75% – or around nine million – of insured UK homeowners may have accidentally invalidated their home insurance policy since moving in, according to a study from Confused.com.

The study surveyed 2,000 UK homeowners. They investigated seemingly normal things people do in the summer that may result in no payout from their insurance providers, should something happen. According to the research, the majority (75%) of UK homeowners have done something that risks voiding their insurance policy.

Sleeping with the windows or doors open during summer is the most common risk, with almost half (48%) of insured homeowners confessing to this. The Midlands cities of Birmingham and Leicester see the most homeowners taking this risk, with nearly 2 in 3 (63%) each. Both cities also place in the top 10 for break-ins in the UK. Birmingham ranks third with 6 burglaries per 1,000 people, while Leicester ranks ninth with 4 burglaries per 1,000 people.

14% of homeowners post photos of their holiday on social media while they’re still away. Doing so can jeopardise your home’s safety, as potential burglars could know your home is unoccupied, and therefore easier to enter.

Younger generations are most likely to be guilty of sharing their holiday pictures on social media too early. 31% of 25-34 year old homeowners have shared holiday photos while still abroad, compared to 8% of over 65s. Additionally, 18-24 year old homeowners are most likely to leave their homes unoccupied for longer than their policy’s ‘days unoccupied limit’. 22% of those in this age bracket have left home long enough to invalidate their home insurance.

Overall, three in four homeowners have risked invalidating their insurance. Other common actions include accidentally leaving doors unlocked (20%) and losing a key to your home (9%).

Matthew Harwood, home insurance spokesperson at Confused.com, said: “When you spend time at home during the warmer months, it’s understandable to want to sleep with windows or doors open to keep cool. But you should always avoid leaving doors unlocked, and if windows must be left open, then invest in window restrictors. This is a safety device that stops your window from opening past a certain point.

“And while we know it’s fun to share photos of your holiday while you’re away, many homeowners don’t know this risks invalidating your insurance. Waiting to post any holiday photos until after you get home stops people knowing your home’s unoccupied.

“If you are going on holiday over the coming months, you should check your insurer’s ‘days unoccupied limit’. Leaving your home empty for an extended period can increase the risk of burglary, and invalidate your insurance. These are typically 30, 60, or 90 days. If you need to leave your home for longer, you should contact your provider to change your cover or get a permit for this period.”