Tendering and estimating, 29 October 2026
AI tendering for cladding and facade contractors
Price a cladding tender only after you know three things: whether the combustibility ban applies, who designs the system and its fixings, and what warranty the client expects. In England, materials in the external walls of residential buildings with a storey at 18 m or more must be class A2-s1, d0 or A1. Then price each layer, with design and testing as separate lines.
What makes cladding tenders hard to price?
Fire rules, design responsibility and the substrate. A facade package can look like a simple m² job on the drawings and carry six figures of risk in the spec and the contract.
The problems that come up on most cladding packages:
- Combustibility. Whether the building is caught by regulation 7, and whether every layer of the system meets the class required.
- Design responsibility. "Design, supply and install" packages make you responsible for the system, its wind loads and its fixings.
- Wind loads and fixings. Corner and edge zones need more brackets, and the substrate has to hold them.
- Remediation work. Replacing unsafe cladding on occupied buildings, with surveys, phasing and approvals.
- Warranties and insurance. System warranties, collateral warranties and professional indemnity cover for design.
Whatever I was bringing in, was paying out
He was running every job in one Excel sheet. On cladding work, where one package can be worth more than a month's turnover, not knowing the cost of each job until it's finished is how a busy year ends with nothing left.
Does the combustibility ban apply to this building?
Check where the building is, how high its top storey is and what it's used for. Those three answers decide which rule applies.
legislation.gov.uk, Building Regulations 2010 regulation 7; GOV.UK, Approved Document B June 2022 amendments; gov.scot, building standards changes June 2022
Materials that become part of the external wall or a specified attachment must be class A2-s1, d0 or A1. Exemptions include membranes, seals, gaskets, fixings, window frames and glass, and cavity trays between masonry leaves. Check every layer against the data sheets.
Approved Document B recommends A2-s1, d0 or better for external surfaces and for insulation and fillers. Building control will expect that or a justified alternative from the designer.
Scotland bans combustible materials in cladding on dwellings and other relevant buildings with a storey at 11 m or more. Wales has its own version of regulation 7. In Northern Ireland, check with the council's building control.
Approved Document B still sets reaction-to-fire guidance by height and use, and metal composite panels of the banned type can't be used on any building in England.
If the building is also a higher-risk building in England (18 m or 7 storeys, with two or more residential units, or a hospital or care home), most building work needs the Building Safety Regulator's approval before it starts. That includes much remediation work, so ask whether approval is in place and allow for it in the programme. On any building where the rules are unclear, get a fire engineer's view on the external wall before you price, and leave the final classification decision to the principal designer.
Who designs the system and the fixings?
Whoever the contract says, and on many cladding packages that's you. Read the scope for "design", "develop the design" or "contractor's design portion", because each one moves responsibility to you.
If you take design, you're responsible for the system meeting the fire class, the wind loads and the movement it has to take. That needs a competent designer, usually the system supplier's engineer or your own, and professional indemnity insurance. Ask whether the system supplier will produce wind load calculations and a fixing layout for its own system; the wind uplift and fixings guide explains how corner and edge zones change the bracket count.
The substrate is the other half. Brackets need to hold in whatever the wall is made of, so pull-out tests on site belong in the price, or the risk belongs to the main contractor in writing.
How do you price a 420 m² rainscreen package?
Price each layer per m² or metre, then design and testing as their own lines.
A 420 m² rainscreen package on a five-storey residential block, top storey at 14 m, England
Below 18 m, so regulation 7(2) doesn't apply, but the designer has followed Approved Document B guidance for 11 m and over: A2-s1, d0 panels and A1 mineral wool. Rates include margin and are illustrative.
| A2-s1, d0 rainscreen panels, supplied and fixed420 m² × £165 | £69,300 |
| Aluminium subframe and brackets420 m² × £38 | £15,960 |
| Mineral wool insulation420 m² × £21 | £8,820 |
| Cavity barriers at floors and openings180 m × £24 | £4,320 |
| Wind load calculations and fixing layoutsystem supplier's engineer | £2,400 |
| Pull-out tests on the substrate12 × £85 | £1,020 |
| Tender price | £101,820 |
Design and testing are only 3% of that price, and they're the lines most often missed. Without them you're either designing for free or pricing a fixing layout you haven't seen.
