Novation and Design-and-Build Contracts: What NW3 Homeowners Should Know

Introduction

In commercial construction, "design-and-build" procurement — where the contractor takes on both the design and the construction responsibilities — is common. In domestic projects, a related but distinct arrangement sometimes arises: the homeowner appoints an architect to carry the design to planning or technical design stage, then "novates" the architect's appointment to the contractor, making the architect contractually responsible to the contractor rather than the homeowner. For NW3 homeowners, understanding when and why this might happen — and its significant risks — is important. This guide explains novation and design-and-build in the domestic context. For related guidance, see our procurement options guide, JCT contracts guide and value of architect guide.

What Is Novation?

Novation is a legal process by which one party to a contract is replaced by a third party — with the consent of all parties. In construction, novation of the architect's appointment means:

• The architect, originally appointed by the homeowner (employer), is transferred to a new appointment with the contractor
• The architect then has a contractual duty to the contractor, not the homeowner
• The homeowner's direct contractual relationship with the architect ceases — the homeowner's design protections are now provided through the building contract with the contractor

Novation is commonly used in design-and-build procurement on commercial projects. In domestic projects, it can arise where a contractor requests to take over design responsibility, or where a project management structure involves the contractor "employing" the design team.

Why Novation Creates Risk for Homeowners

The fundamental risk of novation for a homeowner is the loss of an independent professional adviser:

• Once novated to the contractor, the architect's duty of care is owed to the contractor — not the homeowner. If a design decision benefits the contractor's construction efficiency at the expense of the homeowner's design aspiration or performance requirements, the novated architect may be in a conflict of interest.
• The architect can no longer act as contract administrator — because they cannot independently certify the quality and progress of work for which they are now contractually responsible to the contractor.
• Value engineering (reducing specification to reduce cost) is a common outcome of design-and-build — the novated architect may be pressured by the contractor to reduce specification to improve the contractor's margin.
• The homeowner has no independent professional to represent their interests during construction.

Design-and-Build in the Domestic Context

Design-and-build without formal novation — where the contractor takes responsibility for both design and construction under a single contract — is an alternative procurement route sometimes offered by builders in the NW3 market. Its attractions:

• Single point of responsibility — one contract for design and construction
• Potentially faster procurement — no separate design team appointment
• Contractor may have an existing relationship with a preferred architect or designer

Its significant disadvantages for domestic projects in NW3:

• The contractor-appointed designer works for the contractor, not the homeowner — the same conflict of interest as in novated appointments
• Design quality and planning appropriateness are not the contractor's primary interest — cost and speed are
• Without an independent architect, there is no professional managing the planning application, conservation area compliance, or design standard on the homeowner's behalf
• Contract terms in design-and-build favour the contractor — standard form JCT DB contracts place most risk on the employer

When Traditional Procurement Is Better

For the vast majority of domestic projects in NW3 — extensions, loft conversions, basements, refurbishments — traditional procurement (separate architect and contractor appointments; architect acts as contract administrator) is the better model. The homeowner has:

• An independent architect loyal to the homeowner throughout the project
• An architect who administers the building contract and certifies payments and practical completion
• Direct recourse to the architect under their professional indemnity insurance if design advice is negligent
• An architect who can push back on contractor claims and manage variations in the homeowner's interest

See our procurement options guide for a full comparison of procurement routes for NW3 domestic projects.

Conclusion

Novation and design-and-build arrangements create a fundamental conflict of interest that removes the homeowner's independent professional representation. For complex, high-value or conservation area projects in NW3, this is a significant risk. Traditional procurement — with an architect appointed directly by the homeowner throughout the full project — provides the best protection for design quality, cost management, and construction oversight. Use our free matching service to find an architect who works exclusively for the homeowner, on traditional procurement terms. For cost guidance, visit hampsteadrenovationcosts.co.uk.