Insuring your home extension

Extending your home can expand your space and add value to your property. Find out how to make sure your home has the right cover when you’re building an extension.

Kim Jones
Kim Jones
Updated 08 August 2023  | 3 mins read
Reviewed by Jasmine Hembury

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Increase your space

With the right cover in place

Extending your home can expand your space and add value to your property. Find out how to make sure your home has the right cover when you’re building an extension.

What insurance do I need for building an extension?

Adding an extension to your home is a big project which can end up costing a lot more than you budgeted for if things don’t go to plan.

Collapsing walls, electrical fires and water leaks can be more likely during construction work. As well as your home and its contents being exposed to the elements when walls are knocked down.

If you don’t let your insurer know you’re building an extension, it could invalidate your home insurance policy, leaving you uninsured while work is happening.

Once you’ve told your provider, you may find that your home is still insured as normal and nothing changes with your policy. Some insurers don’t require you to have additional cover if a home improvement project is small or costs less than a certain amount.

But others will withdraw cover or impose restrictions, leaving you either completely or partially uninsured.

For example, you may not be covered for damage to the existing building, or theft from your home, while the building work is underway.

If that’s the case, you’ll need to buy home renovation and extension insurance from your current insurer as an add-on to your policy.

If your provider doesn’t offer this cover, you can buy it from another provider to ensure your home remains fully insured throughout the build.

Key points

  • You need to tell your insurer before you start any major home renovations
  • Most standard home insurance policies won’t cover building work as standard because claims are more likely
  • Separate specialist insurance can provide cover to protect your home during renovations
  • Your home insurance premium might go up if your extension makes your rebuild costs higher

What to consider when you’re building a home extension

Whether you’re extending upwards, outwards or even down into the basement, structural work needs careful planning.

To begin with, you’ll have to produce detailed plans and make sure you’ve got planning permission (if required). And you’ll need to choose your contractors carefully.

Your home insurer is unlikely to cover any work that your contractor carries out that is below standard or dangerous.

You’ll also need to ensure the extension complies with building regulations. These ensure that the structural integrity of the extension, its energy and insulation performance, as well as its electric and gas safety meet a minimum set of standards.

Once you’ve got plans drawn up by an architect or builder, you’ll need to get them approved by your local council’s building control department before work starts on the project.

Then it’s a case of making sure you’ve budgeted for everything. All of the project costs - including the design and construction, fittings, furnishings and decoration. Plus, alternative accommodation costs if the build is so disruptive you have to move out and spend time in a hotel.

It’s also important to make sure your home’s insured while the work’s being done and that you have the right level of cover once the renovation is finished.

How does building an extension affect my home insurance?

Building an extension increases the level of risk to your home, which makes it more likely you’ll need to make a claim.

For this reason, standard home insurance providers are less likely to provide cover during building work or they’ll charge you extra.

There are two main types of risk associated with renovation projects:

Structural risks

Knocking down walls can cause unexpected accidents or damage. Structural work can expose your home to the elements for long periods of time, which could also damage your property.

Security risks

During building work your home can be less secure. For example, you might need to temporarily move out, scaffolding can make access easier for intruders, tradespeople may be coming and going all day, and there’s potential for windows and doors to be left open.

Remember that having an extension is likely to increase how much it would cost to rebuild your home from scratch – which can increase the amount of home insurance cover you need.

Do I need to tell my insurance provider about my extension?

Yes, you’ll need to make your insurer aware of the work you’re doing.

If your insurance provider doesn't know about your building work and your plans for adding an extension, it can invalidate your policy.

By contacting your insurer, you can check if your home will be covered and to what level. You may need additional or specialist cover for it to be fully protected.

In fact, whatever type of major building work you’re doing, you should contact your insurer. They don’t need to know about cosmetic changes you make to your home - like painting and decorating. But you should let them know about larger projects like:

  • Knocking down load-bearing walls
  • Extending a room
  • Adding a conservatory
  • Converting a loft
  • Re-roofing

When do I need to contact my insurance provider?

You need to contact your insurer before the building work starts to check whether it could invalidate your policy.

Let your insurer know when you’re in the planning stage and be very clear about the work you’ll be having done. If plans change along the way, make sure you keep them informed.

