If you run a construction firm in Essex, Kent, or London, chances are you have signed: or been asked to sign: a Design and Build (D&B) contract. Over the past decade, D&B has become the default procurement method for everything from commercial refurbishments to residential developments. It is easy to see why clients love it: they get a single point of responsibility. One team handles the architectural vision, engineering, and physical construction from the ground up.
However, speaking with contractors on sites across the South East, I often notice a dangerous misconception. Many general contractors assume that if they hire an external architect or a specialist engineering sub-consultant to handle the design work, any design liability stays squarely with them. In reality, under standard contract law, you: the main contractor: remain entirely responsible to the client for the entirety of the package, including every stroke of the pen drawn by your subcontractors.
When things go wrong, the client does not chase the independent structural engineer down a rabbit hole; they sue you. And if your insurance setup isn't properly aligned, you could be left footing a six-figure bill out of your own pocket. Let's examine what a D&B contract actually means for your liability, how recent legal shifts have raised the stakes, and what your Construction Contractor Insurance must cover to keep your business safe.
The Single Point of Responsibility Trap
Under a traditional procurement route, the employer contracts separately with the designer and the builder. If a beam fails because of a design defect, the employer sues the designer. If it fails because of poor workmanship, they sue the builder.
D&B completely upends this division. By signing a D&B contract, you assume joint liability for both design errors (traditionally a Professional Indemnity concern) and physical defects (traditionally covered by General Contractor Liability Insurance or Contractors' All Risks policies).
As Teresa Yardley, Head of Professional Indemnity at NBS Underwriting, pointed out in a recent industry insight, modern construction underwriting has had to evolve rapidly to meet this reality. NBS Underwriting’s design-and-construct policy wording, for instance, specifically spans the entire project life cycle: covering mechanical and electrical contractors as well as full D&B firms up to £100m turnover. But policies vary wildly across the market, and assuming your standard public liability policy covers design errors is a gamble that rarely pays off.
The Shadow of the Building Safety Act and URS v BDW
If you think design liability only matters for major commercial towers in the City of London, think again. The regulatory landscape changed dramatically with the introduction of the Building Safety Act 2022 (BSA) and landmark case law such as URS Corporation Ltd v BDW Trading Ltd [2023] EWCA Civ 772.
In URS v BDW, the Court of Appeal confirmed that developers and contractors can face massive claims for structural design defects long after practical completion, with limitation periods extending up to 30 years retrospectively for certain dwellings under the Defective Premises Act 1972, and 15 years prospectively.
For contractors working on residential conversions, apartment blocks, or mixed-use schemes across Kent and Essex, this creates a terrifying "long-tail" exposure. A design error made today on a ventilation or compartmentation detail might not surface until a decade from now: and under current legal precedents, your business could still be held liable.
This is why Professional Indemnity (PI) cover is not an optional extra; it is the backbone of your business defense. Because PI is written on a "claims-made" basis: meaning the policy must be active when the claim is made, not just when the work was done: maintaining continuous cover and understanding run-off provisions is vital, even if you decide to wind down or retire.
How the Market is Responding: PI Extensions and Wordings
Insurance markets have started reacting to these mounting pressures. Specialty underwriting agencies and syndicates: such as Euna and NBS: have introduced robust policy extensions to help bridge the gap between traditional liability and modern D&B demands. When evaluating your Business Insurance in Essex or Business Insurance in London, you need to look closely at whether your policy includes critical extensions such as:
- Civil Liability Wording: Ensuring coverage responds to broader breaches of professional duty and statutory obligations, rather than a narrow "negligence-only" trigger.
- Mitigation and Rectification Costs: Covering reasonable expenses incurred to fix a design flaw before it turns into a catastrophic physical failure or formal legal claim.
- Collateral Warranties and Step-in Rights: Ensuring your PI policy fully covers your obligations under warranties given to property purchasers, tenants, and institutional funders.
- Adjudication and Defense Costs: Confirming that legal and expert fees are covered in addition to the policy limit, rather than eating directly into your indemnity limit.
Practical Steps Every Contractor Must Take
As a business owner juggling tight margins, labor shortages, and complex supply chains, insurance might feel like just another administrative burden. But taking a proactive approach to your contract and insurance review can save your company from insolvency. Here are four practical steps to take before your next project kicks off:
1. Review Contracts Before Signing
Never sign a D&B contract without legal and insurance scrutiny. Watch out for onerous "fitness-for-purpose" clauses. Standard insurance policies typically cover you against professional negligence (failing to exercise reasonable skill and care). If a contract guarantees that your design is fit for a specific purpose, you may have entered into a strict contractual warranty that standard PI policies exclude.
2. Audit Your Subcontractors' Professional Indemnity
If you delegate design work to specialist M&E engineers, architects, or cladding designers, verify their PI insurance. Do they carry adequate limits? Are their retroactive dates properly aligned with the project start date? Do not rely on verbal assurances; request copies of their insurance certificates annually.
3. Secure Comprehensive Design & Construct PI
Standard public liability insurance will not protect you against a flawed architectural layout or an incorrect structural calculation. You need a dedicated Construction Contractor Insurance package that integrates both public/employers' liability and robust Professional Indemnity cover. If you are operating across competitive regional markets, working with a specialist business insurance broker can help you access leading UK underwriting markets that understand your specific trade.
4. Maintain Run-Off Cover
If your company changes its structure, merges, or directors retire, do not simply cancel your PI policy. Because of the 15-to-30-year limitation periods under the Building Safety Act, historic liabilities do not disappear when you close the doors. Securing appropriate run-off cover ensures past projects remain protected.
Protecting Your Business Future in Essex, Kent, and London
The construction industry in the South East remains as dynamic as it is challenging. Design and Build procurement offers fantastic opportunities for growth, but it concentrates risk squarely on your shoulders. You cannot afford to treat your insurance policy as a tick-box exercise.
At Moyak Insurance Services, we take an individual approach and care deeply about every client we serve. As a trusted business insurance broker operating across Essex, Kent, and London, we deal directly with the UK’s leading master insurance brokers and underwriting agencies. We help local contractors secure comprehensive, tailored cover that matches their exact project scope: often saving businesses a fortune on their small business insurance quotes without leaving dangerous gaps in protection.
Don't wait for a dispute over a design defect or a building safety notice to test your policy. Get in touch with our expert team today to review your D&B contracts and ensure your construction contractor insurance is truly built to last.