Is a basement apartment or a garden suite cheaper to build?

A basement apartment is typically $80,000–$175,000, roughly two to three times cheaper than a garden suite at $200,000–$300,000+, because it reuses the house’s existing foundation, roof and utility connections instead of building them new.

How much longer does a garden suite take to build than a basement apartment?

A basement apartment typically takes 3–5 months from design to occupancy. A garden suite typically takes 6–12 months, since it is new construction requiring its own foundation and servicing.

Basement vs. garden suite

Same goal, two very different builds.

A basement apartment and a garden suite both give you a second, legal, self-contained home on your property. That’s where the similarity ends. One works inside a structure you already own; the other is new construction from the ground up.

Cost
Timeline
Zoning
Servicing
Privacy

Book a consultation Confused by the terms?

Which one fits?

Four questions. One lean.

01What matters most?
02Budget for the build?
03Basement has decent ceiling height and room for an egress window?
04Backyard has room for a unit, with setbacks?

Basement apartmentGarden suite

Either could work.

Answer a few questions to see which way it leans.

0 of 4 answered

The short version.

CostBasement wins
Usually much cheaper.
SpeedBasement wins
Less new construction.
PrivacyGarden suite wins
Separate building.

Compare the things that actually matter.

These are planning ranges. Your property may be easier or harder than average.

FactorBasement apartmentGarden suite

What it isA self-contained unit inside your existing basementA separate, detached building in the backyard

Typical all-in cost (2026)$80,000–$175,000$200,000–$300,000+

Typical timeline, design to occupancyRoughly 3–5 monthsRoughly 6–12 months

Zoning pathUsually as-of-right on most urban residential lotsUsually as-of-right, but some municipalities still route these through older bylaws. Property-specific check needed.

ServicingUses the house’s existing water, sewer and hydro connectionsNeeds its own connections, often trenched across the yard. The main reason it costs more.

Shares a wall?Yes, with the rest of the houseNo, fully standalone

FoundationAlready existsBuilt new

Approval complexityGenerally more straightforwardMore documentation: site plan, servicing, sometimes an arborist report

For what actually moves your number, see Cost & Financing, or get a property-specific estimate from the Cost Calculator.

It comes down to what’s already there.

Cost

Reuse versus start from bare ground.

A basement apartment reuses almost everything expensive about a house: the foundation, the roof, the water and sewer lines. A garden suite starts from bare ground and needs its own foundation and its own utility connections, trenched from the house or the street. That servicing work alone commonly adds tens of thousands of dollars before a wall goes up.

Timeline

Indoors versus exposed to the season.

A basement conversion happens inside a structure that’s already standing, largely unaffected by weather. A garden suite is a small new-construction project (excavation, foundation, framing, servicing) exposed to whatever season you happen to be building in.

Basement already has

Foundation
Roof
Exterior walls
Nearby utilities

Garden suite needs

Foundation
Full exterior shell
Utility trenching
More site work

Cost versus privacy.

Basement apartment

Spend less. Share more.

CostLower

PrivacyModerate

Best when budget and speed matter most.

Garden suite

Spend more. Separate more.

CostHigher

PrivacyHigh

Best when privacy and a fully separate unit matter most.

Look at your property, budget and goal.

Choose a basement apartment if

You want the lowest cost and the fastest path to rent coming in.
Your basement already has reasonable ceiling height and can fit an egress window.
You’re comfortable sharing a building with your tenant or family member.

Choose a garden suite if

You want a fully private, standalone unit with no shared walls or entrance.
Your backyard has the space and setbacks to fit one.
You have the budget and timeline for new construction, and want the higher rent.

Not sure which applies to your lot? That’s exactly what a feasibility check answers, before you spend anything on drawings.