What should a cladding tender qualify?
Design, fixings, wind loads, warranties and the fire classification you priced. Put the biggest risks first.
Tender: project, external wall cladding package Our price: £amount excluding VAT, dated date Design and classification 1. Design responsibility: none, install only / system design by supplier, coordinated by us / full design. Our PI insurance: £amount each and every claim / aggregate. 2. System priced: manufacturer, system. Panels class A2-s1, d0, insulation class A1, as data sheets attached. Any substitution requires the designer's written approval. 3. Building height and use assumed as top storey height, use. Classification requirements confirmed by principal designer / fire engineer. Wind loads and fixings 4. Wind load calculations and fixing layout by system supplier's engineer, included. Changes to building geometry or exposure revalued. 5. Substrate assumed suitable for the fixings shown. Number pull-out tests included; additional tests or a change of fixing after testing are a variation. 6. Fixings into structure only where shown; no fixings into insulation / cladding zone / unsuitable substrate. Interfaces 7. Windows, doors, DPCs and roof edge details by others, fitted before cladding of each elevation. 8. Cavity barriers included at locations shown on drawing. Additional cavity barriers revalued. Warranties and access 9. Manufacturer's system warranty included / excluded. Collateral warranties on standard form only. 10. Scaffold, hoist, loading and storage by others.
Use the tender qualifications and exclusions template for payment, price validity and general attendances.
What can AI do on a cladding tender, and what can't it?
AI is good at reading long facade specs and cross-checking every layer against its data sheet. It can't take responsibility for a fire classification or a fixing.
What AI does well:
- Measures elevations by zone and panel type, with cavity barrier runs at floors and openings. See can AI do a take-off from drawings.
- Checks every layer's class against the data sheets and the building's height and use, and flags a combustible insulation or membrane the spec missed.
- Finds design responsibility wording in the scope, prelims and contract amendments.
- Drafts qualifications with the system, classes and drawing references filled in.
What still needs the cladding contractor:
- The substrate. Whether the wall will hold the brackets, which only a pull-out test shows.
- Buildability. Interfaces with windows, balconies and roof edges, and the sequence on site.
- Risk. Design liability, insurance and warranties you're willing to give.
- Sign-off. The fire classification is the designer's decision, and the price is yours.
How do you win more cladding tenders?
Show the client you understand the fire and design risk. On facade work, the bidder who sets out classes, design responsibility and testing clearly is easier to appoint than one who's cheapest.
- Attach data sheets for every layer you priced.
- State design responsibility in line one, not line twenty.
- Price testing and design openly.
- Read the pack first with the 10-minute tender read and drop any you can't insure.
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 cladding tenders, Nexley reads the pack you forward on WhatsApp, measures elevations and cavity barrier runs, checks every layer's fire class against the building's height and use, and drafts a priced schedule with design, testing and warranty qualifications. You check the substrate and the design scope and approve the price.
Common questions
What is regulation 7(2)?
The rule in the Building Regulations 2010 that bans combustible materials in the external walls of relevant buildings in England. A relevant building has a storey at least 18 m above ground and contains dwellings, an institution or a room for residential purposes. Materials must be class A2-s1, d0 or A1, with listed exemptions.
Does the ban apply below 18 m?
Not the ban itself in England. But Approved Document B recommends A2-s1, d0 or better for external surfaces and insulation on residential buildings with a storey at 11 m or more, and Scotland bans combustible cladding at 11 m.
Do I need PI insurance to tender cladding?
If the package includes any design, yes. Design and build or contractor's design portion makes you responsible for the system, so check the level of cover the tender asks for before you bid.
Who checks that the cladding is compliant?
The designer specifies it and building control checks it. On a higher-risk building in England, the Building Safety Regulator approves the work. Your job is to install exactly what's approved and keep the records.
Sources
- legislation.gov.uk: The Building Regulations 2010, regulation 7
- GOV.UK: Approved Document B, June 2022 amendment booklet
- gov.scot: Building standards technical handbooks 2022, summary of changes
- GOV.UK: Building control approval for higher-risk buildings
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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