Garden Suite Foundation Options in Toronto

In short: a garden suite in Toronto usually sits on strip footings with short foundation walls, concrete piers, or a slab, depending on the design, the soil and what’s nearby. All of them have to be protected from frost and built to the permit drawings.

Foundation options for a garden suite

Strip footings and foundation walls

A continuous footing below frost depth with short concrete walls on top. It’s the most common choice for a full garden suite and gives a solid base for the framing.

Concrete piers

Concrete columns down to firm soil, with beams on top. Useful near trees, where digging a full trench would damage the roots, or where the ground slopes.

Slab on grade

A reinforced concrete slab with a thickened edge, protected from frost. It can be simpler where the design allows it.

The engineer and designer choose the type. We form and pour it.

Things that affect a garden suite foundation in Toronto

• Frost. Footings in Toronto need to be about 1.2 metres (4 feet) below grade, or protected another way the design allows.
• Trees. Toronto protects many trees, and the suite’s foundation may need to stay out of a tree’s root zone.
• Access. Rear yards are often reached only by a narrow side path, so concrete may need a line pump or a boom.
• Drainage. The suite shouldn’t send water toward the house or the neighbours.

Are garden suites allowed in Toronto?

Yes, in most low-rise residential zones since 2022 (By-law 101-2022). Laneway suites have been allowed citywide since 2019. Both need a building permit.

Questions people ask

Does GSS build the whole garden suite?

We build the structure: the foundation and the framing. See our garden suites and laneway houses page.

Which foundation is cheapest?

It depends on the soil, the trees and access. The right one is the one that suits your lot and passes the permit.

Planning a garden suite?

Send us the drawings and the address. Get a free quote or call (416) 785-7838.