Basement & Secondary Unit
Permit Drawings in Ontario
Permit-ready drawing packages for legal basement apartments and secondary suites. We prepare coordinated architectural + structural drawings and coordinate required supporting documents when needed.
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Basement Secondary Unit Permits: Clear, Review-Ready Drawing Packages
A legal basement apartment, secondary suite, or second dwelling unit usually needs more than a simple floor plan. Permit review focuses on life-safety items and clear documentation — and delays often happen when details are missing, unclear, or inconsistent.
We prepare the submission documents for your basement permit package, including architectural drawings, structural engineering, and coordinated supporting documents when required for the scope. This can include mechanical/HVAC, plumbing layouts, electrical coordination, fire separation notes, egress information, and other details the municipality may ask to review.
If your project requires structural work, such as new openings, enlarged windows, a separate entrance, underpinning scope, or beam/post changes, we include engineered details so the drawings match the real structure behind the walls.
What We Provide
Permit-Ready Drawings
Basement floor plans, sections, construction notes, and details prepared for municipal building permit submission.
Secondary Unit Layout Review
Clear review of the proposed suite layout, including bedrooms, exits, windows, stairs, ceiling heights, and service areas.
Structural Engineering Support
Structural details for new openings, beams, posts, lowered slabs, underpinning review, or other changes when required.
What We Provide for Basement & