The heritage designation in London is being challenged when it comes to buildings and their historical significance.

Mid-century modern buildings built between the 1950s and 1970s are about to start appearing on the heritage registry at city hall, protecting them for future generations.

The Crown Trust Building on Queens Avenue is one of many in the city stuck in a void - too new to be seen as old enough for preservation.

The architectural style is called mid-century modern, constructed between the 1940s and 1970s, with geometric shapes, large windows and modern materials.

A call is going out to start protecting the best examples in London.

Sandra Miller of Forest City Modern wants the style included on the city's inventory of heritage resources. The Ontario Heritage Act doesn't have an age requirement for heritage protection. Even a new building of significant architecture or impact can be protected.

“We don't think of them as heritage buildings, but of course time marches on and so does our definition of heritage,” Miller says.

Miller's report to the advisory committee on heritage identifies 19 examples of mid-century modern buildings in London that she recommends adding to the heritage register.

The register is the first phase of protection - requiring a second opinion from experts before demolition permits could even be issued.

“Middle age is certainly a dangerous time for buildings of any era," she says.

Miller says there are probably many more examples of mid-century modern architecture available in the city for consideration. Anyone who knows of an example, including houses, should contact the heritage committee at city hall so they can be considered.