Structural frame price per m²: how contractors on site price it, and how to calculate the m²
Anyone looking for a structural frame price per m² soon finds that frame contractors do not speak the language of the bill of quantities (BOQ). The methods of measurement measure a column in m³ by its cross-section, a beam by its type and a slab in m²; the contractor on site prices a built m², a cubic metre of concrete or a dwelling unit. Both languages are correct, and the quantity surveyor's job is to translate between them without losing quantities on the way.
How contractors on site really price
From my years with a main contractor, working with subcontractors, the picture repeats itself in most projects. A structural frame contractor gives a price per built m² of the floors, sometimes with a separate price for the basement and the roof. They do not ask whether the concrete goes into a beam or a slab; for them it is the same working day of a crew, a pump and formwork. A concrete contractor who prices only the pour talks in m³, again with no distinction between beam and slab. Finishing contractors price per dwelling unit: plaster per flat, flooring per flat, paint per flat, and sometimes per m² of the flat's floor area rather than per m² of wall.
The General Specification for building works (Israel's inter-ministerial specification) measures differently. In its concrete works chapter, concrete is measured net, complete in place, by volume in m³, separately for each type and strength of concrete. Columns are measured in m³ with their cross-section stated, and their height runs from the top face of the slab to the underside of the beam or slab above. Slabs are measured by area in m² to their external dimensions, and beams contained within the slab thickness are measured as part of the slab. Ring beams are measured in linear metres, and blinding concrete by area. This is precise measurement, but it is not the language in which the contractor gives the price.
Why this gap matters for the budget
When the BOQ speaks the language of the methods of measurement and the contractor prices per built m², someone has to convert. If the conversion is done by eye, two things usually drop out: work that is not a "typical floor" (a raft, a double slab, thickenings, transfer beams, a roof with parapets) and areas the contractor counts at half (balconies, roofs). In tenders I priced for a main contractor, the difference between a quote calculated on raw m² and one calculated on weighted m² was sometimes the difference between profit and loss on the project. The types of quantity are explained on the measured, BOQ and order quantities page.
Structural frame price per m²: how to calculate the m² the contractor actually prices
The way I work is to calculate, for each slab, the walls beneath it, and to give each area a weight according to the amount of work it demands from the frame contractor. The weights below are an example of the method I usually use; in each project they are set again from the drawings and in agreement with the contractor.
| Area | Weight | Why |
|---|---|---|
| Building area of a typical floor | Full weight | A full floor: slab, walls, columns and beams |
| Sun balcony | 75% | Slab and parapet, without full walls |
| Cantilevered balconies and roofs | 50% | The frame contractor has little work in them beyond the slab |
| Addition for tall floors | 30% | An unusual floor height adds formwork and scaffolding |
| Double slab, thickening, transfer slab | 30% | Another slab, foundation or thickening beyond a typical floor |
| Raft | 70% | In addition to the floor area; in some projects it is counted in full |
| Walls above roofs, about a third of a floor high | 50% | Up to half a floor high; the parapet is included in the roof |
The quantities themselves sit underneath these numbers. Floor and roof slabs are thickness times area. Walls are section times net height, that is, the gross floor height minus the slab thickness; otherwise the slab is counted twice. Beams over openings are calculated from the net height minus the opening height. The parapet concrete is counted in the m³ of the walls even when the parapet itself has zero weight. This way the weighted m² and the m³ converge on the same figure, and you can check one against the other. More on that check on the quantity cross-check page.
Example: a building with balconies and a roof
For illustration, take a building of four typical floors, each with 500 m² of building area and 80 m² of cantilevered balconies, a 500 m² roof and a 520 m² raft. The raw m² of the slabs, balconies and roof, without the raft, is 2,820 m². The weighted m² by the table is 4 × 500 at full weight, plus 4 × 80 at 50%, plus 500 at 50%, plus 520 at 70%: a total of 2,774 weighted m². In this example the difference is small, because the balconies and the roof are offset by the raft. In a building with a large roof, a double basement and a retail floor of unusual height, the difference may be much larger, in either direction. The point is not the number but the method: a structural frame price per m² without saying which m² cannot be compared.
Why a price list is not enough. A general price list gives a price per m³ of concrete by the methods of measurement, but the contractor who submits a quote prices a weighted m² in their head. If you want to compare quotes, you need both: a BOQ by the methods of measurement, and next to it a calculation of the weighted m². The gap between a price list and market price is covered on the construction price list vs market price page.
What a professional quantity surveyor adds here
Measuring only what is marked on the drawings gives the right m³ of concrete for each element, and misses what the contractor sees. A quantity surveyor who comes from the field, an engineer or a registered building technician who worked on site, like Yaakov Avital, prepares both pictures: the bill by the methods of measurement, and the weighted table by floor, with a reason for each floor being at full weight or at half. For example, the drawings show a double-height ground floor with a transfer slab. In the bill that is a few dozen more m³. In the weighted table it is an addition for height and for thickening, and without it the contractor's quote may be too low, with the difference coming back later as a request for extra payment. The gap is recorded as a question to the designer and the contractor, and they decide.
Even when the contractor gives a structural frame price per m², a quantity takeoff by the methods of measurement helps you check whether the price is reasonable. Whoever holds the quantity takeoff can translate the price per m² back into m³ of concrete and tonnes of steel.
Frequently asked questions
Why does a frame contractor not price by the BOQ?
Because they estimate work, not elements. The crew, formwork, pump and crane days depend on the floor's area and height, so the built m² is their natural unit. They use the BOQ for checking and for interim payment applications, not for the first pricing.
How do I compare a quote per m² with a quote per m³?
Calculate the same basis for both: the project's weighted m² and the total m³ by the bill. Once the basis is shared, the comparison is on price alone. How this is done for a tender is explained on the quantity surveyor for contractors page.
Are the weights in the table fixed?
No. They are an example of a working method, and they change with the project, the contractor and the construction method. What is fixed is the principle: every area has a weight with a stated reason, and every number in the table is a formula you can trace.
Is this relevant to a private house too?
Yes, on a small scale. A private house also has a roof, balconies and a ground-bearing slab, and the contractor prices per m². The work of a quantity surveyor for construction projects starts there with the same question: which m².
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.