Some of the most expensive and densely developed land in Vancouver has been designated as flood plain, including a significant area around False Creek, a new map issued by the city Thursday reveals.

And an amended building bylaw raises by roughly one metre — to 4.6 metres — the level of construction for new homes within the flood plain, anticipating impacts of climate change such as rising sea levels.

While the designation is not expected to affect property values, it will likely make new homes more expensive due to increased construction costs, and will alter the transition between public roads to parking lots in highrise buildings.

“Of course, (construction) will be more costly,” said Lynn Harrison, chairwoman of the Greater Vancouver Home Builders’ Association. “I don’t know if it will be significant, but it certainly will be a concern. Any time you add more cost, it makes (housing) more expensive.”

But it’s not just the costs that are of concern.

“The challenge is that by changing this level to 4.6 metres, a lot of roads in the area were built to a different standard and that will definitely cause concern with the transition between the street and the buildings,” said Harrison.

“They’ll have to be looking at ramps,” she added, although she couldn’t say how the change might impact underground apartment parking lots. “The road is built to one standard and now they raise that level up (for the building). There’s a metre difference in the level. It’s really about the transition; that’s the challenge.”

The report, which will now be considered by council, proposes to raise the flood construction levels (FCLs) in the designated flood plain areas, including False Creek, the north arm of the Fraser River, and parts of Point Grey, Kitsilano, English Bay and land along Burrard Inlet. This change would only affect new building or major reconstruction projects, is not retroactive and would have a “negligible impact on the overall cost of building projects,” the report noted. “Increasing FCLs now to improve the flood resilience of new buildings throughout their lifespan is a cost effective tool that can be applied while further adaptations are carefully considered.”

It cites a provincial study that estimates the cost of building flood-protection infrastructure needed by the year 2100 in Metro Vancouver — from the coastal shoreline as far east as the Port Mann Bridge — at $9.5 billion. By raising the FCLs, the report states, the city hopes to take a “proactive approach” in a bid to prevent future flood damage and avoid some of these projected infrastructure costs.

“Current flood risk in the City of Vancouver is manageable but with observed and projected trends in sea level rise ... the risk is anticipated to increase significantly during the lifespan of buildings being developed now.”

The authors state that the Insurance Bureau of Canada indicated it does not expect increased FCLs to change insurance premiums. “Research on house values shows that actual flood events cause impacts on insurance premiums rather than the location of the home being included in an expanded flood zone; therefore we do not expect that the publishing of a flood map will impact home values.”