Most people arranging an extension assume two things: that their existing buildings insurance continues to protect the house, and that the builder’s insurance covers the rest. Both assumptions are usually wrong, and the gap between them is where the money is.
Why your home insurer steps back
A standard home insurance policy is written for a finished, occupied house. Once you start structural building work, the risk profile changes completely. There are open walls, temporary supports, trades coming and going, materials stacked in the garden and, for a period, no weathertight envelope.
Insurers respond to that in different ways. Many restrict cover during the works. Some exclude it. Some will withdraw cover altogether if they were not told, which is the worst outcome of the three because you only discover it when you claim.
The single most important thing to understand: if a wall collapses while an opening is being formed, standard buildings insurance will not normally cover you.
Tell your insurer before anything starts
Contact your home insurer before work begins and tell them what is planned, how long it will take, the value of the works, whether you will be living there, and who is carrying out the work. Get their position in writing.
They will usually do one of three things: continue cover with conditions, restrict cover to specified perils, or step back from the works entirely and expect a separate policy to sit alongside. Whichever it is, you need to know before the first wall comes down, not after.
What extension insurance actually covers
Extension insurance is built for the period when a house is a building site. The important point is that it is not just the new extension that needs protecting. The existing structure being extended, usually your home, is exposed as well.
Cover typically includes:
- The existing structure and the new works, including temporary works.
- Public and employers’ liability. Injury to contractors, visitors or neighbours.
- Fire, theft and storm damage to materials, plant and equipment on site.
- Plant, tools and equipment, owned or hired in.
- Party wall contractual liability where the works are near a boundary.
The policy summary sets out the main cover headings in full.
When cover needs to start
Before work begins. Not when the extension starts going up.
The riskiest phases are often the earliest: demolition, excavation, and forming openings in the existing structure. A policy that starts once the shell is up has missed the part of the job most likely to produce a claim.
Think about the end date too. Projects overrun, and cover that expires mid-build leaves you exposed at exactly the wrong moment. Protek policies can be extended on a short-term basis if the programme slips, which is far easier than arranging something new halfway through.
Occupied or unoccupied
Both are insurable, but they are different risks and your insurer needs to know which applies. If you move out for the duration, say so. An unoccupied property carries higher risk, and an undisclosed change in occupancy is the kind of detail that causes problems at claim stage.
Using a main contractor does not transfer your exposure
This is the most common and most expensive misunderstanding. Your contractor’s public liability insurance covers their liability. It does not cover yours, and it does not cover your house.
Even with a competent main contractor running the job, you remain exposed in respect of the existing structure. And if you are managing the project yourself, the responsibility for the site and everyone on it sits with you.
Always ask to see your contractor’s certificate, check it is current and the limits are sensible, and keep a copy. Then insure your own position separately.
If you are building near a boundary
Extensions frequently trigger the Party Wall etc. Act 1996, particularly where you are excavating within three or six metres of a neighbour’s foundations or cutting into a shared wall. Under the Act your neighbour has a right to be compensated for damage caused by your works whether or not it was foreseeable, which is not what general public liability cover is designed for.
Party wall contractual liability can be included within a Protek site insurance policy, subject to you serving the correct notice and having a condition survey carried out. Our Party Wall Act page covers the requirements.
Do you also need a structural warranty?
A structural warranty is a different product doing a different job. Site insurance protects the project during construction. A 10-year structural warranty covers the completed building against defects in design, materials, and workmanship after you finish.
For a straightforward extension on an existing home you may not need one. Where the work is substantial, where you are creating a new dwelling, or where there is lending involved, a warranty is usually either required or well worth having. Most mortgage lenders will expect one.
Getting it arranged
Have the conversation with your home insurer early, get their position in writing, and put the right cover in place from the day the first tool arrives.
You can read more on our extension insurance page, get a quote online in a few minutes, or call the team on 0333 456 8030 if you would rather talk it through.
