Drawing change: variation, or design development?

Drawings evolve on every job. Some of that evolution is the design getting finished, and some of it is the design getting bigger. Only one of those is yours to absorb, and which one depends on the deal you signed.

The test: what did your price promise?

Where the client’s designer produces the drawings and you priced the set listed in the contract, your price covered those drawings at those revisions. When a later revision adds scope, quality or complexity, that is a change to what you priced: a variation, to be instructed and valued like any other. The check is the same ten minutes as in was it included: compare the priced revision with the new one, and name what moved.

Where your contract puts design on you, in whole or in part, the ground shifts. You priced an outcome: a building that works, complies and holds water. Detail that emerges to deliver that outcome is design development, and it is inside your price even though no drawing showed it on tender day. On design and build the battleground is the gap between the Employer’s Requirements and your Proposals, which has its own page.

The grey middle, honestly

Real jobs sit between the poles: you priced the client’s drawings but took on a design portion for one package. There the test runs package by package, and the answer for the roof can differ from the answer for the drainage. This is exactly where being organised beats being right: the party with the dated record of what each revision added usually wins the grey ones.

The habit that settles it

Answer every revision in writing, the week it lands. One email: revision received, what it adds against the priced revision, whether you treat it as development or as a change with a cost effect. Silence reads as acceptance, and a revision absorbed quietly in March is unarguable extra by November. This is practice, not law, and it is the whole game.

On a domestic job

Nothing here depends on the Construction Act. On a domestic extension the drawings are often the architect’s, the contract is thin, and the same rule applies with less paper around it: your quote covered the drawings it listed. When the architect issues a new one, the week-it-lands email is your price protection.

What to do this week

1. Make the priced revision list findable in one minute. It is the baseline every later argument is measured against.

2. Go through revisions received since pricing and send the catch-up email for any that added scope, honestly dated.

3. For the ones that are variations, price them now, through the ladder, into the next valuation.