It also found that a quarter of property owners are invalidating insurance by planning to take down walls themselves rather than enlisting the help of a professional tradesperson.
David Rochester, head of underwriting at Halifax Home Insurance, said: "Any damage to a weight-bearing wall that results in ceiling collapse or other damage could also invalidate a buildings insurance policy.
"They should also seek building regulations advice from their local council or risk difficulty trying to sell their home further down the line."
Nationwide's campaigns manager Charlotte Sjoberg has recently stated that buildings and home contents insurance are equally important for property owners.
She added that both types of cover play "a really important" role in protecting homeowners.
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