This article relates to Australian architectural, building, interiors, landscape projects of any size or type, be it housing, multi-residential, industrial, commercial.
Builders use designer drafted plans and documents (ie the building contract) to price projects then build them. These documents theoretically describe all the work so it happens accurately according to the design.
Plans and drawings show layouts, arrangements, primary components, structures, dimensions and things best shown graphically. Schedules are quick reference tools, lists of materials, colours, finishes.
Specifications are written booklets describing technical detail that is too extensive to put on drawings or in schedules. This detail is the repetitive construction detail that applies to the materials and components described in on the drawings and in schedules.
Why specify this detail when contractors know and do it anyway?
A few contractors and subcontractors do not work as well as they should. Also, those that do (the majority) may do some in a way that does not suit the design. The specification has the detail so work can be done properly and suitable to the design.
Why can’t the designer just have a single sheet of drawing notes in lieu of a specification?
Some designers do contract documents without a full specification, relying on a drawing sheet of notes. While these notes are better than no specification, they don’t cover all things and contingencies.
A vital function of a specification is to give all detail to accurately price and build the project. They also tie together the limited detail in the drawings and on schedules.
Specifications are vital in other ways. While they provide a lot of important detail, they also provide the ability to resolve random construction problems. A specification is like an insurance policy.
The specification gives peace of mind, including for the builder when it is in subcontract agreements, and provide a sense of certainty by accounting for virtually all things.
Building work is simply too complex, resource-consuming, and expensive to not use a full construction specification. A designer who forgoes a full specification puts themselves and their clients at great risk.