Specification

A specification is the written record of exactly what is being supplied. It states the product codes, dimensions, materials, finishes and performance standards the goods or works must meet, in enough detail that two different people ordering from it would order the same thing. It is the document a dispute is settled against, which is why it is written before anything is bought rather than assembled afterwards out of an email thread.

Three documents get confused with each other on the same job. A scope of works says what will be done. A specification says what it will be done with, and to what standard. A bill of quantities says how much of each item there is, priced line by line. A well-run project carries all three and they have to agree with each other.

What a specification states

The content changes by trade but the function does not. In promotional merchandise a specification carries the supplier product code, the PMS color reference, the decoration method, the imprint position and size, and the artwork version being used. In office furniture it carries the manufacturer code per item, the fabric grade and finish code, and the handing of anything asymmetric. In electrical and lighting work it carries cable sizes, containment types, luminaire product codes and the standard the installation will be certified against.

What makes a specification useful is that every line can be checked on delivery. A finish described as "dark grey" cannot be checked; a finish given as the manufacturer's code can. Anything left to interpretation is a cost that lands later, usually as a restocking charge on a made-to-order item the supplier is under no obligation to take back.

"Or equal and approved" and substitutions

UK construction and lighting specifications often name a product and add "or equal and approved". That does not mean any similar product is acceptable. It means an alternative may be offered and the specifier has to approve it in writing before it is bought. The approval is the operative half of the phrase, and the common failure is ordering the alternative on the strength of the first two words.

Substitution is also where value engineering happens legitimately, when a cheaper equivalent meets the same standard. The test is the same either way: the specification is reissued with a new version number and date, and the person who owns it signs the change off before any order is placed.

In Zigaflow a specification can be held on the quote line it belongs to, so the version that was priced is the version that reaches the supplier order. See how quoting works.