Five subcontractors price the same job. One includes the cavity closers, one doesn't. One reads the external works as a provisional sum, two measure them, and the last leaves them out altogether. By the time the prices come back you're comparing five different jobs, not five prices for one. That's the problem bill of quantities services exist to solve: one measured document, one scope, and everybody pricing against it.
What a bill of quantities actually is
A bill of quantities (BoQ) is the job broken down into measured items. Each line describes a piece of work, gives a unit and states the quantity. Brickwork in square metres. Concrete in cubic metres. Skirting in linear metres. Doors counted as numbers. Then there's a rate column and a total column, which whoever is pricing fills in.
It isn't the same as a takeoff, though it's built from one. The takeoff is the measuring. The bill is how those measurements are organised, described and presented so that somebody else can price them. If you want the whole chain, we've written about how your takeoff, BoQ and estimate should line up.
Who writes it varies. On larger, traditionally procured jobs the client's QS usually issues a bill with the tender documents, and every contractor prices the same one. On smaller jobs there often isn't a bill at all. You get a set of drawings, maybe a specification, and a return date. Everybody measures for themselves, which is exactly where the scope starts to drift between prices. That gap is what a BoQ preparation service fills for contractors and builders who don't have a bill handed to them.
What bill of quantities services should hand back
When you pay for BoQ preparation you should get more than a spreadsheet of numbers. A proper bill includes:
- Every element measured off the drawings, not estimated from a floor area.
- Clear item descriptions, so the person pricing knows exactly what the line covers (material, thickness, finish, fixing).
- Consistent units of measurement throughout.
- Items grouped by work section, so a trade can find its package without reading the whole document.
- Preliminaries, provisional sums and PC sums kept separate from the measured work.
- A list of the drawings and information it was measured from, plus the assumptions made where the drawings weren't clear.
That last point gets skipped more often than it should. If the bill doesn't say which revision of the drawings it was measured from, you can't tell later whether a change is a genuine variation or something that was always shown.
Our bill of quantities services measure every element off your drawings to NRM2 and, if you want it, price the bill on current UK rates local to the job. The fee is fixed and agreed before we start. You can see the finished document in our sample estimate, takeoff and BoQ.
Why an NRM2 bill of quantities is easier to trust
NRM2 is the RICS set of rules for detailed measurement of building works. It sets out how each type of work is measured, what an item includes, and how the bill is split into work sections.
Why should a builder care? Because it takes the guesswork out of reading someone else's bill. When a bill follows NRM2, a blockwork line means the same thing to you, your subcontractor and the client's QS. Nobody has to wonder whether the rate is meant to cover the mortar, the ties or the cutting. The rules settle it.
It makes checking easier too. If every item is measured the same way, you can pick any line, go back to the drawing and check the quantity yourself, which is the whole point of a bill you can rely on. There's more on that in what's inside your bill of quantities and why you should be able to check every line.
A bill of quantities for tender: one scope for every trade
This is where a BoQ earns its money.
Without one, every subcontractor and supplier does their own measure. Each counts slightly differently and each makes different assumptions about what's in and what's out. The prices come back looking comparable. They aren't. And the cheapest one is often cheapest because it's missed something.
With a bill, every price is against the same measured quantities and the same descriptions. If one groundworker comes in well under the others, you can see exactly which lines are low. Maybe they've found a better method. Maybe they've misread the drawing. Either way you can ask, line by line, before you put their number in your tender. We've gone through how that works on a real package in a bill of quantities every subcontractor prices from.
It protects you after the tender as well. Once the job is running, the bill is the baseline. A variation gets measured against it. An interim valuation can be checked against it. Without a bill, every change turns into an argument about what was in the original price, and small builders tend to lose those arguments because they can't prove their scope.
One more thing. A bill shows gaps quickly. If the drawings don't say what the floor finish is, the measurer has to write that down as a provisional item or an assumption. You then see it before you tender, rather than finding out on site.
When it's worth paying for a BoQ
Not every job needs a full bill. A small repair or a single trade package can be fine off a measured schedule. Using bill of quantities services makes more sense when:
- You're sending the job to several subcontractors and need to compare their prices fairly.
- The client or their QS has asked for a priced bill with your tender.
- The job is big enough that one missed line would really hurt.
- You expect changes on site and want a clear baseline to price them against.
You also need to decide whether you want the bill priced or left blank. An unpriced bill is what you send out to subcontractors and suppliers, so they fill in their own rates. A priced bill, with rates from current UK costs already in, gives you a checked figure to compare their returns against. Plenty of builders want both: the blank version to issue, and the priced one kept back as their own benchmark. Either way, the quantities underneath are identical, which is the point.
If a couple of those describe your next job, that's what our BoQ preparation is set up for. And the earlier the bill exists, the fewer arguments you'll have once the job is on site.