Housing in Canada became harder to afford in the second quarter, with Vancouver's pricey market playing a major role in the deterioration, according to a report by Royal Bank of Canada on Monday.

It was the second straight quarter in which the bank's quarterly Housing Trends and Affordability Index dropped. The cost of housing rose nationally across all the housing types the index tracks in the second quarter.

The index measures the proportion of pretax household income needed to service the cost of owning a home. A rise in the measure indicates a loss of affordability.

For a detached bungalow, the measure rose 1.7 percentage points to 43.3 percent. For a standard condominium, it edged up 0.8 percentage points to 29.2 percent, and for a standard two-storey home it climbed 1.8 percentage points to 49.3 percent.

Vancouver, which has long seen exceptional growth in home prices compared with other Canadian cities, directly accounted for up to one-third of the deterioration in affordability on the national score, the RBC report said.

"Vancouver's housing market is without a doubt the most stressed in Canada and is facing the highest risk of a downturn," said chief economist Craig Wright.

Other local housing markets were reasonably affordable or at worst, slightly unaffordable, the report showed.

Housing sector observers generally see the overall pace of housing activity, from starts to resales, slowing in the coming months, partly due to tighter mortgage regulations introduced earlier in the year and as pent-up demand gets absorbed.