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Fitness for Purpose: Why Builders Need to Watch Their Design Liability

One of the most overlooked risks in D&C contracts is the fitness for purpose obligation.

This obligation is often buried in a few short lines of contract text, but its consequences can be enormous. Unlike the typical “due care and skill” standard owed by consultants, fitness for purpose is an absolute obligation: the works must achieve a specific result or performance outcome, regardless of how carefully they were designed or built.

The danger?

If the design underperforms or fails — even when it has been prepared, signed off, and certified by an independent consultant — the liability can land on you as the builder. Under many D&C contracts, the builder doesn’t just construct to the drawings; they inherit the full design risk, effectively guaranteeing that the design will work as intended.

This often arises where:

  • The contract imposes a fitness obligation on the entire works
  • Consultants are novated mid-project, breaking design continuity
  • The builder doesn’t verify if designs meet performance specs

What you can do:

  1. Remove or limit fitness obligations and replace with “due care and skill” where possible
  2. Ensure consultant contracts include equivalent obligations so liability doesn’t solely rest with the builder
  3. Review your PI insurance as many policies exclude fitness for purpose liability
  4. Clarify the intended use of the project in writing

Fitness for purpose clauses can transform a construction risk into a professional liability risk—and most builders aren’t insured for that. For builders in the D&C space, this is not a clause to gloss over, and the safest and most cost-effective time to manage the risk is before the contract is signed. Once you’re locked in, you’re potentially committing to a performance guarantee you can’t fully control.

Treat it as a red flag, and deal with it early, clearly and in writing before you sign.