If I leave my window open during heatwave am I still insured against burglary in France?

Reader Question: Due to the current heatwave we have kept our windows open at night, but it caused me to wonder - are we at risk of not being covered if we are burgled? How can I know? 

Keeping your windows open overnight can be beneficial during periods of warm weather, but can increase your risk of burglary – and prevent you from being covered by your insurer. 

The first thing to note is that theft is usually, but not always, covered under your home insurance policy through assurance vol (theft insurance).

Theft insurance is typically not included as-standard in basic policies, but is usually part of more comprehensive multirisques habitation cover. 

This is not guaranteed however, so check your policy closely to see what you are covered for.

Your policy will provide an outline for what is included under assurance vol, but this generally includes coverage following:

• a burglar breaking and entering, (par effraction), 

• scaling a wall, or fence to enter your property,

• entrance through threats, violence, or clandestine measures, 

• usually entrance via a stolen or lost key (this is sometimes excluded)

It will also list a series of exemptions where policy holders are not covered, including theft by family members or people staying at your home, failing to follow the correct procedures of your security apparatus (not setting alarms correctly, etc), or being vacant from your home for an extended period (usually 90-plus days consecutively or across the year but in certain circumstances coverage can be lost after 30 days of absence). 

Gross negligence clause

There is also typically an exclusion for négligence manifeste or gross negligence.

Government guideline website Service-Public.fr gives examples of this clause including leaving doors open or failing to lock them, failing to keep valuable goods in a safe space, etc. 

This is not a comprehensive list however, and more specific circumstances will be listed in your policy document.

One form of gross negligence listed may be leaving your windows open as it allows burglars a direct entry into your property without needing to force entry. 

Insurers including Cardif (insurance wing of BNP Paribas) and VYV Conseil explicitly list ‘fenêtre non fermée’ as an example of gross negligence.

Leaving an opening to your property also nullifies coverage from burglars entering par effraction, as they did not need to pick a lock, break a window, etc, to enter. 

Sometimes, proof of a burglar breaking and entering is required by your insurer as part of a claim, and a burglar entering through a window would leave no trace of this.

Even if leaving a window open is not specifically stated as an act of gross negligence by your insurer, it may be classified as such if it allowed open access to your property.

A 2026 ruling from the Cour de Cassation, France’s highest judicial court, confirms that an open window can absolve an insurer from their liability. 

The case revolved around a couple who had their cars stolen after a burglar entered their home through an open window and stole the vehicles’ keys. 

The insurer denied the couple coverage based on the window being left open, arguing that its guidelines stated a theft committed via stolen keys was only covered in an instance of “[keys that] had been stolen: from a residential building, provided the building was entered surreptitiously despite its access points being locked and other openings closed.” 

The couple argued that the policy was general and did not explicitly state ‘open windows’ were an exclusion clause that voided coverage.

The court however ruled that open windows did not need to be specifically highlighted as an exclusion clause.

As the open window meant the car keys were not securely locked away, it voided the assurance vol clause. 

Rulings from the Cour de Cassation are generally used to set a precedent in future cases, and this is no different – insurers who refuse to cover burglaries through an open window in summer could point to the case as proof that windows constitute an opening to the property.