AI tendering for plasterers and renderers

Price a render tender per m² of each render system, built from your gang's day cost and output, the system's materials with waste, and your margin. Then price beads, reveals, masking and weather protection as separate lines. Before you price, check the spec names a system whose warranty needs an approved installer, because that decides whether you can bid at all.

What makes plastering and render tenders hard to price?

The drawings give you elevations; the spec decides what each m² costs. A render package on a new block of flats might carry a silicone thin coat on blockwork, a different system on insulation, and a brick slip band, each with its own basecoat, mesh, primer and beads.

The problems that come up on most render packages:

• System warranty. The spec names a manufacturer's system, and the warranty is only issued if an approved installer applies the whole system as specified.
• Beads and details. Corner beads, bellcast beads, stop beads, movement beads and window reveals take more time than the flat wall.
• Weather. Thin-coat renders have tight application windows. Rain, frost and heat stop work, and wet days still cost you the gang.
• Scaffold by others. Your output depends on the scaffold being adapted, sheeted and clear of other trades when you need it.
• Background. Existing render that has lost its bond, out-of-tolerance blockwork and damp walls all need work before your system goes on.
• Internal plastering carries its own risks: board versus wet plaster, drying times and making good after services.

How do you price a 650 m² render package?

Measure net area for each system, price it per m² from your gang's cost and output, then add the linear items and the allowances the drawings don't show.

Two checks before that price goes out. First, the bag count. One silicone render data sheet gives about 8 to 10 m² per 25 kg bag for a 1.5 mm finish, so 650 m² plus 10% waste needs between 72 and 90 bags. A take-off that lands far outside that range has a wrong area or a wrong coverage figure.

Second, the weather. The margin inside the render rate is £7.22 a m², or about £4,693 across 650 m². Four days lost to rain with the gang paid costs £2,880, which is 61% of that margin. Price a weather allowance or qualify the time, and see converting a day rate to a price per m² for the method behind the rate.

Do you need approved-installer status to bid?

Often, yes, if the spec names a manufacturer's system and asks for its warranty. The warranty is the manufacturer's, and it sets the conditions: who applies it, where materials come from, and whether the work is inspected.

Two real examples of how this works. One render manufacturer's approved programme asks applicators to hold at least one of its accreditation certificates, says the whole system must be specified and supplied by the manufacturer, and inspects the finished work before it issues a five-year crack-free guarantee. Another lists 10 and 25 year material warranties when an approved installer fits its silicone system, and says the approved installer must carry out a pre-installation survey.

On taller residential buildings, the external wall is also a fire question. In England, materials in the external walls of a building with a storey at 18 m or more containing dwellings must meet class A2-s1, d0 or A1, so a render on combustible insulation may not be allowed at all. See AI tendering for cladding and facade contractors for how that rule works.

What should a render tender qualify or exclude?

Everything your rate assumes that the main contractor controls: the scaffold, the background, the weather, the programme and the warranty. Tie each line to a drawing, elevation or spec clause.

Tender: project, external render package
Our price: £amount excluding VAT, dated date

Basis of price
1. Priced from elevations drawing numbers and revisions and render specification clause, revision.
2. System priced: manufacturer and system name, applied as the manufacturer's current data sheet. Any change of system will be revalued.
3. Manufacturer's warranty: included, as approved installer / not included. Warranty depends on the manufacturer's inspection and on payment in full.

Weather
4. Render will not be applied below 5°C, in rain, or when frost is forecast, as the manufacturer's data sheet requires. Time lost to weather is an extension of time, not at our cost.
5. Weather protection included: sheeting and heaters as listed / none. Additional sheeting or heating charged at cost plus x%.

Scaffold and access
6. Scaffold, adaptations, sheeting and loading bays by others, erected and inspected before we start each elevation, with boards at the required lifts and clear of other trades.
7. Number visits assumed. Additional visits caused by others at £rate per visit.

Background and making good
8. Background assumed sound, clean, dry and within the manufacturer's tolerance. Hacking off, dubbing out over 10 mm, or bond repair to existing render are excluded unless listed.
9. Window and door frames, sills and copings fitted by others before we start, and sills projecting beyond the finished render face.
10. Making good around services, fixings or brackets installed after our work is excluded.

Payment
11. Monthly applications for payment, payment within number days. Retention not accepted / x%.

For wording on the general lines (price validity, design, attendances), use the tender qualifications and exclusions template and delete what doesn't apply.

What can AI do on a render tender, and what can't it?

AI tendering tools are good at the reading and measuring. They're poor at anything you only learn by standing in front of the wall.

What AI does well on a plastering or render tender:

• Reads the whole pack. Spec, elevations, prelims and the subcontract order, and pulls out the named system, warranty clauses, scaffold arrangements and programme.
• Measures from elevations. Gross and net areas per elevation and per system, opening counts, and bead runs by type. See can AI do a take-off from drawings for where measuring works and where it doesn't.
• Spots spec clashes. A render specified on a board the data sheet doesn't list, a bead that isn't part of the named system, or an adhesive that doesn't suit the insulation.
• Drafts qualifications from your standard list, filled in with the drawing numbers and spec clauses.

One roofing and cladding firm in Ireland, eight workers, had a tool flag a non-compliant adhesive on XPS board and correct the board coverage from 0.75 to 1.44 m² per board. A coverage figure that wrong would almost double the board order, and it's the kind of thing that only shows up when every line is checked against a data sheet.

What still needs the plasterer:

• The background. Whether old render is sound, how far the blockwork is out, and how much dubbing out it needs.
• Output. How many m² your gang gets through on this building, with these details and this scaffold.
• Weather and season. A March start on a north elevation isn't a July start.
• Risk and sign-off. How much to allow, what to qualify and whether to bid.

How do you win more render tenders without cutting the rate?

Bid the work you're set up for and make your price easy to compare. Main contractors choose between three or four render subbies, and the one with a clean, specific schedule and the right approved-installer status is easier to appoint.

• Bid where you hold the approval. Being on the specified manufacturer's list removes a reason to reject you.
• Price the system as specified, and offer savings as a separate alternative.
• Show your bead and detail take-off. It proves you've read the elevations and protects you when details are added later.
• Read the pack in ten minutes first using the 10-minute tender read, and drop the ones you can't win.

Fit-out and finishing trades can see how Nexley handles this work on the fit-out trade page.

Common questions