RBC says that if current trends continue, single detached homes in Toronto and Vancouver will soon be firmly in the luxury housing segment, available only to wealthy households.
In its latest housing affordability report, RBC says trends continued to vary widely between the country's various real estate markets in the fourth quarter of last year.
Nationally, RBC says housing affordability deteriorated slightly, by 0.6 percentage points to 46.7 per cent, in the final quarter of 2015, driven by price gains in Vancouver and Toronto.
Affordability declined in both the single detached and condo categories.
RBC says purchasing a single, detached home in Vancouver is already out of reach for the vast majority of families. Conditions in Toronto are similar, though not as drastic.
The condo market is still within reach for many first-time buyers in Vancouver and Toronto, although that segment of the market also became somewhat more unaffordable in the fourth quarter.
That's in contrast to other regions of the country, particularly the Atlantic region, where affordability improved in certain markets, and Alberta, where affordability was flat as house price declines were offset by rising unemployment.
RBC's housing affordability report looks at the proportion of the median household income that would be needed to cover the cost of mortgage payments, property taxes and utilities, based on the median market price for homes.
The measure is based on a 25 per cent down payment and a 25-year mortgage loan at a five-year fixed rate.