Almost every legal basement apartment conversation we have in Scarborough eventually lands on the same question: “does my house even have room for a separate entrance?” It’s usually the first real obstacle homeowners hit once they’ve decided to move forward with a basement apartment, because unlike interior work, a side entrance addition changes the outside of the house — foundation, grading, and sometimes the property line itself.
Here’s what actually goes into adding one, what it costs, and where it tends to get complicated.
Why a Side Entrance Matters So Much for Legal Basement Apartments
Under Ontario Building Code requirements for a secondary suite, a legal basement apartment generally needs its own dedicated entrance, separate from the main house entry. This isn’t a preference — it’s one of the core requirements that separates a “finished basement” from a legally rentable unit, alongside egress windows and fire separation. Without it, the space can be finished beautifully and still not qualify as a legal second suite.
For Scarborough homes specifically, this usually means one of two approaches: cutting a new entry point into an existing foundation wall with a descending stairwell, or working with a walk-out grade change where the lot’s slope allows it.
What a Side Entrance Addition Actually Involves
Foundation cutting. For homes without an existing basement-level opening, a section of the foundation wall needs to be cut to create the doorway opening — a structural process that typically requires a lintel or beam to support the load above the new opening.
Excavation and stairwell construction. A concrete or block stairwell (sometimes called an area well) is built leading down from grade level to the new basement door, complete with proper drainage to prevent water pooling at the base.
Drainage and waterproofing. This is where a lot of DIY-adjacent side entrance projects go wrong. Without a floor drain at the base of the stairwell and proper weeping tile connection, every heavy rain becomes a flooding risk right at your new basement entry point.
Door and threshold installation. A properly insulated, code-compliant exterior door, sealed and flashed correctly against the new opening.
Surface finishing. The area around the new entrance — whether interlocking pavers, concrete, or a simple gravel path — needs to tie in with the surrounding grade and existing landscaping. This is exactly why side entrance work and interlocking so often happen as one combined project.
What Side Entrance Addition Costs in Scarborough
| Scope | Typical Cost |
|---|---|
| Foundation cutting & structural support | $3,000 – $6,000 |
| Stairwell excavation & construction | $4,000 – $8,000 |
| Drainage & waterproofing at entry point | $1,500 – $3,500 |
| Door, frame & finishing | $1,500 – $3,000 |
| Interlocking/walkway tie-in | $2,000 – $5,000 |
| Total typical range | $8,000 – $18,000 |
Costs shift significantly based on foundation depth, whether structural engineering drawings are needed for the opening, and how much excavation the stairwell requires. Homes on a slope with natural grade change toward the basement level are often cheaper to work with than flat lots requiring a full dug-out stairwell.
Permits and What the City Actually Requires
A side entrance addition tied to a legal basement apartment requires a building permit in Scarborough and Toronto — this isn’t optional. The permit process typically covers structural review of the foundation opening, drainage plan approval, and confirmation that the stairwell and door meet code for egress and safety.
If the entrance is being added purely for convenience (not part of a legal secondary suite), the permit requirements are somewhat simpler, but structural changes to a foundation wall still generally require sign-off given the load-bearing implications.
Where Side Entrance Projects Commonly Run Into Problems
Skipping engineering review on the foundation cut. Removing a section of load-bearing foundation wall without proper structural support risks settling or cracking elsewhere in the house — this is not a place to cut corners on drawings or inspection.
Underestimating drainage needs. A stairwell without adequate drainage becomes a water collection point during Scarborough’s spring thaw and heavy summer storms, which can send water directly into your new basement entry.
Not coordinating with existing landscaping and grading. A new side entrance changes how water flows across your property. Without accounting for existing grading, you can inadvertently redirect water toward your foundation instead of away from it — the opposite of what you want.
Does Every Basement Apartment Need a Brand New Entrance?
Not always. Some Scarborough homes already have a side or rear basement-level door that just needs upgrading — better drainage, a compliant door, and a maintained stairwell — rather than a full new opening cut into the foundation. It’s worth having this assessed before assuming you need the full addition; it’s a meaningfully different cost and scope.
Why Toronto & Scarborough Homeowners Choose SM Builders inc
Side entrance additions sit right at the intersection of foundation work, drainage, and permits — get any one piece wrong and it shows up as a water problem or a failed inspection later. We handle the full scope in-house: structural assessment, permit drawings, excavation, waterproofing, and the finished walkway tying it all together. This work often pairs directly with a basement apartment renovation, and we coordinate both as one project rather than treating them separately.
Considering a side entrance for your Scarborough basement apartment? Request your free estimate and we’ll assess whether your property needs a full new entrance or just an upgrade to an existing one. Call 647 331 7366 or email smbuildersto@gmail.com.
Frequently Asked Questions
How much does a side entrance addition cost in Scarborough? Most side entrance additions, including foundation cutting, stairwell construction, drainage, and finishing, range from $8,000 to $18,000 depending on foundation depth and site conditions.
Do I need a permit for a side entrance addition? Yes, particularly when it’s part of a legal basement apartment. The permit process covers structural review of the foundation opening and confirms the drainage and stairwell meet building code.
Can I add a basement apartment without a separate side entrance? Generally no, if the goal is a fully legal secondary suite. Ontario Building Code requirements for secondary suites typically call for a dedicated entrance separate from the main house entry.
SM Builders builds entrances through our side entrance and interlocking services, and most projects pair with a legal basement apartment renovation — see how the full conversion works.
