Do I have to report a renovation to my buildings insurance?

What renovation and cover during the works cost, based on published figures.

What matters is whether the value of the house or the risk changes. A converted loft, an extension or a conservatory add living space and raise the rebuilding cost. Underfloor heating, a heat pump or high-end bathrooms raise the standard of fittings.

A change of use counts too: a holiday flat, an office with clients visiting, or the house standing empty for months during the renovation.

German insurance law requires you to report an increase in risk. If you fail to, the insurer can reduce payment depending on how much you are at fault, and in the worst case refuse it for that claim.

Underinsurance is more common: the extension is there but not insured. Money is then missing for rebuilding, and an agreed waiver of underinsurance can fall away because your details are no longer correct.

Buildings insurance protects the existing house against fire, burst pipes, storm and hail. It does not cover theft of building materials, vandalism or faulty work by tradespeople on the new part. That is what construction works insurance (Bauleistungsversicherung) is for.

If someone gets hurt on your site, you are liable as the client. Personal liability insurance often covers smaller projects up to a building cost of about EUR 100,000. Above that you need builder's liability insurance (Bauherrenhaftpflicht).

In many countries you set a rebuild figure yourself and update it when you remember. German policies usually keep pace with building prices on their own, through the 1914 value or through living space. That automatic update only works on the house you described when you signed. An extension you never reported is not part of it, however much the index rises.

Correspondence with the insurer will usually be in German. Keep a copy of your report and the insurer's written confirmation with your policy, so nobody has to argue later about what was known.

Maintenance that keeps the house as it is needs no report: painting, new flooring of the same quality, or swapping an old boiler for an equivalent one.

If your policy is priced by living space and the space does not change, the premium often stays the same. A short written notice still does no harm, because it gives clarity if you ever claim.