Get five subcontractors pricing off five different readings of the same package and the quotes that come back won't line up. One excludes the beads. One prices walls but not ceilings. One assumes you're supplying the materials. Comparing subcontractor quotes in that state isn't comparing prices at all. It's comparing assumptions.
A single bill of quantities fixes that before the enquiries even go out, because everyone prices the same measured scope.
Why comparing subcontractor quotes goes wrong
When you send drawings out to tender, each subcontractor reads them their own way. That's not bad faith. It's what happens when there's no single document saying what's included.
So each quote comes back with its own scope built in. Different quantities, different inclusions, different exclusions tucked into the small print at the bottom of page two. The lowest total looks attractive, but you've no quick way of knowing whether it's lower because the sub is efficient or because they missed a third of the job.
Levelling those quotes by hand is slow. You end up going back to each sub, asking what they've allowed for, adding back what they've left out, and building your own picture of the true comparison. On a tender with several packages and a tight deadline, that's days you don't have.
One scope, measured once
A bill of quantities measured to NRM2 sets out exactly what's being priced: each item described, with its quantity and unit. Instead of every sub interpreting the drawings, they price against the lines in front of them.
That shifts the question they're answering. Not "what do I think this job involves?" but "what's my rate for this item?" Rates are what subcontractors are good at. Guessing another firm's scope isn't.
It also cuts the work on their side. A sub who gets a bill doesn't have to spend a day measuring before they can put a number together, which means more of them actually return a price, and they return it sooner. The ones who were never going to bother measuring a speculative enquiry from scratch will often price a bill.
And it makes the package boundaries clear. Where does the groundworker stop and the bricklayer start? Who does the DPC, who fits the lintels, who makes good round the pipes? When those items sit in one package in the bill, they get priced once. When they're left to each sub's reading of the drawings, they tend to get priced twice or not at all, and neither of those shows up until you're on site.
If five subbies price five different scopes, the cheapest quote tells you nothing. Give them one bill and it tells you who's actually cheapest.
Comparing quotes line by line
When subcontractors price against the same bill, comparing their quotes line by line becomes straightforward. You can put the returns side by side and see where they differ.
Say three drylining quotes come back. Two are close on partitions but one is much higher on ceilings. That's a specific question you can ask about a specific item, rather than a vague sense that one total feels high. Maybe they've spotted something about access. Maybe they've made a mistake. Either way, you find out in a phone call rather than on site.
Before you accept any return, it's worth running through a few checks:
- Every line priced. Blank lines or items marked "included" elsewhere need an answer before the quote is comparable.
- Qualifications read. Check the covering letter for exclusions that quietly change the scope the bill set out.
- Rates in line. A rate far below the others on one item often means a misread description, not a bargain.
- Arithmetic checked. Quantities multiplied by rates should equal the totals shown. It's surprising how often they don't.
- Attendances clear. Who provides scaffolding, skips, welfare and power should be settled, not assumed.
It protects you when work changes hands
If a subcontractor drops out mid-tender, or a package needs re-pricing later because the first choice can't hold their price, a bill already measured means the replacement prices the same document. You're not starting the scope conversation from scratch with someone new while the deadline gets closer.
The same applies after award. When a variation comes in, the bill gives you a quantity and a rate to measure the change against. That's a far easier discussion than arguing about what the original lump sum was meant to include.
For smaller contractors this matters just as much as it does on big schemes, arguably more, since there's less margin to lose in a dispute. We've covered that side of it in what a bill of quantities does for a small contractor.
How we build a bill your subbies can price
We measure every element off your drawings to NRM2 and set out the bill so each trade package can be sent out on its own. Descriptions are written so a subcontractor can price them without phoning you to ask what's meant. Priced on current UK rates, it also gives you a benchmark to check each return against, so you know whether a quote is keen or suspicious before you rely on it.
Our bill of quantities services run on a fixed fee agreed before any work starts, and the bill is delivered in time for your tender deadline, so the enquiries go out with enough time for subbies to price properly.
A rule of thumb for your next enquiry
Before you send a package out, ask yourself whether two subcontractors reading your enquiry could reasonably price different amounts of work. If the answer is yes, comparing subcontractor quotes at the end will mean comparing guesses. Measure the scope once, send the same document to everyone, and let the rates do the talking.