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Part of: What Is a Takeoff in Construction? How to Do One From Plans

Bill of Quantities vs Takeoff: How They Differ

A bill of quantities (BOQ) is a tender document that lists every item of work in a project with its measured quantity, so every bidder prices the same list. A takeoff is the measuring itself: the quantities you pull off the drawings, for your own scope, to build your own price. A bill of quantities is built from a takeoff, but it is written for all bidders and follows a published measurement standard. For the basics of measuring from plans, see how a construction takeoff works.

What is a bill of quantities?

A bill of quantities is a document used in construction tendering that itemizes the work so contractors can price it. Wikipedia's entry on the bill of quantities notes that quantities may be given by number, area, volume, weight or time, and that the bill needs a complete design and a specification before it can be prepared.

The point is fairness. Because every tenderer prices the same quantities, nobody wins or loses the job on how carefully they measured. Bidders compete on their rates instead.

Who prepares a bill of quantities?

A bill of quantities is usually prepared by a quantity surveyor or cost consultant working for the client, not by the contractor. The Designing Buildings wiki describes it as a document generally prepared by a cost consultant that gives measured quantities for the items in the drawings and specifications.

Quantity surveying grew up around the bill. Wikipedia's article calls the bill the original reason quantity surveying became a separate profession. In the US, cost estimators do much of this work for contractors, and when no bill is issued each bidder does a separate takeoff, or hires one out through construction takeoff services.

What is NRM2?

NRM2 is the RICS rulebook for measuring building work in a bill of quantities in the UK. Its full title is RICS New Rules of Measurement: Detailed Measurement for Building Works, and it sets detailed measurement rules for preparing bills of quantities to get a tender price. It also covers work that cannot be measured, contractor-designed work and risks.

According to Designing Buildings' NRM2 entry, NRM2 was published in April 2012, became operative on 1 January 2013 and formally replaced the old Standard Method of Measurement (SMM7) on 1 July 2013. The RICS NRM page lists the three volumes: NRM1 for cost estimating and cost planning, NRM2 for detailed measurement and NRM3 for maintenance work. The current suite was published in October 2021 and reissued in October 2022 with no material changes.

What does a bill of quantities contain?

A bill has more in it than measured work. Under NRM2, a bill is usually built from these parts:

• Preliminaries, priced on their own schedule. NRM2 includes templates for both a condensed and an expanded version.
• Measured work, item by item, with a description, a unit and a quantity for each line.
• Provisional sums, risks and credits, for work that cannot be fully defined at tender.
• Pricing summaries that roll the priced items up into a total.

A provisional sum is money set aside for work that cannot be defined in enough detail when the tender goes out. Designing Buildings adds that a bill is most useful when its work sections match the subcontract packages bidders are likely to let.

Why are bill quantities measured net?

Bill quantities are usually measured net as fixed in position, which means the quantity is what ends up built, with no waste added. The contractor allows for waste, laps and cutting in the rate instead.

You can see this written into real bid documents. The preamble to one published utility bill of quantities says its quantities were measured net as fixed in position, that the bidder must allow in their prices for waste and laps, and that the quantities are generally not suitable for ordering materials.

This is a big practical difference from a contractor's takeoff. Your own takeoff often ends with an order quantity that has waste added. If you take a net bill quantity, add your usual waste to it and also price waste into your rate, you have paid for the waste twice.

Bill of quantities vs takeoff: side by side

The two documents hold similar numbers but do different jobs. Here is how they compare.

Neither is an estimate. Both are lists of quantities, and the price comes from what you put against them. That split is covered in takeoff vs estimate.

How is a bill of quantities used after the tender?

A priced bill does not go in a drawer once the job is won. Designing Buildings notes that it helps agree the contract sum, gives rates for valuing variations, and forms the basis for interim payments and the final account.

That makes your rates matter long after the bid. A rate you set low to win the job can come back when a change gets valued at that same rate.

Should you check a bill of quantities with your own takeoff?

Yes, at least for the items that drive your price. A bill can contain errors, and an approximate bill is only an estimate of the final quantities. Measuring the big items yourself tells you whether the bill is close, and it gives you your own order quantities with waste added.

You can do that check straight from the tender PDFs. In MeasureFloorPlan you set the scale from one printed dimension per sheet, trace rooms for floor, wall and ceiling area, click runs for linear feet, count fixtures and export the quantities to Excel. Measure in the same units the bill uses so the lines compare directly. What each trade gets is listed under takeoff software for contractors, and other tools are compared in takeoff and estimating software.

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