Insurance for Home Renovations in London: What You Need, What Your Contractor Should Hold and What to Check

The obligation: most home insurance policies require you to notify your insurer before any significant building work begins. Failure to notify can invalidate the policy. This applies even if the work is being done by a professional contractor and not by you personally.

What "significant building work" means varies by insurer, but typically includes:

• Any structural extension or alteration
• Roof works
• Works involving electrical or plumbing alterations
• Substantial internal refurbishment
• Any work that means the property is unoccupied or at materially increased risk during the works

Likely insurer responses: when you notify, your insurer may:

• Extend your existing policy to cover the works at no additional premium (less common for major works)
• Impose additional conditions or excesses for claims arising during the construction period
• Decline to extend cover, requiring you to arrange separate renovation insurance
• Increase the premium to reflect the additional risk

If your insurer declines to extend cover or imposes conditions you consider unreasonable, you may need to arrange a specialist renovation insurance policy to run alongside or in place of your standard home insurance for the duration of the works.

A specialist home renovation or site insurance policy provides cover for:

Contract works cover (all-risks): covers the building works themselves — materials on site, partially completed work, and the structure under construction — against damage from fire, flood, storm, theft, vandalism, or accidental damage. Without this, if a partially completed extension is damaged by fire or a storm, the cost of rebuilding the damaged works falls on whoever is at risk — typically the homeowner or, if under a JCT contract, the party specified in the contract as responsible for this insurance.

Employer's liability: if you engage any workers (including direct labour — individuals you employ directly on a cash or casual basis, not through a main contractor), you have employer's liability obligations. Employer's liability insurance is a legal requirement wherever an employer-employee or deemed-employer relationship exists. Penalty for non-compliance: up to £2,500 per day.

Public liability: protects against third-party claims (neighbours, passers-by, visitors) for injury or property damage caused during the renovation works.

Legal expenses: some policies include legal expenses cover for disputes arising from the works.

Policies are available from specialist renovation insurers and brokers (e.g., Buildstore, recognised trade body Insurance, self-build insurance specialists). Cover is typically arranged for the duration of the contract, with premiums based on the contract value.

Even where a professional contractor is engaged, the contractor's insurance obligations do not substitute for the homeowner's — they complement them. Verify the following before work starts:

Public liability insurance: the contractor must hold public liability insurance (minimum £2 million, and preferably £5 million or £10 million for larger projects) covering third-party injury and property damage claims arising from their activities on site. This is the most basic insurance requirement.

Employer's liability insurance: if the contractor employs any workers (including subcontractors who are not themselves self-employed for insurance purposes), they must hold employer's liability cover for a minimum of £5 million (a statutory minimum under the Employers' Liability (Compulsory Insurance) Act 1969).

Professional indemnity (PI) insurance: if your contractor has a design function (design-and-build, or has produced drawings, specifications, or design input), they should hold PI insurance covering claims arising from design errors or omissions. Minimum cover level: typically £500,000 to £2 million depending on project scale.

How to verify: do not simply accept a contractor's word. Request certificates of insurance for all relevant policies before starting work, and check:

• That the policy is current (not expired)
• That the named insured matches the contracting entity
• That the cover level is adequate for the scale of the project
• That the activities described in the policy cover the type of work being carried out

For reputable contractors on a recognised trade body, recognised quality scheme or independent client reviews accredited schemes, insurance verification is part of the registration process. However, renewal dates change — always ask for up-to-date certificates, not just accreditation confirmation.

What is a structural warranty?: a structural warranty (also called a latent defects insurance policy) provides cover for major structural defects that emerge after construction is complete — defects that are not immediately visible but become apparent over time (e.g., foundation settlement, structural cracking, water ingress through defective waterproofing). The cover period is typically 10 years from completion.

Who needs one?: structural warranties are typically required by mortgage lenders for new build homes and significant structural conversions or extensions. If you are building an extension or conversion that will be mortgaged, or if you intend to sell the property within the first 10 years after completion, a structural warranty may be required by the buyer's lender.

How they are obtained: structural warranty providers (NHBC Buildmark is the most common, but others include Build-Zone, Premier Guarantee, and LABC Warranty) require the project to be registered with the warranty provider at the start of construction, with inspections at key stages. The cost is typically 0.5 to 1.5% of the construction cost. The warranty cannot be retrospectively applied after completion.

Alternative to structural warranty: for smaller projects and homeowners not intending to sell, some solicitors accept a Professional Consultants Certificate (signed by an architect or engineer who has inspected the works) in lieu of a structural warranty — but this is entirely at the discretion of the buyer's lender, and is becoming increasingly uncommon.

The Party Wall etc. Act 1996 does not require specific insurance, but it is closely linked to the general liability position. If your contractor damages a neighbour's property during works (for example, causing structural movement or cracking), the contractor's public liability insurance should cover the claim — provided the contractor carries adequate cover and the damage is within the scope of the policy. Ensure your contractor's PLI limit is sufficient for the potential exposure on a party wall project in London, where neighbouring properties may be of significant value.