Build a partida from its precio descompuesto

Put the mano de obra, materiales and maquinaria into the catalog as priced resources, each with the unit it is bought or paid in and a resource type that says which of the three it is. An hour of oficial de primera, a tonne of cement, a day of retroexcavadora.

Why: Every partida in the presupuesto will lean on these same few dozen rates. Priced once, a change to the steel price moves every partida that contains steel in one edit. Priced inside each partida, the same change is a search through four hundred lines and you will miss some.

Anything made on site before it goes into the work is an auxiliar: the mortero, the hormigon amasado en obra, the encofrado you assemble and reuse. Build each one as its own assembly, in its own unit, from the resources you just priced.

Why: The mortero appears in the brickwork, the rendering and the paving, and it is one mix. Modelled once as an auxiliar it stays one number in three partidas. Retyped into each of them it is three numbers that drift apart the first time the sand price moves, and nobody notices which one is stale.

Build the partida as an assembly in the unit the bill measures it in, and give every component the quantity of that resource one unit of work consumes. Add the costes indirectos and the medios auxiliares as their own components so a reader can see them rather than infer them from a coefficient.

Why: The rendimiento is the number the argument is actually about. Written down, a client who thinks one point three hours per square metre is generous can say so and you can answer with a postcalc. Buried in a lump rate, the same disagreement comes out as a claim that you are expensive, and there is nothing to point at.

Apply the assembly to the position in the bill so the unit rate is the total of the descomposicion rather than a number somebody keyed in. Do the same for the partidas that share a recipe and differ only in thickness or diameter.

Why: A typed rate and its breakdown stop agreeing the moment either changes, and the bill is the one everybody reads. Linking them means the presupuesto you print and the calculation you defend are the same arithmetic, which is the whole reason for building the descomposicion in the first place.

Move the descompuestos you are happy with into the cost database as your own base de precios, with the codes you want to search by. The next presupuesto starts from these instead of from a published base you have to correct in the same three places every time.

Why: A published base de precios is a good starting point and a poor finishing one: its rendimientos are regional averages and its prices are last year's. The version corrected by your own jobs is worth more than either, and it only accumulates if somebody puts it somewhere other than in the last project folder.