Proposed Toronto "iceberg" mansion would be built mostly underground

A Toronto property owner is looking to build a new mansion that would be largely underground — an increasingly popular style commonly known as an “iceberg home.”

The proposed home, set to be located at 7 Knightswood Road in Toronto’s Hogg’s Hollow neighbourhood, received approval from the Committee of Adjustment late last year. The property owners, wanting to build much deeper underground space than is allowed until current bylaws, had to seek out a zoning variance.

The plans call for underground portion of the home to reach just over 27 metres below the property’s surface. This is roughly 8 metres more than the permitted 19 metre depth. The home’s length would also extend 10 metres more than is allowed under City bylaws.

Rendering of the proposed home. (City of Toronto)

The above-ground portion of the home would stand 8.3 metres tall, just over the permitted 7.5 metres.

The committee approved the variances during a November 19 meeting despite hearing from neighbours who expressed concerns over the scope of the home being inconsistent with the established neighbourhood. The neighbours also raised concerns about the negative environmental impact of making so much of the property’s underground space impermeable.

City Councillor Jaye Robinson similarly voiced concerns over the potential environmental issues, tweeting “The environmental impacts of ‘iceberg houses’ – including reduced soil permeability, soil erosion and stormwater runoff – are well documented. These types of new builds are a blind spot for the City – this needs to change.”

Robinson has said she will raise the issue during the next City Council meeting.

Construction on the home has not yet started, but a 250-year-old tree was cleared from the property earlier this year, upsetting some neighbours.