Quantity surveying: the field, the methods and the tools
Quantity surveying is the field that turns drawings, specifications and models into quantities that can be priced, compared and controlled. Behind every number in a bill of quantities (BOQ) there are decisions of method: what is measured, in what unit, from which source and from which version of the design. Whoever knows these decisions reads a bill of quantities differently, and knows which questions to ask before the numbers go out to contractors.
The principles quantity surveying is built on
The work rests on a few simple principles. They sound obvious, but most arguments about quantities start exactly where one of them was not kept.
- Every quantity has an explicit unit. m², m³, m (linear metres), tonnes or units. An item without a clear unit is an item that every contractor will price differently.
- The method of measurement is agreed on each project. Whether openings are deducted, what the item price includes, and how repeated details are measured. The definition is written in the item description or in the chapter notes, so that all the bidders price the same work.
- Every quantity has a source and a date. A drawing, a sheet or a model, and which revision. When a new design version arrives, the items that changed are marked, together with how much they changed.
- Missing data is marked as missing. Not as zero and not as a silent estimate. A visible gap can be filled, whereas a wrong zero passes every check and only shows up on site.
- An assumption is written as an assumption. When there is no detail or specification, the assumption is recorded next to the item, and the client knows exactly what to approve or correct.
Another principle is the distinction between three quantities for the same work: the physical quantity from the design, the quantity in the bill according to the method of measurement, and the quantity ordered from the supplier. The full explanation, with a numerical example of a single wall, is in the guide physical quantity, BOQ quantity and order quantity.
Chapters and phases: the skeleton of every bill of quantities
A building's bill of quantities is divided into chapters following the standard numbering of the General Specification for building works (Israel's inter-ministerial specification). The numbering gives an orderly structure that every contractor knows. The method of measurement usually rests on the methods of measurement in the General Specification, and on each project it is worth checking what the particular technical specification changes. Above the chapters there is a division into phases, which is convenient both for checking and for payment.
| Phase | Example chapters |
|---|---|
| Structural frame | 01 Earthworks, 02 Cast-in-situ concrete, 03 Precast concrete, 13 Prestressed concrete, 19 Structural steelwork, 23 Piles |
| Masonry and envelope | 04 Masonry, 05 Waterproofing, 06 Joinery and steel metalwork, 12 Aluminium, 22 Prefabricated building components |
| Finishes | 07 Sanitary installations (in the building BOQ usually only the sanitary ware), 09 Plaster, 10 Flooring and wall cladding, 11 Painting, 14 Stonework, 40 External works |
| Consultants | Inclusion of the consultants' BOQs as received, without any change to their content: electrical, HVAC, plumbing, fire protection and lifts |
In an existing building and under TAMA 38 (Israel's national plan for strengthening existing buildings against earthquakes, usually with added floors), demolition and dismantling chapters are added, as well as protection chapters for the protected rooms (mamad, the reinforced safe room in every Israeli flat). When the work is split between subcontractors, each chapter becomes a closed package with its own preliminaries, scope boundaries and a split between supply and installation, and the shared site costs are shown separately.
How models changed the work
Until a few years ago most measuring was done from drawings, line by line. Today many projects come with a Revit model, and quantities can be produced from it by element, floor and building. Measuring takes less time, but judgement remains.
A model is built for design and coordination, not for a bill of quantities. So it is checked before it is relied on: which elements are missing, how walls and floors were defined, and whether identical buildings were linked twice. On large projects repetition is handled in two separate layers, identical buildings and typical floors within a building, and each layer is shown on its own so that it can be checked. You can read about working from a model on the page quantities from Revit and BIM models.
When there is no model, the takeoff is done from DWG or PDF files. That is entirely possible, and it is stated in the document, so that everyone who reads the bill knows what the basis was.
Quality control: how you know the quantities are right
A correct quantity is one that has been checked from several directions. These are the checks I usually run before delivery, depending on the type of project and the material:
- Totals that must reconcile. The areas by use add up to the total area; above ground and below ground together equal the total; repeated floors plus the floors measured separately equal the whole building.
- Double counting. An element that appears in two chapters, or that was measured both in the model and on a drawing, is caught here.
- Units and descriptions. Every item is read again together with its unit, so that no item is left in m² that was measured in linear metres.
- Comparison with the drawing. An unusual number is checked against the drawing itself, by eye, and not only against the formula that calculated it.
- Versions. When a new revision arrives, it is compared and the changes are marked, instead of everything being quietly recalculated.
Missing data is not zero. In a good bill of quantities you can see explicitly what has not been designed yet, what was assumed and what was measured. That way whoever prices it knows what they are pricing, and the client knows what remains to be completed.
The tools and experience behind the work
The daily work is done in Revit, AutoCAD, Autodesk Takeoff and Excel: models and drawings for measuring, and spreadsheets for the bill of quantities and the checks. In pricing and in work with contractors, Israeli software such as Dekel, Ramdor and Binarit is also common. The tool matters less than the method, because the same method has to hold both when the model is incomplete and when there is only a PDF file.
I have worked in the field since 2012: concrete and rebar takeoffs on a large shopping-centre project in Tel Aviv, design and pricing of urban infrastructure, pricing and quantity surveying at a company that built additions in hospitals that stayed in operation and at a main contractor, and independent work since 2024. What you can actually order is set out on the page quantity surveying services.
What a professional quantity surveyor adds here. Quantity surveying is also a critical reading of the documents. For example, the number of flats in the permit drawings differs from the number in the construction drawings, or the specification lists layers in the protected-room walls that are not marked on the drawings. A quantity surveyor who comes from the field, an engineer or a registered building technician who worked on site, like Yaakov Avital, records every such gap in the comments and questions sheet, and the designers decide. More on a professional bill of quantities.
Frequently asked questions
What is the difference between quantity surveying and quantity takeoff?
Quantity takeoff is the measuring itself. Quantity surveying also covers what surrounds it: the structure of the bill, the item descriptions, the method of measurement, the cost estimate and the control. There is a separate page on the measuring itself, step by step: quantity takeoff for construction projects.
Is every bill of quantities measured by the same method?
No. The chapter numbering is standard and shared, but the method of measurement is agreed on each project and written into the item descriptions and notes. So two bills for the same building can show different quantities, and both are correct by their own method.
Can quantities be produced without a model?
Yes. When there is no model, the work is done from DWG or PDF files, and this is stated in the document. The work is more manual, so it matters to receive the latest drawings and the area schedule right at the start.
Who needs a service like this?
Developers, contractors, design offices and private homeowners, at any stage where you need to know how much work there is and how much it will cost. If it is not clear what suits your project, start with a short conversation with a quantity surveyor who will go through the material. What the role actually includes is also explained on the page what is a quantity surveyor.
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.