The point: a BOQ is a list of quantities someone else measured. It contains mistakes, and the unpriced-items rule means mistakes become your cost. Checking it takes an hour and regularly finds thousands.
Check 1 — Units. Read down the unit column. Is there a length item among areas, or an area item that should be a count? Remember the measurement convention: items over 300 mm wide (a wide tread, a wide upstand) are normally measured in m², and narrower ones in metres. A unit change at 300 mm is correct, not an error.
Check 2 — Splits and totals. Where a quantity is split by location or block, add the split up. It must equal the total.
Check 3 — Quantities that don't make sense. Compare related items:
- Finished floor area against screed area — they should be close.
- Wall waterproofing against wet-area perimeter × required height.
- Skirting length against room perimeters.
- Roof fillets against roof perimeters, not roof area.
Real example. A housing tender measured wall waterproofing in showers as the perimeter × 0.30 m. Every unit had showers and built-in baths, where walls normally need waterproofing to full shower height. The take-off formula hid a large gap in plain sight.
Real example. Another tender measured the length of a roof fillet almost exactly equal to the roof area. A fillet runs around the edges, so its length should relate to the perimeter. One of the two numbers was wrong.
Check 4 — Descriptions under headings. In a BOQ, a heading describes the items below it. Never attach a description that sits under an item to the item above it. Misreading the heading structure is a common way to price the wrong system.
Check 5 — Unpriced items and the deemed-included rule. Most conditions say any item you leave unpriced is deemed included elsewhere. That means it's free. Price every line, including accessories: mats, nosings, trims, sealants.
Real example. A floor-coverings submission left 21 entrance mats unpriced. Under the tender's rules those mats would have been supplied free.
Check 6 — Hidden allowances. Look for notes such as "quantities include 5% waste" or "allow for all labours". Waste included in quantities changes how you apply your own waste factor.