Quantity Surveying
Accurate quantity calculation based on field measurements. El-Eman Office provides quantity surveying to save costs.
Steps in taking off quantities, from measurement to schedule
Survey-based quantity take-off begins by defining the scope of work and the measurement units for each item, such as cubic metres for excavation and square metres for floors. Field measurement is then carried out with the instruments, the results are converted into a model or sections, and quantities are extracted from them. What was measured on site is compared with what is on the drawings to show the differences. It is important that all parties agree on one calculation method before starting, since the difference between the cross-section method and the digital terrain model method can show up in the final volume, and the reference must be agreed in the contract.
Sources of disagreement and how to settle them
- Over-excavation: any excess beyond the designed dimensions, caused by sloping or collapsing sides, is paid or not paid according to the contract terms.
- Bulking and compaction factors: soil increases in volume when excavated and shrinks when compacted, and the contract should state how this is handled.
- Material waste: calculated as a reasonable agreed percentage, not left to estimation.
- Hidden works: such as foundations and waterproofing, need measuring and recording before they are covered.
The best way to settle disputes is a joint measurement attended by the owner's and the contractor's representatives before works are backfilled or covered, with the figures signed in a record.
Quantities as a monitoring tool, not just for pricing
A project benefits from take-off in tracking progress: the monthly work done is compared with the plan, and from it comes the real percentage of completion on which payment certificates are based. Periodic take-off also exposes waste of materials or surplus work early. On large projects, take-off linked to the schedule allows material needs to be predicted and deliveries to be scheduled. The better the measurements are documented with photographs and coordinates, the easier they are to refer back to in a review or arbitration.
- Agree the measurement system and the take-off items before work begins.
- Measure hidden works and record them before they are covered.
- Combine field take-off and drawings in one table showing the differences.
- Update the take-off with every design change or variation order.
Take-off at different project stages
Take-off is used differently at each stage. Before contracting it supports the estimate and the bill of quantities on which tenders are based. During construction it is used to measure monthly progress. At handover, the final as-built quantities are taken off and compared with the contract to settle the final account. To avoid disputes, both parties should agree who does the measuring, when, and how the figures are signed. If variation orders arise, their quantities should be taken off separately and approved before they are carried out.
Frequently asked questions
What is the difference between take-off from drawings and survey take-off?
The first reflects the theoretical design, while the second reflects what was actually built or the current state of the land, and they often differ.
Is take-off needed on a small project?
It helps whenever earthworks or concrete works are large or a dispute is possible; for small works a simple take-off is enough.
When is measurement done before construction?
Before excavation starts and before any material is removed, because the original ground is the basis of the calculation.
