What Is a Basement Suite? Alberta and BC, Explained

Across Alberta and British Columbia, the below-grade rental unit is a “basement suite.” It’s the most common form of secondary housing in both provinces, and an enormous number of them were built without permits.

The useful thing about basement suites is that legality is genuinely checkable. Unlike zoning questions, which depend on your lot, the code requirements are a finite list you can walk through with a tape measure. This guide sets that list out for both provinces.

(If you’re in Ontario or the GTA, the term there is “basement apartment” and the rules differ — see our Ontario guide instead.)

What is a basement suite?

A basement suite is a self-contained dwelling unit in the below-grade level of a house, occupied independently of the main home.

The City of Calgary defines a secondary suite as “a self-contained residence with two or more rooms” including “a kitchen, living, sleeping and sanitary facilities.” All suites must have bedrooms with proper egress windows, a separate bathroom, separate cooking facilities, and an entrance accessible from outside without passing through the main dwelling — a shared stairwell is acceptable, provided each unit has its own private entrance.

That shared-stairwell allowance matters more than it sounds. Many homeowners assume they need a separate exterior door cut into the foundation. A common indoor landing that both units open onto can satisfy the requirement, which is often a considerably cheaper solution.

What makes a basement suite legal in Alberta and BC

Both provinces work from the same code family with meaningful differences. Here’s the checklist.

Ceiling height

Alberta. Under the National Building Code – Alberta Edition, ceiling height within a secondary suite and above stairs must be at least 1.95 m (about 6’4¾”). Ceilings may be reduced below ductwork and beams to 1.85 m.

British Columbia. Ceilings, and the undersides of beams in passageways, must be at least 2 m above the floor.

This is the requirement that most often kills a project outright, because it’s the hardest to fix. Gaining height means underpinning the foundation or lowering the floor slab — structural work with structural cost. Measure before you plan anything else.

Egress windows

Both provinces require essentially the same standard for bedrooms: an unobstructed openable area of at least 0.35 m² (3.77 sq ft), with no dimension less than 380 mm (15 inches).

The window must be openable from inside without keys, tools or special knowledge, and without removing sashes or hardware. In BC, the sill height is limited to 1 m above the floor and 7 m above adjacent ground level.

Note that 0.35 m² with a 380 mm minimum dimension is not one shape — a tall narrow window and a short wide one can both fail. Both dimensions and the total area have to work.

Fire separation

Alberta. A smoke-tight separation is required between the main residence and the suite, and in common spaces and the furnace room. Doors in common spaces, the furnace room, or between dwellings must be solid core wood at least 45 mm thick with a self-closing device.

British Columbia. Dwelling units and common spaces must be separated by a fire separation acting as a continuous barrier to smoke and fire. The rating required is 45 minutes — reduced to 30 minutes where additional photo-electric smoke alarms are installed in each unit and interconnected. A fully sprinklered house is treated differently.

That BC trade-off is worth knowing: adding interconnected photo-electric alarms can reduce the required fire-resistance rating, which can be considerably cheaper than building to the higher rating.

Smoke and carbon monoxide alarms

Both provinces require hardwired, interconnected smoke alarms — meaning when one sounds, they all sound — plus carbon monoxide alarms. Interconnection across both units is the norm.

Separate entrance, plumbing and electrical

A private entrance per the definition above. Plumbing and electrical work requires its own permits and, in most cases, licensed trades. A second kitchen frequently means an electrical service upgrade.

One BC point worth correcting

The BC Building Code formerly capped a secondary suite at 90 m² of finished living area or 40% of the building’s total living floor space, under section 9.36.1.1. That restriction was removed — reported as taking effect in December 2019 — giving homeowners considerably more flexibility on suite size.

The old figures are still quoted constantly on builder and realtor sites. If you’ve been designing around a 90 m² ceiling, check the current provisions before you shrink your plan.

Calgary vs Edmonton vs BC

The code is provincial; the process is municipal.

