Quantity surveying insights: a running blog, one short entry per publication
Quantity surveying insights, one for each publication: this is where the short points I wrote in posts and guides build up, newest first, each with a link to the full guide. I have extensive experience in quantity takeoff for construction, and this blog gathers what repeats itself from project to project.
How the quantity surveying insights are built
Each entry is written after a new post or guide: a title, a date, three to five lines, and at least one number that can be checked. The numbers are for illustration, and the full detail is in the guide linked at the end of each entry. There are no client or project names here, and missing data is marked as missing, not as zero.
October 2026
21/10/2026 · Two percent that nobody sees
A contingency allowance of about 2% (batzam, the Hebrew abbreviation for unforeseen items), contractor's all-risks insurance, bank guarantees, overheads and profit: all of them are multiplied, not added. In an example with a direct cost of one million shekels, a simple sum of the percentages gives 24.6%, and the chain gives about 27.7%. Every add-on needs a written basis. The guide: contingency, insurance and guarantees.
21/10/2026 · How many trucks leave an excavation
In the bill of quantities, excavation is measured by the volume before digging, but a truck loads loose volume. An excavation of 22 by 17 metres and 3.5 metres deep holds 1,309 m³ in place, and about 1,702 m³ loose after multiplying by 1.3. Whoever divides the first number by a load of 15 m³ gets about 88 trips instead of about 114, almost a quarter fewer than there will actually be. The guide: earthworks quantities.
21/10/2026 · A cubic metre of column versus a cubic metre of slab
The same concrete, a very different price: a column of 22 by 40 cm has 14.08 m² of formwork per m³, and a 20 cm slab only 5. In a sample calculation, a m³ of column came to about 2,192 shekels and a m³ of slab to about 1,245, at 2017 prices. The guide: concrete frame cost.
21/10/2026 · A cumulative account and the right index
In cumulative payment applications, under the accepted method, each period is linked to its own index value. Whoever links the whole cumulative amount to the latest index gets 14,100 in the example instead of 9,900. Before an argument, check what the contract says. The guide: index linkage and VAT.
21/10/2026 · A construction programme built from quantities
The duration of an activity equals the quantity, times the hours per unit, divided by the crew. 900 m² of slab formwork times 1.4 hours per m² is 1,260 hours; four formwork carpenters working nine hours a day finish in about 35 days, and a fifth carpenter brings it down to about 28. A programme like this can be checked and updated. The guide: construction programme.
21/10/2026 · From inputs to the price of a m² of plaster
A quarter of an hour of a plasterer, a quarter of an hour of a labourer and 0.02 m³ of ready-mixed plaster per m²: in the example the direct cost comes to 52 shekels, and the price with overheads and profit to about 60. An offer of 35 shekels per m² is below the direct cost, and it is worth asking how many hours were allowed. The guide: construction inputs.
19/10/2026 · Three quantities for the same work
Physical quantity, BOQ quantity and order quantity. For a wall of 14.00 m² with a window and a door, the bill records 14.00 m² under the deduction assumption of the example, 10.67 m² are actually painted on the wall, and the paint for two coats is ordered for 21.34 m². Each one is right for its own use. The guide: physical quantity, BOQ quantity and order quantity.
18/10/2026 · TAMA 38: a bill that starts with an existing building
A bill of quantities for TAMA 38 (Israel's national plan for strengthening existing buildings against earthquakes, usually with added floors) and for Pinui-Binui urban renewal (demolish and rebuild) is built on the same phases as a new building, but it starts with a building that is standing: a demolition and dismantling chapter, the strengthening of the structure and the tower of protected rooms (mamad, the reinforced safe room in every Israeli flat) as separate items, a separation between existing and new flats, and work in an occupied building as visible items. A quantity that depends on opening up is recorded as an assumption with a source. The guide: TAMA 38 bill of quantities.
15/10/2026 · A bill of quantities built from the model
When the model is orderly, the bill can run on it: every line leads back to the elements it was measured from, and a change in the model updates the quantity. The condition is model enrichment: consistent types, classification by chapter and data in every element. The guide: quantities from a model.
14/10/2026 · What to prepare before a quantity takeoff
Before you start, define what you need to receive at the end: a bill for a tender, quantities for construction or quantities for ordering material. Prepare five things: the type of project and the stage, the drawings or the model with their revision date, the chapters, the split into floors or flats, and the purpose. The guide: BOQ preparation.
| Date | Topic | The number to check |
|---|---|---|
| 21/10 | Percentage add-ons | 24.6% as a simple sum versus about 27.7% as a chain |
| 21/10 | Trucks from an excavation | About 88 trips versus about 114 |
| 21/10 | Column versus slab | 14.08 versus 5 m² of formwork per m³ |
| 21/10 | Cumulative account | 9,900 versus 14,100 |
| 21/10 | Construction programme | 35 days with four formwork carpenters, 28 with five |
| 21/10 | A m² of plaster | Direct cost 52, price about 60 |
| 19/10 | Three quantities | 14.00, 10.67 and 21.34 m² |
| 18/10 | TAMA 38 | Four chapters that change |
| 15/10 | A bill from the model | A line that leads back to the element |
| 14/10 | Before you start | Five things to prepare |
What every entry in the quantity surveying insights should answer
- What changed: one insight, not a summary of a whole guide.
- A number you can check: a quantity, a unit, and where it came from.
- Who it matters to: a developer, a contractor, a designer or a homeowner.
- Where to go next: a link to the full guide.
Please note: some of the examples in the blog were created with the help of artificial intelligence and are for illustration only. Every number is checked against the full guide, and every deliverable on a real project requires a professional check.
The entries in these quantity surveying insights come from a quantity surveyor's day-to-day work, so they are updated as projects accumulate.
Frequently asked questions
How often is a new entry added?
With every new post or guide. The entries are arranged by month, newest first.
Can I ask about a specific insight?
Yes. Leave a short enquiry on the site and mention the date of the entry.
Who writes the blog?
Yaakov Avital, a quantity surveyor for construction projects and a registered building technician, from day-to-day work on quantity takeoffs and bills 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.