An extension, loft conversion or major refurbishment can improve a rental property. It can also make the building more expensive to reconstruct after an insured event.

The purchase price or current market value does not answer this insurance question. Buildings cover is normally based on the cost of reinstating the property, and a figure that was reasonable before substantial work may no longer be sufficient afterwards.

What does rebuilding cost include?

Rebuilding cost is the estimated amount required to reconstruct the insured building following a total loss. It is not simply the price of bricks, timber and labour. Depending on the property and policy, the calculation may need to reflect:

• Demolition and removal of debris
• Construction materials and labour
• Architects’, surveyors’ and engineers’ fees
• Planning, building-control and other statutory costs
• Access restrictions and specialist equipment
• The reinstatement of outbuildings, walls, drives and other insured structures
• Compliance with applicable building regulations

Market value is influenced by location, demand, rental prospects and land value. Rebuilding cost is concerned with putting the physical property back. Either figure may be higher, so one should not be substituted for the other.

Which improvements could change the figure?

Any work that changes the size, layout, construction or specification of a building should prompt a review. Examples include:

• Adding a rear or side extension
• Converting a loft, basement or garage into accommodation
• Creating additional bedrooms or bathrooms
• Converting a house into flats or an HMO
• Installing higher-specification kitchens, bathrooms or finishes
• Adding solar panels, heat pumps or other fixed equipment
• Constructing garages, offices or substantial outbuildings
• Altering the roof, structure or external walls

Even where the market value increase appears modest, the cost of recreating the altered property may change significantly. A small extension can involve drainage, foundations, steelwork, roofing and professional fees.

Should landlords wait until renewal?

No general rule says that a landlord can safely wait. The policy may require notification of material changes during the insurance period, and building work itself can present risks that ordinary landlord insurance was not designed to cover.

Contact the broker or insurer before work starts. Explain the scope, cost, duration, contractor arrangements, occupancy and security. Structural alterations, hot works, scaffolding, an exposed roof or an empty building may affect the terms, excesses or availability of cover.

Once the work is complete, confirm the finished layout, use and rebuilding figure. Planning approval or building-control completion does not automatically update an insurance schedule.

Does index-linking solve the problem?

Some policies index-link the buildings sum insured to changes in rebuilding costs. This may help a figure keep pace with general construction inflation, but it cannot know that a landlord has added a bedroom, converted a garage or installed specialist materials.

Index-linking adjusts an existing starting figure. It does not correct an inaccurate assessment or automatically account for physical changes. Landlords should check both the original figure and subsequent improvements rather than assume the annual adjustment has dealt with everything.

What could underinsurance mean for a claim?

The effect depends on the policy wording and circumstances. Some policies may apply an average or proportionate settlement where the declared value is below the correct rebuilding cost. Others may contain different limits or conditions.

For example, if a building is insured for materially less than its true rebuilding cost, the insurer may argue that the premium and cover were based on an incomplete value. This can affect a partial claim as well as a total loss. The insurer decides how the wording applies, but the practical lesson is clear: the figure should be reasonable, supportable and kept under review.

An invoice for improvement work is useful but is not necessarily a rebuilding assessment. The project cost may exclude demolition, debris removal, inflation, fees or the cost of reconstructing the original building.

How should a landlord review the rebuilding value?

For a straightforward property, an appropriate rebuilding-cost calculator may provide general guidance when accurate measurements and property details are used. Non-standard, listed, mixed-use, heavily altered or complex buildings may require an assessment from a suitably qualified surveyor.

Keep plans, specifications, approvals, completion documents, invoices and photographs. Tell the person completing the assessment about every extension, conversion and insured external structure.

Portfolio landlords should review each address individually. Applying the same percentage increase across every property can miss differences in construction, access, location and previous improvements. Although insurance principles are broadly similar throughout the UK, construction requirements, professional costs and statutory processes can differ, so the assessment should reflect the property’s actual location.

Why NetRent starts with the property, not the premium

NetRent has worked with landlords for more than 23 years. We speak personally with every client to understand the property, work completed, intended use and wider portfolio before introducing them to Clear Insurance Management. That conversation can identify extensions, conversions or other changes that may not be obvious from an old schedule.

NetRent is the insurance introducer, not the broker. Clear provides regulated insurance broking services, considers the available options and arranges cover where appropriate. NetRent remains available throughout because we seek long-term working relationships with landlords rather than one-off introductions.

Through the scale of the landlord business we introduce and our relationship with Clear, we aim to help landlords obtain appropriate, cost-effective cover instead of focusing only on the cheapest headline premium.

If your rental property has been extended, converted or substantially improved, do not assume the existing figure has kept up. Send NetRent your current schedule and details of the work before renewal—or sooner where the policy requires notification.

Call 01352 721300 or email insurance@netrent.co.uk.

NetRent does not provide legal advice. This article represents our general understanding of the landlord insurance and rental property market and is provided for information only.