Calgary. Requires a building permit, with a development permit in some circumstances, plus separate electrical and plumbing permits. The City runs a Secondary Suite Incentive Program — up to $10,000 for safety elements, currently waitlisted since 24 June 2026, and applicable only to suites within the main dwelling. Calgary also applies an Airport Vicinity Protection Area overlay in parts of the city, which can restrict new residential units — worth checking your address against.

Calgary is also mid-change on zoning: Council approved a repeal of blanket rezoning on 8 April 2026, taking effect 4 August 2026, while separately moving to list secondary suites and backyard suites as permitted uses in low-density residential districts. Our Calgary building guide tracks the current position.

Edmonton. Secondary suites are governed by Zoning Bylaw 20001, with the Small Scale Residential zone permitting several units on a standard lot. Edmonton does not currently list a municipal suite grant. Our Edmonton building guide covers the process.

British Columbia. Permission is now unusually broad — the Province of British Columbia’s SSMUH rules require most municipalities to permit three to four units on residential lots, rising to six near frequent transit, and secondary suites are permitted province-wide in single-family residential zones. Municipal registration processes and fees differ — Surrey, for instance, applies secondary suite utility and service fees to annual property taxes once a suite is registered.

On grants, be accurate: BC’s $40,000 Secondary Suite Incentive Program closed to new applications after 30 March 2025, and the federal $80,000 loan was cancelled. Neither is available.

What it costs to build

We don’t publish a figure — the range between a basement that already has height and drainage and one needing underpinning is too wide for a single number to be useful.

The cost drivers, roughly in order:

• Ceiling height. If you’re short of 1.95 m (Alberta) or 2 m (BC), underpinning changes the budget category entirely.
• Egress. Enlarging window openings below grade means cutting concrete and often excavating a window well.
• The separate entrance, where a shared stairwell won’t work.
• Fire and sound separation between units.
• Electrical service capacity for a second kitchen, and metering arrangements.
• Provincial cost base. BC charges 7% PST on many construction inputs; Alberta has no provincial sales tax. On a full basement build-out that is a real difference.

What it rents for

Set by your local market, with three honest caveats.

A below-grade suite rents for meaningfully less than an equivalent above-grade unit in the same neighbourhood — natural light, ceiling height and the simple fact of being underground all discount it.

Suite quality matters more below grade than above. A suite with good egress windows, proper sound separation and a private entrance rents materially better than a dark one reached through a shared laundry room.

And any projection that ignores vacancy, maintenance and tax on rental income isn’t a projection.

Is an unregistered suite worth registering?

Usually yes — and the reasons are not the ones people expect.

The common assumption is that the risk of an unpermitted suite is enforcement: a complaint, an order, a fine. That does happen, but it’s not the main argument.

The real arguments:

Insurance. An undisclosed rental unit can compromise a claim. If a fire starts in an unpermitted suite, the position you’re in is considerably worse than the cost of having permitted it.

Mortgage qualification. Lenders generally won’t count rental income from an unpermitted unit toward qualifying you. Since counting that income is often what makes a refinance work, an unregistered suite can be actively costing you borrowing capacity.

Resale. A well-advised buyer will discount for an unpermitted suite or require it be removed as a condition. You pay for it either way, later and on someone else’s terms.

Incentive eligibility. Every suite incentive in Canada pays against legal, registered units.

The honest counterpoint: legalising can be expensive, and occasionally impossible. If your ceiling height is 1.7 m, no amount of paperwork fixes it without underpinning. Get an assessment of what compliance actually requires before deciding — the answer ranges from “a weekend of alarms and a self-closing door” to “structural work.” Both are worth knowing.

Find out whether your basement can carry a legal suite

Ceiling height, egress and servicing decide this, and all three are measurable before you spend anything on design.

HouseLyft’s free property assessment establishes what your property can support and what bringing a suite to code would actually involve. Our secondary suites overview covers the category more broadly. When you want an answer for your own basement, request your free report.