A commercial decision dressed as a technical one
Every project has to answer one question about measurement: whose numbers are the contractual ones. There are three usual answers. The employer measures and issues a bill of quantities. The contractor measures from the employer’s drawings and prices their own quantities. Or the works are remeasured as built.
Each of those allocates risk differently, and the allocation is worth more than the measurement itself. Where the employer’s quantities govern, an error in them is the employer’s risk. Where the contractor’s govern, it is theirs, and they will price for that.
The decision is frequently taken by default, by choosing a procurement route without anybody articulating the measurement consequence that comes attached to it.
The question is separate from who does the measuring. A contractor can measure the works while the employer’s bill remains the contractual basis, and an employer can have quantities checked without those quantities governing anything. Ownership is about which set of numbers the contract points at when there is a disagreement, and only the contract answers it.
What each route means in practice
A bill of quantities prepared for the employer gives you a common basis for comparing tenders, a document for valuing change, and a defined risk sitting with you if the quantities are wrong. It costs money to produce and it earns that back at the first significant variation.
Contractor measured quantities move that risk across and remove your comparison basis, because every tenderer has measured differently and you are no longer comparing like with like. That is manageable on a simple scheme and difficult on a complex one.
Remeasurement suits work whose extent genuinely cannot be known in advance, and it removes cost certainty in exchange, which we covered in remeasurement contracts.
There is a cost to preparing quantities and it is knowable in advance, which is what makes it easy to cut. The cost of not having them is unknowable in advance and arrives spread across every variation for the length of the contract, which is what makes it easy to ignore. Those two facts together explain most of the decisions taken on this point.
The default that catches people
On design and build the contractor takes responsibility for design and, with it, usually for quantity. Developers often read that as the risk having gone away. What has actually happened is that the risk has been priced and included, and the price of it is invisible because it sits inside a lump sum.
That is a fair trade when the employer’s requirements are tight. Where they are loose, the contractor has priced a quantity risk against a scope they were entitled to read narrowly, and the difference emerges as change.
Checking without duplicating
Where the contractor’s quantities govern, checking them can look like paying twice. It is not, because the exercise is not a full remeasure. It is a targeted test of the elements that carry the most value and the most measurement risk: substructure, frame, envelope and the items priced at high rates.
A partial check of that kind establishes whether the measurement is broadly sound and finds the outliers, which is what matters commercially. We set the method out in tender quantity verification.
Where it surfaces later
Quantity disputes rarely appear during construction. They appear at remeasurement or at the final account, when the works are built and the options are limited to argument.
By then the question is not what the correct quantity was. It is what the contract said about whose quantity governed, and whether the records exist to show what was actually built. Our scenario on quantity assumption risk describes how that plays out.
What this means for you
Decide the measurement basis deliberately, at the point of choosing a procurement route, and write down which party carries quantity risk. That one sentence prevents a large category of argument.
If your scheme is running on quantities nobody independent has looked at, a targeted check now costs a fraction of what the same exercise costs once it is contested. That is the work described on our quantities and take-off and client side quantity surveyor pages.
Whichever route is chosen, write it into the tender documents in plain terms rather than leaving it to be inferred from the contract form. Tenderers price what they understand, and a document that leaves quantity risk ambiguous will produce bids that have priced it differently from each other, which makes the comparison meaningless before it has begun.