Insurance and Warranties for London Renovation Projects: What You Need and When

Insurance during a renovation is one of the most overlooked aspects of project planning. Standard home buildings and contents insurance typically excludes or significantly limits cover during construction works. A fire, flood, theft, or structural collapse during a renovation — events that are statistically more likely during works than at any other time — can leave a homeowner with no cover and very significant uninsured losses.

This guide sets out the insurance framework for a London renovation project: what the contractor must hold, what the client must arrange, and what warranties to obtain at completion.

The contractor's insurance obligations

A reputable contractor will hold — and must be able to evidence — the following:

Public liability insurance (minimum £2m, typically £5m for London projects): Covers the contractor's legal liability for injury or property damage caused to third parties (neighbours, passers-by, the client) by the contractor's operations. This is the most important policy to verify. Demand the certificate before work starts — not an assurance that it exists.

Employers' liability insurance (minimum £5m, mandatory by law): Covers the contractor's liability to directly employed workers who are injured or become ill as a result of work. Legally required for any employer. Applies to directly employed workers; the status of subcontractors varies and should be confirmed.

Contractors' all-risks (CAR) insurance: Covers the works themselves — materials on site, work in progress — against physical damage (fire, flood, theft, vandalism). This is distinct from public liability and covers the asset being built, not third-party liability. Confirm that the contractor's CAR policy covers the full reinstatement value of the works, and that the excess is reasonable.

Professional indemnity (where relevant): If the contractor is providing design services (design-and-build contract), they should hold professional indemnity insurance for the design element.

The client's insurance obligations

Notify your insurer before work begins: Most standard home insurance policies require the policyholder to notify the insurer before undertaking significant works. Failure to notify may invalidate the policy for unrelated claims during the works period, not just claims related to the renovation. Call your insurer before work starts.

Check the policy exclusions during works: Standard buildings insurance policies typically exclude or limit cover for: - Structures undergoing demolition or renovation - Structural collapse resulting from works - Theft of materials or equipment on site - Damage caused by the contractor's operations (this is the contractor's responsibility, but if the contractor's insurance is inadequate or disputes the claim, the client may face a gap)

Contract works insurance: If the contractor's CAR insurance does not cover the full value of the works, or if the contractor is not insured to the level required, the client should arrange contract works insurance. This covers the works in progress against physical damage from the client's side.

Unoccupied property insurance: If the property is vacated during works (common for whole-house renovations), standard home insurance often lapses or is significantly restricted after 30–60 days of unoccupancy. Specialist unoccupied property insurance is required. This is more expensive than standard cover and may impose conditions (regular inspections, security standards).

Latent defects insurance (Structural warranty): For new-build work (a new basement, extension, or loft conversion), a structural warranty provides protection against latent structural defects for 10 years from completion. The warranty is provided by insurers (NHBC, LABC Warranty, Build-Zone, Premier Guarantee) and typically requires an approved inspector to inspect and certify the works at defined stages. A structural warranty is typically required by mortgage lenders where the works constitute a material addition.

At completion: what to obtain

Building control completion certificate: Issued by the local authority building control (LABC) or an approved inspector (such as NHBC or LABC) when the works are completed to building regulations standard. Essential — without this, the works are not formally certified as compliant. Required by mortgage lenders and disclosed at sale.

Part P electrical certificate: Issued by the electrical contractor (NICEIC or NAPIT registered) certifying that the electrical installation complies with BS 7671. Required for any new electrical circuits.

Gas Safe certificate: Issued by the Gas Safe registered engineer for any new or modified gas installation.

FENSA certificate: For replacement windows and doors installed by a FENSA-registered contractor, certifying compliance with Building Regulations Part L and Part N.

Structural engineer's completion report: For works involving structural design (removing load-bearing walls, installing beams, basement construction), the structural engineer should issue a completion report confirming that the structure was built in accordance with the design.

Party wall surveyor's completion notice: Where a Party Wall Award was in place, the appointed surveyor should confirm that the works are complete and that the schedule of condition prepared before works began can be used to assess any damage claims.

Warranties for installed products: Boiler manufacturer's warranty (typically 5–10 years with annual service), window and door warranties, kitchen appliance warranties, specialist product warranties (stone sealants, specialist coatings, waterproofing membranes). Collect all warranty documents at handover and file them.

A practical checklist

Before work starts: - [ ] Contractor's public liability certificate obtained and checked (dates, insured name, level of cover) - [ ] Contractor's employers' liability certificate obtained - [ ] Client's home insurer notified of works - [ ] Unoccupied property cover arranged if property will be vacated - [ ] Contract works cover confirmed (contractor's CAR or client's policy)

At completion: - [ ] Building control completion certificate - [ ] Part P certificate (if electrical works) - [ ] Gas Safe certificate (if gas works) - [ ] Structural engineer's completion report (if structural works) - [ ] Structural warranty (if new-build element) - [ ] All product warranties and operating manuals

ASAAN provides a handover pack at the completion of every project containing all certification, warranties, and operating documents. If you are managing your own project, ensure your main contractor contractually obliges delivery of these documents before final payment is released.