This week's 'Explainer' goes over the so-called 'missing middle', a housing density term that has caught the attention of city planners and residents of Toronto, as well as other cities around the world. Here in Toronto, the rather dramatic shifts between new high-rise tower and older single-family homes puts the scarcity of more gentle density in stark relief. So why is the middle missing, and how can developing it improve quality of life within the city? Our sister site, SkyriseCities, has the answer:

Missing Middle Housing types, image via Opticos Design

Rapid post-war development in North America has created a tale of two densities and extremes of housing that have dominated the cityscapes of the continent's biggest cities. Highrise condominiums and apartments are fulfilling a demand for comparably inexpensive living within urban enclaves, while single-family housing has exploded in the suburbs, creating a built form characterized by large lots and automobile dependency. But the sweet spot in the middle has been lost in the shuffle, leaving little room for the gentle densities that defined neighbourhoods before the Second World War.

You can find the rest of the story on our sister site, SkyriseCities.com.