How do you check site numeracy claims in Qardho?

Site numeracy competency risks in Qardho come down to evidence. A team that can measure, convert units and read a drawing will show you setting-out sheets, mix ratio cards and bar bending schedules. A team that cannot will describe the work in words. Before work starts, ask for those records and re-measure one grid line or one bar length with your own tape.

Where does the gap between a claim and the drawing start?

The gap opens at the first setting-out task. Numbers move from a drawing to the ground through a tape, a level and a person. If that person reads a dimension of 4.20 m as 4.02 m, or adds a 100 mm wall thickness where the drawing measures to the structural line, the error travels through every later trade.

Unit conversion and ratio work cause the same class of problem. A mix written as 1:2:4 is a volume ratio, and a crew that treats it as a weight ratio changes the cement content without changing the look of the wet mix. Bar lengths and lap lengths are the third check: a bar bending schedule that does not match the drawing produces steel that cannot be fixed as detailed.

Ask the person who set out the work to sign the setting-out sheet with the date. That sheet, checked against the drawing, is the evidence. Ask the project engineer for the setting-out sheets and inspection records, and walk a recent build with your own tape to compare one measured bay against its drawing.

How do you check the numbers before work starts?

Checking means independent measurement, not a conversation. Pick three items from the drawing and measure them yourself: one grid line, one bar length on site, and one mix batch. Write the measured value next to the drawn value and keep the paper.

Confirm the general practices the team claims to follow. Lap lengths, cover to reinforcement and bar bending dimensions should be taken from the project's specification or engineer, not from what a crew learned elsewhere. Volume batching of concrete is general practice on sites without a batching plant, and the batch boxes used should match the ratio on the drawing.

A short walk over a recent site shows how numbers are written down, whether dimension strings are marked on the ground, and whether the same tape is used for setting out and for checking. Look at the corners: a square corner measured across both diagonals tells you whether the setting-out crew understands rectangular geometry, not just tape reading.

What does the gap do to the finished work?

Measurement and quantity errors appear late. A short bar length is found when the steel will not reach the cover line. A wrong mix ratio shows in cube results or in surface wear. A setting-out error of one wall thickness shows when partitions, doors and floor tiling will not fit the room sizes on the drawing.

Correction then costs more than the original check. Concrete set in the wrong place must be broken out or redesigned around. Steel cut short must be replaced or lapped, and laps changed on site need the engineer's approval, checked against the project specification.

Reduced levels are the quiet version of the same risk. Ask for the level book with the benchmark and the closing check. Where no level book exists, ask the supervisor how levels were transferred and compare that answer with the site's own marks.

What to do next

Before releasing the next payment stage, request the setting-out sheet, bar bending schedule and batch records for the work completed, then re-measure one grid line and one bar length yourself. Check what your contract allows you to require as evidence, and put the tolerance and record requirement in writing with the next instruction. Where the records do not match the drawing, ask the project engineer to confirm the correction before the following trade starts.