Your provider will be able to explain the type of insurance you’ll need and whether you’ll be covered for the building work or if you’ll need specialist insurance during this period.

Your provider can also help update your home insurance once the extension’s finished - making sure you’ve got the right level of cover and that it reflects the new rebuild value of your home.

Does my builder cover the work?

Even if the builder has insurance, your building work and home may not be fully protected - so it’s important to take out your own cover.

Check your builder has valid insurance before they start work and ask for proof of:

Public liability insurance - Covers costs if the builder or their work causes someone to get hurt, or if someone’s property gets damaged as a result of your building work.

Employers’ liability insurance - To cover you and the builder if someone were to get hurt while they were working on your building project.

I have materials on site - are these covered?

Building materials are unlikely to be covered by your home insurance.

You’ll usually need to have separate cover for theft of contents and any building materials or equipment left on site.

Speak to your insurer first, to see if they can cover this. If they can’t, you can typically buy this cover as part of specialist renovation insurance.

What does extension and home renovation insurance cover?

If you’re having major work done - for example, something structural that’s more than just fitting a new bathroom or kitchen – you may need specific home renovation insurance. Policies differ but many typically include cover for:

  • Damage to the existing structure of the property - So your building remains fully insured while building work is going on.
  • Public liability insurance - Pays for damages if someone is injured in an accident or their property is destroyed during building work. If a roof tile falls off and hits someone, or their car, for example.
  • Your personal possessions - Contents are covered if they’re damaged or lost due to things like theft, fire or flood.
  • Malicious damage - Pays out if your building or contents are damaged by vandalism.
  • Theft of building materials and tools on site - Some thieves target homes under construction as they know there could be a lot of expensive equipment lying around.
  • Cover for damage caused by a fire, earthquake or explosion.
  • Alternative accommodation - Pays for hotel or other accommodation expenses if your home becomes uninhabitable because of work on the extension.
  • Protection when your building is unoccupied - Your home is covered if you can’t stay there for more than 30 days because of the building work.
  • Legal expenses - If there’s a dispute that needs to be settled.

It’s a good idea to speak to your home insurance provider first, and compare policies and check exclusions before you buy any new additional cover.

Will having an extension increase my home insurance premium?

Yes, this is likely. Once your home extension is finished, your home will be bigger and so the rebuild cost will have increased to reflect this.

Plus, to give the final finishing touches to your new space you’ll probably need to buy new furniture, fixtures and fittings.

All of this means the value of your home and its contents are likely to be higher, so your premium will reflect this.

How can I reduce the cost of my home insurance premium?

Consider increasing your voluntary excess. This is the amount you agree to pay towards a claim in addition to the compulsory excess set by your insurer. Paying a higher voluntary excess usually means a cheaper premium. But only choose an amount you can realistically afford.

Improving your home security by installing a burglar alarm and approved locks can also help.

Frequently asked questions

You'll need to check with your local council’s local planning authority for its rules and regulations.

Most extensions fall into what’s called ‘permitted development’, which don’t require planning permission. However, for this to be the case, the extension has to adhere to certain limits and conditions. These will usually relate to the height and depth of the proposed extension, as well as where you’re looking to build it.

Employing an architect to draw up plans for a major project that affects the structure of your home can give you peace of mind that the project is safe and conforms to legal requirements. An architectural designer or technologist can also help with this. You’ll have to pay a fair amount for their expertise and aptitude for design, though.

Alternatively, a trusted, experienced builder can draw up plans. This could be suitable if you’re looking for straightforward designs. But you should speak to previous clients and see examples of their work before deciding.

Your builder should have their own insurance. But levels of cover vary so you may not be protected in all instances.

For example, damage to your own building may not be included in their policy. So if their work causes an existing wall in your home to collapse, it could be up to you to prove negligence. Otherwise, you’d have to pay to repair the damage yourself.

If your builder’s insurance policy doesn’t include public liability cover, you could be held liable for damages if something happens. For example, if a passer-by or neighbour got hurt during the build, the injured person could make a claim against you, as the builder’s employer.

This is where taking out renovation insurance can help ensure all gaps are filled and you have peace of mind whilst the work is happening.

It depends on your insurer and policy. If yours excludes cover for alteration and renovation projects, you’ll need to either pay extra for your insurer to include it. Or take out a new home renovation and extensions policy while building work is taking place.

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