Medir el plano a una partida codificada del presupuesto

Open the sheet, set the scale against a dimension printed on the drawing, and measure the areas, lengths and counts you need. The measurements stay on the sheet where they were taken.

Por que: A measurement you can point at on the drawing is checkable by somebody else in a minute. The same number in a spreadsheet cell is only as good as the memory of whoever put it there, and on a revision it has to be redone from scratch because nobody can see what it covered.

Group the measurements into the quantities the bill will actually carry, in the units the measurement rules give for each kind of work, and check the totals against anything you already know about the building.

Por que: The unit is part of the measurement rule, not a formatting choice, and a quantity carried in the wrong one produces a rate that is wrong by a factor rather than by a margin. It is also the last cheap moment to notice that a floor is missing from the take-off.

Put the quantity on a bill item under the right section and give the item its code. The national schedule gives nine digits; a project bill extends that with a three-digit sequence of its own, so a code of either length is what the bill ends up carrying.

Por que: The code is the item's identity for the rest of the job. It is what lets a settlement bill be compared against a tender bill after both have been renumbered, and it is what lets two bidders' prices for the same work be set against each other at all.

Beside the code, write out what the item actually covers: grade, mix, thickness, finish, method, and anything about access or sequence that changes the price. It is free text, so it can say whatever the item needs it to say.

Por que: The characteristics are what the code cannot carry, and they differ for every kind of work: what you must state for concrete is nothing like what you must state for windows. An item described in three words gets priced three different ways by three bidders, and the difference becomes yours to absorb at settlement.

Run validation on the bill. For a project in China the GB 50500 rules are selected for you: they find items carrying no code at all, and codes that are not a well-formed nine or twelve digits. If your bill form also has a code column of its own, make sure the code being checked is the one on the item rather than a second copy typed elsewhere.

Por que: This checks the shape of the code, not whether that code exists in the national schedule, so a well-formed number nobody ever published passes. Read a clean run as having cleared the typing errors, and read the codes yourself for the ones that matter.