The role of a quantity surveyor at each stage of the project
The role of a quantity surveyor runs through the whole project: a quantity surveyor is an engineer or a registered building technician, like Yaakov Avital, who supports a construction project from the stage when there are only first drawings through to the final account. At each stage the quantity surveyor answers a different question: how much the project is likely to cost, what exactly is being priced, how much has been built and how much the contractor is owed.
This guide goes through the role of a quantity surveyor in the order of the project. For each stage you will find the deliverable, who uses it, and what to ask for now so that the numbers still hold at the next stage.
The role of a quantity surveyor at the design stage: early estimate and change control
At the start of design there are no details yet, but there are areas, a number of floors and an outline specification. On that basis a preliminary cost estimate is built, and the design is checked against the budget. As the design progresses, the estimate is updated and becomes more detailed. How this is done and what the estimate includes are covered in the guide to construction cost estimates.
At this stage it also matters to track versions. Every new design version changes quantities. So every quantity is recorded with its source and its date, and when a new version arrives, the items that changed are marked, together with how much they changed. Whoever receives the document sees at once what moved and does not have to guess.
Tender stage: the bill of quantities and bid comparison
Before contractors are approached, the quantities are arranged in a bill of quantities (BOQ) by chapters, phases and items. The structure follows the contracting model: one main contractor, direct subcontractors, or management on behalf of the client. When the work goes to subcontractors, each chapter becomes a closed package with clear scope boundaries, and the shared site costs are shown separately.
On a project with consultants, the BOQs for electrical, HVAC, plumbing and fire protection also need to go into the tender documents. At this stage you can also order, as a separate service, the inclusion of these BOQs in the tender documents as they are, without any change to their content, so that the contractors receive one orderly set of documents. The professional content remains the consultants' responsibility.
When the bids come back, they all refer to the same items, and you can compare them line by line. A large gap in one item is a sign to check whether the contractor understood the description differently. It does not necessarily mean that the bid is expensive.
Construction stage: payment applications, measurements and variations
During construction the contractor submits interim payment applications for the work done. A quantity surveyor on the client's side checks them against the bill of quantities and against what was actually built; on the contractor's side, the quantity surveyor prepares the applications and backs up every line. Work that did not appear in the original bill is reviewed under the terms of the contract, and if it is recognised as a variation, it is priced and documented separately.
I came to know this side of the role closely in the years I worked as an estimator and quantity surveyor with a main contractor, on multi-storey residential building, tenders, payment applications and variations. Someone who has prepared a payment application for a contractor knows which BOQ items create arguments, and so writes them clearly from the start.
Project close-out: the final account
At the end of the project all the payment applications, variations and measurements are brought together into a final account. This is where documentation from the start shows its value. When every quantity has a source and a date, and every change has an explanation, agreement is easy to reach. When they do not, every item is open to argument.
On projects with identical buildings or repeated floors, it is worth deciding already at the tender stage how the repetition will be presented. When the identical building and the typical floor are each presented separately, it is clear what was measured once and what was multiplied, and this usually reduces arguments over the final account.
| Stage | The question | The deliverable |
|---|---|---|
| Design | How much is it likely to cost, and is it within budget? | A preliminary cost estimate and version tracking |
| Tender | What exactly is being priced? | A bill of quantities, subcontractor packages and bid comparison |
| Construction | How much has been built, and what has been added? | Checking payment applications and variations against the bill |
| Close-out | How much is owed in total? | A documented final account |
Who hires a quantity surveyor, and why
- A developer or client: to build a budget, go to tender on a uniform basis and compare bids.
- A contractor: to check quantities before submitting a bid, break the work into subcontractor packages and prepare payment applications. Details on the page quantity surveyor for contractors.
- Project management and supervision on behalf of the client: to check quantities in payment applications and variations.
- Private homeowners: to get bids from several contractors for the same work.
If the terms are still confusing, there is a short explanation on the page what is a quantity surveyor. And if you need a quantity surveyor for construction projects for one stage only, you can hire one for that stage alone. The full list of services is on the page quantity surveying services.
A missing figure is marked as missing, not recorded as zero. An assumption is written as an assumption, with its source. That way everyone who receives the document knows what has been checked and what is still open, and the chance of discovering gaps only in the middle of construction is small.
What a professional quantity surveyor adds here. Part of the role is to ask. For example, the finishes specification mentions a washbasin with a vanity unit in all the bathrooms, and it is not clear whether that includes the guest toilet. A quantity surveyor who comes from the field, an engineer or a registered building technician who worked on site, like Yaakov Avital, records a question like this together with the assumption taken until it is answered, so that everyone who reads the bill knows what was assumed. More on a professional bill of quantities.
At each stage of the project the quantity takeoff serves a different purpose: an estimate at the start, a bill for the tender, and payment applications during construction. That is why the quantity takeoff should be kept in the same file throughout the project.
Frequently asked questions
Are chashav kamuyot and kamai the same role?
Yes. They are the two Hebrew names for a quantity surveyor, one profession, and the only difference is which name each person is used to.
Does a quantity surveyor work for the developer or for the contractor?
Both happen. On the client's side the quantity surveyor builds the bill and checks payment applications; on the contractor's side the quantity surveyor checks quantities for pricing and prepares payment applications. The work is similar, and the point of view is different.
When is the best time to start?
As early as possible. An estimate at the design stage allows corrections before the drawings are frozen. In any case, a bill of quantities before approaching contractors is the most important step.
Does the role of a quantity surveyor include setting the prices?
No. Real prices come from contractors' bids for the specific project. A cost estimate is an assessment based on stated assumptions, and it is a separate service from the bill of quantities.
Have a project? Tell me briefly what the project is and what already exists. When the project is a good fit, I usually reply with focused questions and a written quote.
Contact me for a quote* Created with AI for marketing, for illustration only. Not reviewed by Yaakov Avital and not professional advice. Every project must be checked on its own by a professional quantity surveyor and an engineer.