Toronto moves to limit ‘iceberg homes’ amid tree, stormwater and construction concerns
City staff propose new zoning limits on deep basements after complaints about tree loss, drainage and excavation impacts. Council will revisit the rules in January.
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By Torontoer Staff
Toronto planners are recommending new zoning controls to curb so-called iceberg homes, the detached houses with more living area below ground than above. Officials say multi-storey basements are creating environmental and construction problems in low-rise neighbourhoods.
A staff report to the city’s Planning and Housing Committee proposes minimum below-ground setbacks and other changes to protect the tree canopy and local stormwater systems, while responding to complaints about excavation nuisance and property impacts.
What defines an iceberg home
Iceberg homes build heavily downward, with large basements that can contain recreation rooms, gyms or indoor parking, often across multiple storeys. By expanding below grade, developers and homeowners can increase usable floor area while appearing to comply with height and density rules applied above ground.
Why city staff want limits
An April 2025 staff report says deep basements can harm mature trees, reduce opportunities for new planting, decrease soil permeability and complicate drainage, groundwater and stormwater management. Officials also flagged embodied carbon from extensive excavation and construction as a concern tied to the city’s climate resilience goals.
Potential impacts of iceberg homes include those related to injuries to mature trees, limitations on new planting opportunities, soil permeability, drainage, groundwater and stormwater management, and embodied carbon.
City of Toronto planning staff, April 2025 report
Staff are proposing zoning by-law changes that would introduce minimum below-ground building setbacks for low-rise houses and multiplexes, preventing sprawling basements from extending to the property line and limiting excavation close to neighbouring lots.
Neighbourhood impacts and precedent cases
Although the number of formal applications remains small, neighbourhood groups and environmental advocates say the builds can have outsized effects. Critics point to foundation damage, shifting ground levels and excessive noise and vibration during deep excavation.
The 2021 Hoggs Hollow controversy is often cited as a cautionary example. Construction of an iceberg-style build there led to the removal of a 250-year-old sugar maple and other mature trees in a ravine area, prompting a municipal review of how such projects affect local ecosystems and neighbours.
- Tree loss and reduced canopy cover
- Changes to soil permeability that increase runoff risk
- Pressure on stormwater and groundwater systems
- Noise, vibration and risk to neighbouring foundations during excavation
- Higher embodied carbon from extensive below-grade construction
A City of Toronto spokesperson told the Toronto Star that 12 iceberg home applications were submitted since spring 2024, a sign the issue is drawing enough attention to require policy response.
What residents and advocates want
Volunteer groups argue iceberg proposals reflect limits on above-ground expansions in many residential zones, pushing homeowners to seek more space underground. They say broader changes to housing rules could address the underlying demand that drives these builds.
This is not the sign of a city with a healthy housing policy, and as noted by City Planning, these buildings are not good for the tree canopy.
More Neighbours Toronto, letter to City Council
More Neighbours Toronto urged planners to consider raising height limits in residential zones so owners would not feel compelled to expand downward. City planning staff acknowledged the connection between above-ground restrictions and the underground trend in their analysis.
Next steps
City staff will return with formal recommendations in January, when councillors will have the opportunity to debate and revise the proposed zoning changes. Any amendments would aim to balance homeowners’ rights to add living space with protections for trees, soil and neighbouring properties.
The proposed below-ground setbacks are a targeted first step. Council could pursue additional measures, including clearer construction standards, monitoring of excavation impacts and broader reviews of residential height and density rules.
Toronto’s approach will be watched by other municipalities facing similar builds, as cities weigh how to expand housing supply while safeguarding neighbourhood environments and infrastructure.
housingcity-planningenvironmenttreesdevelopment
