In brief
- A bill of quantities lists each item of work with its quantity, unit and rate, so work can be measured and paid for line by line.
- Without one, progress payments and changes are hard to measure and agree, so prepare it from the drawings or agree another way to measure and pay.
- Check that quantity times rate gives the amount, that no item appears twice, and that a contingency line is present.
Contents
A bill of quantities, usually shortened to BOQ, is a list of every item of work on a project with its quantity, unit and rate. Each line says what the work is, how much of it there is, and what one unit is paid. It turns drawings into something you can measure, price and pay against. The construction risk analyzer counts a BOQ among the documents a project should have, and gives the reason: without one, progress payments and changes are hard to measure and agree. Its remedy is to prepare a bill of quantities from the drawings, or agree another way to measure and pay for work. Its limitation is that some lump-sum contracts do without one.
What goes on each line of a BOQ?
Each line carries a category, an item description, a quantity, a unit, a rate and an amount, and a line needs an item plus either an amount or both a quantity and a rate. Where no amount is given, the amount is quantity times rate, and all amounts sit in one currency. The construction budget analyzer reads a cost breakdown as CSV, one line per item under a header row, and it accepts category, or section, or trade for the grouping column; item, or description, for the text; quantity, or qty; unit; rate, or unit rate; amount, or total, or cost; and optionally the month a line is spent and whether it is imported. Quantities come from the drawings. The construction material calculator works out blocks, plaster, reinforcing steel, floor tiles, paint and roofing sheets from dimensions, and the concrete calculator works out concrete for slabs, beams, columns and footings. Confirm units against the project's specification before pricing anything.
How do you check a BOQ before you rely on it?
Run the arithmetic and the shape of the list, then have a quantity surveyor review it. The analyzer checks the lines on several points. It flags a line where quantity times rate differs from the amount by more than one percent, because one of the three is wrong. It flags the same category and description on two lines, which may mean they are counted twice. It flags a zero or negative amount, usually a missing rate or a credit entered as a cost. It flags one line carrying over a quarter of the total, since a single large line hides quantities that are hard to check, so that line should be broken down. With eight lines or more, it flags lines lying more than three interquartile ranges above the upper quartile. It also flags a budget where most of the total sits in lump sums, the lines with no quantity and rate that cannot be measured line by line. In the analyzer's own sample budget, whose amounts are made up to show the checks, a blockwork line of 100 m2 at a rate of 10, amount 1000, entered twice, is flagged as the same item appearing more than once, and a plaster and paint line of 50 m2 at a rate of 10 with an amount of 600 is flagged because 50 times 10 does not give 600.
What headings does a BOQ usually follow?
The order is a prompt to check, not a standard, and a building budget commonly runs through: preliminaries and site set-up; substructure and foundations; frame and structure; walls; roof; doors and windows; finishes; electrical services; plumbing and drainage; external works; professional fees; contingency. A road budget has its own list: preliminaries and site set-up; earthworks; sub-base and base; surfacing; drainage and culverts; road furniture and markings; professional fees; contingency. The analyzer flags a budget with no contingency line, and one whose contingency is under five percent of the total; that five percent line is the tool's rule of thumb and not a standard, so agree the figure with the engineer on the job. The analyzer checks a budget's arithmetic and shape only. It does not judge whether quantities or prices are right, it applies no benchmark, so it never says a rate or a total is high or low, it is not a cost estimate or professional advice, and a quantity surveyor should review any budget a reader relies on. Figures entered are not stored. You can load a CSV into the construction budget analyzer and work out before you commit which lines fail the arithmetic, which items appear twice, whether most of the money sits in lump sums, and whether a contingency line exists at all.
What to do next
Take the priced BOQ you intend to sign or pay against and export it as CSV with one line per item. Paste the rows into the budget analyzer and run the checks. Fix the lines it flags, correcting the quantity, the rate or the amount, splitting any line that carries over a quarter of the total, and adding the missing contingency. Then send the corrected list to a quantity surveyor for review before the first payment is certified.
Frequently asked questions
Does every contract need a bill of quantities?
No. Some lump-sum contracts do without one, but the construction risk analyzer still counts a BOQ among the documents a project should have, because without it progress payments and changes are hard to measure and agree. Where there is no BOQ, agree another written way to measure and pay for work.
Does the budget analyzer tell me if my prices are high?
No. It checks a budget's arithmetic and shape only, and applies no benchmark, so it never says a rate or a total is high or low. It is not a cost estimate or professional advice, and a quantity surveyor should review any budget you rely on.
Where do the quantities on a BOQ come from?
From the drawings. The construction material calculator works out blocks, plaster, reinforcing steel, floor tiles, paint and roofing sheets from dimensions, and the concrete calculator works out concrete for slabs, beams, columns and footings. Check the units against the project's specification before pricing.