A growing demand for condominiums in major cities such as Toronto is sending housing starts to 10-year highs in Canada, but economists are warning the growth will not continue.

Canada Mortgage and Housing Corp. said housing starts hit their highest level in almost 10 years in November, but the growth is extremely uneven, with construction of condos accounting for the lion's share of the growth while building of detached homes is lagging.

In the Toronto region, which is steering the national trend, condo starts climbed 141 per cent in November compared to a year earlier, while detached home starts fell by 32 per cent, CMHC said.

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The trend for new construction homes seems out of step with the recent weakness for resale homes in the Toronto area, but Canadian Imperial Bank of Commerce economist Avery Shenfeld said the growth in housing starts "doesn't clash as much with other Canadian housing indicators as you might think."

Mr. Shenfeld said builders are focusing on the less-expensive condo sector because of strong demand from buyers who cannot afford detached homes.

Much of the current condo construction also comes from units that were pre-sold during hotter times."It's going to be a while before quieter sales offices mean fewer cranes on the horizon," he said in a research note on Friday.

Mr. Shenfeld said booming condo starts in November could also have been fuelled by mild weather in most of the country, with Ontario starts climbing 66 per cent in November compared to October.

On an annualized basis, CMHC said Canada has seen 252,184 housing starts this year as of November, an unexpectedly large jump from 222,695 starts on an annualized basis at the end of October.

Bank of Nova Scotia economist Derek Holt said the consensus estimate from economists had been a drop to about 213,000 starts in November, but the market continued to boom.

"You'd have to go back to 2007 to get stronger construction starts," he said in a research note.

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Mr. Holt said he is not confident the condo construction trend will continue at the same pace. He feels future sales will be hurt by Ontario's announcement in April of expanded rent control measures that will sharply limit the amount landlords can increase rents on all types of units, including new buildings.

"Given project lags, the numbers we're seeing reflect decisions that pre-date rent control changes in April that many feel will sharply diminish investor appetite for such units," Mr. Holt warned.

Mr. Shenfeld also foresees new construction slowing, forecasting it will contribute to economic growth in Canada in the next couple of quarters, but will be "a significant drag" by 2019 as activity slows.

CMHC chief economist Bob Dugan said he is not concerned that the condo sector in Toronto is expanding too quickly, noting demand is still strong.

"Evidence of overbuilding is low due to the decreasing inventory of completed and unabsorbed multiple units and strong demand," he said in a statement.

Actual November starts in Canada, on a non-seasonally adjusted basis, were up 38 per cent compared to November last year, CMHC said, driven by 66-per-cent growth in Ontario due to a condo construction boom.

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In British Columbia, starts climbed just 4 per cent in November compared to a year ago.

CMHC said starts were lower in Vancouver in November mostly because the construction sector is at full capacity, so fewer condo and rental projects are launching in the City of Vancouver, Richmond and on the North Shore. In Burnaby and New Westminster, multiple-family starts are higher so far this year.

Bank of Montreal economist Robert Kavcic said trends in housing starts are reinforcing a long-standing theme of population growth in Canada's biggest cities. A record 175,000 apartment and condo units were started this year in urban centres with populations of more than 10,000 because many cities face development constraints that push most of the new supply into this form of housing.