How to Read a Bill of Quantities (And Why It Matters)

A bill of quantities (BOQ) is a document that itemises the work in a construction project by description and measured quantity. Contractors price the BOQ at tender, and the priced document becomes a contract schedule used for progress claims, variation pricing, and final account reconciliation.

Most contractors have priced BOQs. Fewer have read them carefully enough to understand what they're signing up for.

The structure of a BOQ

A standard BOQ is structured by trade or building element, with each section containing:

• Item description: what work is being measured
• Unit: the measurement unit (m², m, nr, item)
• Quantity: the measured amount
• Rate: the contractor's price per unit
• Amount: quantity × rate

The total of all amounts gives the contract sum — before preliminaries, contingencies, and margin are added.

Measured vs. provisional quantities

This is the most important distinction in any BOQ.

Measured quantities are quantities that have been calculated from the drawings. The contractor prices these rates and is paid for the actual quantity of work done. If the design shows 500m² of slab and the contractor pours 520m², they are paid for 520m².

Provisional quantities are estimates for items where the quantity isn't known at tender stage — often substructure items like excavation, rock breaking, or piling. The contractor prices a rate, but the quantity is confirmed during construction.

Provisional quantities shift quantity risk to the client. If the actual quantity significantly exceeds the provisional, the cost increases. Builders who don't identify provisional items before they price sometimes find their margin compressed by an item they thought was measured.

The risk in "item" rates

Some BOQ items are priced as a lump sum against the description "item" rather than a measured quantity. These are typically site-specific costs — site establishment, site sheds, temporary services — that don't lend themselves to measurement.

The risk with "item" rates is that the scope of the item isn't always clearly defined. A site establishment item might or might not include temporary perimeter fencing. If that's not specified, a variation claim is likely.

Where scope gaps hide

The BOQ and the specification work together. The BOQ measures the quantity; the specification defines the quality. A BOQ item for "ceramic floor tiles" without a specification reference could mean anything from a $15/m² tile to a $150/m² tile.

Before pricing a BOQ, check:

• Are all BOQ items cross-referenced to the specification?
• Are there items in the specification that aren't measured in the BOQ?
• Are there items on the drawings that appear in neither?

Those gaps are where variation claims are born.

Using the BOQ in administration

Once the project is running, the priced BOQ is the pricing schedule for all claims. Variations are priced using the BOQ rates where applicable. Progress claims are verified against the BOQ items.

A BOQ that was priced carelessly at tender creates problems at administration. Items priced at zero to win the contract create tension when those items are needed for variation pricing. Rates that don't reflect actual costs create cash flow pressure from the first claim.

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We prepare BOQs and provide independent tender review as a standalone service. Contact us to discuss your tender requirements.