What is a quantity surveyor and what do they do on a construction project
What is a quantity surveyor? A quantity surveyor is an engineer or a registered building technician, like Yaakov Avital, who turns the drawings of a construction project into quantities: how many m³ of concrete are in a slab, how many m² of flooring are in a flat, how many metres of railing run along the balconies. Pricing, the tender, the contract with the contractor and the payments throughout construction all rest on these quantities.
What is a quantity surveyor, and where the Hebrew name comes from
In Hebrew a quantity surveyor is called a kamai, from the word kamut, quantity. On site two names are used for the same profession, kamai and chashav kamuyot, and the work is identical. The whole field is called quantity surveying (kamaut in Hebrew), and it deals with a question that comes back on every project: how much work and how much material the design contains, and how to present them so that they can be priced and compared.
A quantity surveyor does not design the building and does not build it. The job is to read what the designers drew on the drawings or built in the model, measure quantities from them, and organise those quantities in a structure that every contractor can price on the same basis. When all the bidders price the same list, the bids can finally be compared.
What a quantity surveyor actually does
- Quantity takeoff from PDF or DWG drawings, or from a Revit model when there is one. Every quantity is recorded with its source and with the date of the version it was measured from.
- Bill of quantities (BOQ): the document in which the quantities are arranged by chapters and items, with a description and a unit of measurement for each item. Contractors put their prices on it. There is a detailed explanation in the guide to the bill of quantities.
- Cost estimate: an assessment of the project's cost based on the quantities and the assumptions, before there are real bids from contractors.
- Bid comparison: when all the contractors have priced the same bill, you compare the bids line by line and see where the gaps are.
- Support during construction: checking the quantities in the contractor's payment applications and in variations, meaning work that did not appear in the original bill.
Not every project needs the whole list. A private house usually needs one bill of quantities, which several contractors price. On a large project the quantity surveyor supports several stages. The full picture, stage by stage, is on the page what a quantity surveyor does at each stage.
How a quantity surveyor differs from a land surveyor, a valuer and a site supervisor
The simplest way to answer ‘what is a quantity surveyor’ is to compare the role with the professionals who work alongside it. The names sound alike, so people mix them up, but each of them delivers something different in the end.
| Professional | What they do | What you get from them |
|---|---|---|
| Land surveyor | Measures the site and the structure as it stands, on site and with instruments | A survey map, levels and positions |
| Real estate valuer | Assesses the value of a property, of land or of rights | A valuation opinion |
| Site supervisor | Follows construction on site on behalf of the client: quality, compliance with the drawings and progress | Supervision reports and comments to the contractor |
| Designer: architect, engineer or consultant | Designs the building and its systems | Drawings, specifications and models |
| Quantity surveyor | Turns the design into quantities and into a structure that can be priced | Quantity takeoff, bill of quantities and cost estimate |
There are overlaps between them. A quantity surveyor has to understand design in order to read it, and has to understand construction in order to spot what is missing from the drawings. But a quantity surveyor does not replace a site supervisor, and does not survey the site with instruments.
Who can be a quantity surveyor, and what matters in their experience
A good quantity surveyor is usually a civil engineer or a registered building technician. Site experience matters just as much: someone who has seen how a slab is poured, how windows are installed and what a contractor's payment application looks like can usually spot gaps in a drawing and write clearer items, which narrow disputes over interpretation.
In my own work I bring both sides. I am a building (civil) technician with a diploma, listed in Israel's official register of technicians, and a certified works manager. Since 2012 I have worked in quantity surveying and pricing: concrete and rebar takeoffs on a large shopping-centre project in Tel Aviv, design and pricing of urban infrastructure, building additions in hospitals that stayed in operation, and a role as estimator and quantity surveyor with a main contractor. Since 2024 I have worked independently as a quantity surveyor for construction projects, and I handle each project personally.
When to bring a quantity surveyor into the project
- At the design stage, when you want to know whether the budget fits what is being designed, before the drawings are frozen.
- Before a tender or before approaching contractors, so that all the bids price exactly the same work.
- For a private house, once there are permit drawings and before you ask contractors for quotes.
- For a contractor, before submitting a tender bid, to check the quantities that came with the tender documents.
It helps to know what you need the quantities for: a tender, a budget, comparing bids or ordering material. The answer sets the structure of the work and the level of detail. If you are still deciding whom to choose, there is a guide to choosing a quantity surveyor with a ready list of questions.
What a professional quantity surveyor adds here. A professional quantity surveyor reads the documents together, not each one on its own. For example, a consultant's report defines work in all the rooms, and the architectural drawing marks it in only some of them. Measuring by the marking will miss the rest. A quantity surveyor who comes from the field, an engineer or a registered building technician who worked on site, like Yaakov Avital, flags the gap as a question, and the designers decide. More on a professional bill of quantities.
Frequently asked questions
Are kamai and chashav kamuyot the same thing?
Yes. They are two Hebrew names for the same profession, and in English both mean a quantity surveyor. Some people are used to kamai and some prefer chashav kamuyot, and the work itself is identical.
What is a quantity surveyor's job on a private house, and do you need one at all?
On a private house the quantity surveyor usually prepares a bill of quantities that several contractors price. That way you compare price against price for the same work, instead of comparing lump-sum quotes that each include something different.
Does a quantity surveyor supervise the work on site?
No. Supervision is a separate role. A quantity surveyor can check quantities in payment applications and in variations, but is not responsible for the work on site. Responsibility for construction and for supervision is set in the project's contracts and building permit.
How much does a quantity surveyor cost?
It depends on the size of the project, on the material that already exists and on what the work includes. The page how much a quantity surveyor costs has sample prices and a calculator for illustration.
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.