Homeowners told to do this one window check before June 1 - or risk £1k mistake

Some experts are warning that invisible could cost households hundreds in ruined interiors over the summer. According to My Home Improvements, many double-glazed windows-especially older ones-do not contain UV-blocking layers or coatings, leaving homes vulnerable to the stronger rays of June and July

This could cause bleaching, cracking and fading to anything in direct light - from wood flooring to artwork, fabric sofas and even wallpaper, at a total cost of between £1,000 and £2,000.

My Home Improvements said UV levels rise significantly in June, with long daylight hours and direct sun hitting interior spaces through south- and west-facing windows.

It pointed out this period often coincides with people removing curtains or blinds to let in natural light - unintentionally increasing exposure and UV damage doesn't appear overnight - but still can cause irreversible fading in as little as a few weeks of strong sun.

A spokesperson said: "By the time you notice your oak flooring or velvet chair has lost its colour, it's too late."

"And replacing or repairing these items can easily run into the hundreds or even thousands."

Homeowners can protect their furnishings, flooring and curtains from UV damage by placing UV film on their windows, which can cost from just a few pounds per square meter.

My Home Improvements estimates the cost of replacing UV-damaged flooring at £200 to £600 and the cost of reupholstering a sofa at between £500 and £1,000.

Paint and wallpaper would cost between £80 and £300, while damage to curtains and blinds would set homeowners back £150 to £500 to rehang and fix.

"You wouldn't sunbathe without sunscreen - and your interiors are no different," says .

"Checking now, before the first full blast of summer sun, is the smart move. A single sheet of film could save your home from hundreds in sun damage."