on-site application.

Plan transport logistics around the erection sequence. Steelwork is delivered to site in erectable lots: each load corresponds to a defined portion of the frame in the order it will be erected. Coordinate delivery slots with the main contractor's site team on a week-by-week basis. An early delivery with no crane available creates a storage and handling problem on a busy commercial site. A late delivery stops the erection gang and, on a tight programme, generates delay notices quickly.

Erection Programme and Site Management

Submit your method statement and Risk Assessment and Method Statement (RAMS) to the main contractor before erection begins. The RAMS covers the erection sequence, crane lift plans, exclusion zone management, edge protection arrangements, connection procedures, and temporary frame stability during erection. It is not a form-filling exercise - it drives how the gang runs the job on site.

On site, work to your phased erection programme. Most commercial frames are erected bay by bay, working from the most stable portion outward. As each bay is plumbed and aligned, connections are completed: high-strength bolted connections are torqued to specification, and any site welds follow the project weld procedure specification. Do not allow the gang to progress to the next bay until connections in the current bay are complete and inspected.

Maintain a daily site diary. Record weather conditions - high wind stops crane lifts and is a recognized delay event under most forms of contract - gang size, members erected, and any instructions received from the main contractor. If the main contractor asks you to re-sequence erection to accommodate another trade, record the instruction and its programme impact in writing the same day. Programme changes that reduce erection efficiency are a compensable event, and you will need that record if disruption is raised later.

If base plate setting-out is outside tolerance when you arrive on site, do not proceed without agreement on remedial action. Steelwork that starts out-of-line propagates geometric errors through every subsequent bay, and correction at the top of a frame costs significantly more than correction at the base.

Final Inspection, UKCA Documentation, and Handover

Before standing down from site, complete your inspection and close-out process. Walk the completed frame and compile your snagging list: missing or under-torqued bolts, incomplete weld runs, damaged coatings requiring touch-up, and any items the main contractor's clerk of works has already noted. Resolve these before the main contractor walks the frame formally, rather than responding to a defect notice after your crew has stood down.

Prepare your as-erected drawings. Where site conditions required minor deviations from the fabrication drawings - a hole relocated, a plate adjusted to accommodate a foundation discrepancy - record each change. As-erected drawings are a contractual deliverable on most steelwork sub-contracts and form part of the building's O&M documentation, particularly important for any future structural alteration or renovation.

Collate your UKCA marking documentation. All fabricated structural steelwork delivered to site in Great Britain must be UKCA marked against BS EN 1090-1. Your declaration of performance records the Execution Class, the steel grades used, and any project-specific test results. Bring together material test certificates for the steel sections, weld inspection records, non-destructive testing results where specified, and surface treatment application records. The main contractor needs this documentation to satisfy the building control process and, on Building Safety Act-notifiable projects, the Building Safety Regulator.

Issue your final invoice in line with the payment schedule agreed in the sub-contract. If the contract includes retention, track the defects liability period (DLP) and issue your retention release request at the contractual date with a formal written notice. Retention held on completed steelwork packages represents a common cash flow problem for specialist contractors: on a sizeable package, even a small retention percentage can represent several weeks of working capital. Do not let the DLP expire without actively pursuing close-out in writing.

Commercial steelwork contracts reward contractors who are precise at estimate stage and organized through fabrication and erection. The margin on a steelwork package is built in at tender - what protects it on site is clear scope, a realistic programme, and tight cost tracking from the first delivery lot to the final account. Zigaflow helps steelwork contractors manage this process end to end: building multi-line quotes that break out sections, fabrication, coatings, and erection costs separately; raising purchase orders for steel sections and sub-trade packages; and invoicing against programme milestones. Book a demo at zigaflow.com/demo to see how it works for a structural steelwork business.

Sources

• Cost of Structural SteelworkSteelConstruction.info (BCSA & Tata Steel) · accessed 2026-07-15
• Structural Steel Estimating ServicesCOMET Estimating · accessed 2026-07-15
• UKCA Marking of Structural SteelworkSteelConstruction.info · accessed 2026-07-15
• Structural Steelwork Contractors UKBillington Structures · accessed 2026-07-15
• BHC Structural SteelworkBHC Ltd · accessed 2026-07-15

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