Toronto looks to limit size of underground floors in 'iceberg homes' | CBC News

"Toronto is closer to placing restrictions on the size of iceberg homes, a controversial style of luxury development with massive basements that have drawn environmental concerns over impacts on flood risks and the city's tree canopy. Iceberg homes are multi-storey residences that take up more space below ground than above, usually to increase square footage when zoning height restrictions prevent building up. The city's housing and planning committee voted Thursday to adopt a motion that would introduce minimum underground building setbacks for low-rise residential buildings,"

"A city report to the committee found iceberg-style basements reduce soil health and tree growth, and make the ground less permeable to storm water, increasing flood risks. Both storm water run-off and tree canopy growth have been major issues in the city in recent years. Reducing impermeable surfaces like paved lots was something Mayor Olivia Chow wanted the city to look at following major flooding in 2024."

"Toronto also has a target to increase its tree canopy to cover 40 per cent of the city by 2050 to help fend off the worst heat effects from the climate crisis. Other issues flagged in the city staff report on iceberg homes include excavation impacts on neighbouring properties, reduced area to plant new trees, and the high carbon footprint that comes with the amount of concrete required to build them."

Toronto is moving to restrict iceberg homes by introducing minimum below-ground setbacks for low-rise residential properties. Iceberg homes extend more square footage below ground than above, often to circumvent height limits. Iceberg-style basements reduce soil health and tree growth, decrease ground permeability to storm water, and increase flood risks. Toronto currently lacks below-ground setback requirements. Stormwater run-off and declining tree canopy have been significant urban issues, and reducing impermeable surfaces gained urgency after major 2024 flooding. Additional concerns include excavation impacts on neighbouring properties, reduced planting area, and the high carbon footprint from extensive concrete use.

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