AI tendering for groundworkers and civils contractors

Price a groundworks tender from the bill of quantities or your own take-off: excavation by bank volume, cart away by loose volume after bulking, then concrete, drainage and attendances, each with its plant, labour and tipping costs. Then settle who carries the ground risk. AI can check the bill and the volumes quickly; you judge the ground.

What makes groundworks tenders hard to price?

Most of the cost is underground and not on the drawings. A groundworks package from a main contractor usually comes with a bill of quantities, a drainage layout, foundation details and a site investigation report, if you're lucky. The bill tells you the quantities. It doesn't tell you what the ground will do.

The problems on most groundworks tenders:

• Bulking. A cubic metre in the ground is more than a cubic metre in the lorry.
• Spoil classification. Inert, non-hazardous or contaminated, each with a different tipping cost.
• Unknown ground. Soft spots, obstructions, water, deeper foundations than drawn.
• Buried services. Not always shown, always your risk if you hit them.
• Attendances and access. Haul roads, wheel wash, welfare and who provides them.
• Payment and retention. Long terms, retention and pay-when-paid wording on a cash-heavy trade.
• Paperwork. RAMS for excavations and confined spaces, and CIS on your own subbies.

A groundworks firm on paper is pricing every bill line, chasing every supplier and writing every RAMS by hand. The pricing method below works on paper too, but the arithmetic is exactly the part worth handing over.

How do you price dig and cart away?

Measure the excavation in the ground (bank volume), then apply a bulking factor to get the loose volume you're carting. Price lorry loads on the loose volume, never the bank volume.

Published bulking figures put clay at 20 to 40%, sand and gravel at 20 to 30%, and rock at 40 to 80%. Use the site investigation to pick the figure, and use the top of the range when the ground is wet clay or the report is thin.

Price those inspections, trench support and service location into the job: they're time on every shift. For deep manholes and chambers, see confined space work for groundworkers.

Who carries the ground risk?

Whoever the contract says, and on many subcontracts that's you unless you qualify it. Look for wording that you're "deemed to have satisfied yourself" about ground conditions, and check whether a site investigation report is in the pack.

What should a groundworks tender qualify?

Ground conditions, spoil, water and services, first. Then attendances and payment.

Tender: project name, groundworks package
Our price: £amount excluding VAT, dated date

Ground
1. Price based on site investigation report reference. Conditions differing from the report will be valued as a variation.
2. Excavation in ground type, assumed free of obstructions, old foundations and soft spots. Breaking out and extra depth at £rate per m³.
3. Foundations priced to depths shown on drawing. Additional depth instructed by building control at our schedule rates.

Spoil
4. Cart away priced as inert spoil to licensed tip. Non-hazardous, contaminated or hazardous spoil, testing and classification excluded.

Water
5. Dewatering beyond pumping from excavations with number submersible pumps excluded.

Services
6. Existing services located and marked by others before we start. Diversion, protection and damage to unrecorded services excluded.

Site
7. Haul roads, wheel wash, welfare and security by the main contractor unless listed.

Payment
8. Monthly applications; payment within number days. Retention not accepted / accepted at x%, half released at practical completion.
9. VAT and CIS applied as required by HMRC. CIS deducted from labour only, not from materials or plant hire we pay for directly.

On payment, a clause making your payment conditional on the main contractor being paid by the client is ineffective under section 113 of the Housing Grants, Construction and Regeneration Act 1996, unless the party upstream is insolvent. Northern Ireland has its own construction contracts legislation, so check it there. For the wider picture, see main contractor payment terms.

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

AI is good at checking the bill and doing the volumes; it's no use on what's under the topsoil.

What it does well:

• Checking the bill. Recomputing volumes from the drawings and flagging quantities that don't match.
• Bulking and loads. Turning bank volumes into loose volumes and lorry loads.
• Reading the SI report for water levels, made ground and contamination flags.
• Drafting qualifications and RAMS starting points from your standard documents. See can AI write RAMS.

What still needs you:

• The ground. What the report means on this site, and how much to allow.
• Plant and method. Which machine, how many days, where the spoil goes.
• Risk pricing. Whether to carry the ground risk and for how much.
• Sign-off on the price and the qualifications.

Which groundworks tenders should you bid?

The ones with a site investigation, a clear bill and payment terms your cash can carry. Use the 10-minute tender read and walk away from packs with no SI report and a "deemed satisfied" clause, or a retention and payment term that would leave you funding the job. For how Nexley works for groundworks firms more widely, see the groundworks and civils trade page.

Common questions