Toronto city staff are moving to crack down on a controversial style of luxury housing with vast underground square footage, known as "iceberg homes," under fire for their noisy construction and impacts on local trees. As its name suggests, an iceberg home has most of its square footage below grade. Historically, the designs have emerged as a way to work around zoning limits on height and density to allow homeowners (often in affluent, low-rise neighbourhoods) to add substantial square footage without building upward. In a Nov. 18 report and presented to Toronto's Planning Housing Committee earlier this month, staff proposed changes that would regulate how far below-ground portions of low-rise residential buildings could extend. The recommendations would introduce minimum underground building setbacks for houses and multiplexes, although apartment buildings would be exempt. Currently, Toronto's zoning bylaws do not control below-ground setbacs for small residential buildings, which has made multi-storey basements possible. A City of Toronto spokesperson told the Star that 12 applications for "iceberg homes" have been submitted since 2024, and while that number seems relatively low, the homes have continuously drawn concern from neighbourhoods and environmental advocates, especially in areas with mature tree canopies. In the report, City staff flagged several issues with the properties, including the loss of mature trees, impacts on neighbourhood properties during excavation, and the amount of concrete required. The committee deferred the report to its January meeting after a councillor requested more information from staff. Despite their limited presence, iceberg homes have already proven controversial in Toronto. Back in 2021, a planned iceberg home in Hoggs Hollow sparked outrage after several trees (including a 250-year-old sugar maple) were cut down to make way for the build. Later that year, City Council voted to explore the impacts of iceberg homes. The housing phenomenon isn't unique to Toronto either, and these multi-storey properties have become quite common in London, England, where height limits in historic communities have led some wealthy homeowners to build downward instead of up. There, researchers and journalists have also combed through council planning documents to find the lavish amenities proposed for certain iceberg homes , including swimming pools, gyms, Turkish baths, wine cellars, panic rooms, and even an artificial beach. In a letter to Toronto City Council , volunteer-run housing advocacy group More Neighbours Toronto stressed how the trend of iceberg homes has proven how difficult it's become to add housing above ground. "We believe it is worth considering why iceberg homes are starting to be proposed in the City of Toronto. People are finding it too difficult to build new housing above ground, and so are increasingly looking to add it underground," a letter from the organization reads. "This is not the sign of a city with a healthy housing police, and as noted by City Planning, these buildings are not good for the tree canopy. We encourage City Planning to consider increasing height limits in residential zones so that iceberg homes stop being necessary." City staff are set to revisit the issue in January.