Subcontractor Bid Comparison: How to Compare Quotes Properly

"Just get three prices and go with the cheapest."

If you've been in construction for any length of time, you've heard this. And if you've followed this advice, you've almost certainly been burned by it.

Subcontractor bid comparison — doing it properly — is one of the most commercially significant tasks on any project. Get it right and you've locked in competitive pricing from capable firms who'll deliver. Get it wrong and you've appointed the cheapest bidder who excluded half the scope and will spend the next six months submitting variations.

The Problem With Simple Price Comparison

Three subcontractors price the same package. One comes in at £120,000, one at £145,000, one at £180,000. The obvious choice is £120,000, right?

Not necessarily. Until you understand what's included in each price, you're comparing apples to oranges. The £120,000 quote might exclude:

• Builders work in connection
• Out-of-hours working
• Making good after their installation
• Testing and commissioning
• Attendance on other trades
• Protection of finished work
• Waste removal
• Insurance and warranties

Once you add back the exclusions, that £120,000 price might actually be £155,000. Now the £145,000 quote — which included everything — is the cheapest compliant bid.

This happens constantly. And the larger and more complex the package, the more scope there is for pricing variations to hide significant cost differences.

Building a Proper Comparison

Here's the process I use on every subcontract package:

Start with a clear tender enquiry. The quality of your comparison depends entirely on the quality of your enquiry. If you send vague scope descriptions and incomplete drawings, you'll get vague prices that are impossible to compare. Send a proper tender package: scope of works, relevant drawings, specifications, programme, preliminaries requirements, form of subcontract, and any employer's requirements that flow down.

Use a structured pricing document. Don't let subcontractors price on their own letterheads in their own format. Provide a pricing schedule or bill of quantities that requires them to price against the same items. This forces a like-for-like comparison and makes it immediately obvious when someone has priced an item significantly differently.

Create a comparison spreadsheet — or use a tool that does it for you. Line up the returns side by side, item by item. Flag any items where one price is significantly higher or lower than the others. These anomalies tell you something — either one contractor has spotted a risk the others haven't, or one has misunderstood the scope.

List inclusions and exclusions. Every subcontractor return should come with a list of what's included and what's excluded. Map these against your requirements. If your scope requires testing and commissioning and the subcontractor has excluded it, you need to price that back in.

Adjust to a common basis. Once you've identified all the exclusions, qualifications, and anomalies, adjust each price to a common basis. This is your "apples to apples" comparison. The adjusted figures are what you should be comparing, not the headline numbers.

Consider the qualitative factors. Price isn't everything. For critical packages — structural steel, M&E, facades — the subcontractor's track record, resources, and financial stability matter enormously. A firm that's £10,000 cheaper but has a history of late completion on similar projects is a false economy.

The Red Flags

Here are the returns that spell trouble:

Significantly lower than the estimate and other returns. If your estimate is £150,000, two returns are at £140,000 and £155,000, and one comes in at £95,000 — something is wrong. Either they've misread the scope, they're buying the job at a loss (which creates its own problems), or they've excluded significant elements.

Heavy qualifications. "Subject to final design information." "Provisional allowance for builders work." "Price based on uninterrupted access." These qualifications are escape hatches. If the final price ends up 30% above the tender because every qualification triggered an adjustment, the tender comparison was meaningless.

No breakdown. A lump sum with no supporting detail is impossible to evaluate properly and makes post-contract administration — valuations, variations, final accounts — extremely difficult. If a subcontractor won't provide a breakdown, ask yourself why.

Unrealistic programme assumptions. A price based on completing the M&E first fix in three weeks when every other subcontractor has priced four to five weeks suggests either an under-resourced bid or a misunderstanding of the scope.

After the Comparison

The comparison doesn't end with selecting the cheapest adjusted price. Before you appoint:

Clarify any remaining ambiguities. If there are items where the pricing seems inconsistent or the scope coverage is unclear, arrange a post-tender interview. Go through the return line by line if necessary. It's far better to resolve these questions before appointment than after.

Negotiate, but fairly. There's nothing wrong with negotiating — but shopping one subcontractor's price to another to drive down the cost is poor practice, damages trust, and catches up with you eventually. Negotiate on genuine issues: scope clarification, programme alignment, payment terms.

Document the agreed scope. Whatever you agree, get it in writing. The subcontract order should clearly reference the drawings, specifications, and any post-tender clarifications. Ambiguity at this stage becomes a variation at the next.

Why This Matters More for Small Contractors

On a £2m fit-out, your top three or four subcontract packages probably account for 50-60% of the total project value. Getting the right M&E contractor, the right partitioning contractor, and the right ceiling contractor at the right price isn't just a commercial exercise — it determines whether the project is profitable or not.

Large contractors have procurement departments that do this all day. Small contractors are doing it in between site visits, client meetings, and the hundred other things that fill the week. That's why having a systematic approach — and ideally, tools that streamline the comparison — makes such a difference.

We built Construction AI's tender comparison tool specifically for this — subcontractor management software that handles the comparison mechanics so you can focus on the decisions. Upload the returns, map them against your pricing schedule, and the system highlights the variances, exclusions, and anomalies automatically. Combined with AI-powered analysis, it doesn't replace commercial judgement, but it dramatically reduces the time spent on the comparison mechanics so you can focus on writing tenders that win.