Sales of condos and townhomes could soften in Canada's two largest housing markets as first-time buyers face tougher lending rules that take effect on Monday.

The mortgage changes will likely be felt especially hard in Greater Vancouver and the Greater Toronto Area, according to the Canadian Real Estate Association.

"First-time home buyers, particularly in housing markets with a lack of affordable inventory of single-family homes, may be priced out of the market by the new regulations that take effect on Oct. 17," CREA chief economist Gregory Klump said in a statement on Friday.

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He made the comment as CREA released data showing the average price for various housing types sold nationally in about 100 markets in September reached $474,590, up 9.5 per cent from the same month in 2015. Sales volume increased 4.2 per cent.

Last week, the federal government announced measures to tighten mortgage rules. Ottawa is also closing tax loopholes used by some foreign buyers.

In most cases, homeowners who are looking to upgrade to larger houses must first sell their existing properties before they are able to acquire their next place.

"First-time home buyers support a cascade of other homes changing hands, making them the linchpin of the housing market," Mr. Klump said. "The federal government will no doubt want to monitor the effect of new regulations on the many varied housing markets across Canada and on the economy, particularly given the uncertain outlook for other private-sector engines of economic growth."

CREA noted that the average price for various types of housing sold in Greater Vancouver in September reached $864,566, compared with $755,755 in the GTA. The price for detached houses last month in Greater Vancouver averaged $1.53-million, compared with $1.01-million in the GTA.

Industry experts say the GTA has a wider variety of residential options for home buyers to choose from, notably semi-detached properties and rowhouses, compared with Greater Vancouver. Detached houses sold in the City of Vancouver recently averaged more than $2.6-million – double the price of those in the City of Toronto.

In February, the B.C. government unveiled a new tax on properties in the province that sell for more than $2-million. The provincial government also implemented a B.C. tax on purchases by foreign home buyers in the entity known as Metro Vancouver, effective Aug. 2.

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"Detached houses in Vancouver will still be out of reach for the vast majority of working families. So, what other kinds of supply can we bring to the market? We need to look at building more three-bedroom condos and townhouses near transit," Jonathan Cooper, Macdonald Realty Group's vice-president of operations, said in an interview.

CREA said nine of the 11 metropolitan markets that it tracks through its home price index showed gains in September from the same month in 2015. Benchmark prices, used by the industry to represent typical existing properties sold, fell in Calgary and Saskatoon. The overall benchmark price for the 11 markets hit $576,100 last month, up 14.4 per cent from a year earlier.

Robert Hogue, senior economist at Royal Bank of Canada, said the moves announced last week by federal Finance Minister Bill Morneau to cool the housing market will generally dampen sales across the country.

"We believe that the new measures – that include more stringent and uniform qualifying rules for mortgage insurance across mortgage types – will both speed up and harden the landing that we previously expected to occur in the year ahead, although they are unlikely to cause a crash," Mr. Hogue said in a research note.

Average home prices have flattened in Greater Vancouver but they remain on the rise in the GTA.

"The picture emerging from the September statistics is in line with our earlier assessment that Canada's housing market is down to only one major 'heat source' – Toronto – with Vancouver now quickly losing some of its heat," Mr. Hogue said.