Insurer requirements and mortgage conditions vary, so obtain a written response for your actual project rather than relying on a general rule for every policy or lender. [1] [2]
Give the insurer a clear description
Aviva's guidance, updated on 20 July 2026, identifies extensions, loft conversions and structural alterations as changes to discuss with the insurer. The proposed work can affect the insurer's assessment and the cover available during construction. [1]
Prepare a short description with the drawings, intended start and finish, contractor details and whether you will remain at home. Ask what further information the insurer needs about security, exposed areas, temporary protection and periods when the property will be unoccupied.
Request confirmation of the cover that remains in force, any exclusions, conditions, additional premium and who needs to arrange any separate protection. Keep the response with your policy documents, not only in a conversation with the contractor.
Check your particular mortgage conditions
Do not assume that all mortgage contracts require identical notifications. For example, Nationwide's published conditions applicable to England require necessary consents, compliance with relevant requirements and restrictions on alterations that reduce value; they also address changes of use and insurance. That example does not determine another lender's requirements. [2]
Send your lender the proposal where its conditions require notification or approval, and ask it to confirm anything unclear. Distinguish an enquiry about permission for alterations from an application to borrow more: approval of one should not be assumed to answer the other.
Ask what insurance is needed during the works
Your home policy and the contractor's arrangements need checking against the project rather than against the statement “the builder is insured”. Ask the insurer or broker who covers the existing building, the new work, stored materials and the risks created by the temporary construction state. Aviva recommends discussing the works and the contractor's insurance before starting. [1]
Use the written answers to identify gaps. Do not buy overlapping policies or rely on a certificate without understanding the insured work, period, exclusions and parties covered.
Leasehold flats need a building-level check
For a flat, the freeholder may arrange the buildings policy and cover can differ from your personal contents arrangements. LEASE advises checking the terms and responsibilities rather than assuming everything inside and around the flat has the same cover. [3]
Ask the managing agent who must notify the building's insurer and request evidence that the planned alterations have been considered. Keep any landlord consent separate from the insurance confirmation.
Update the record when the project changes or finishes
Tell the insurer when the agreed description or occupancy arrangements change and ask what it needs at completion. Check the appropriate rebuilding cover, which is not the same question as the likely sale price; mortgage conditions can require insurance for rebuilding costs. [1] [2]
Retain the confirmations, relevant completion documents and final description of the work. Where requirements conflict or cover is unclear, resolve that uncertainty with the lender or insurer before authorising the affected work.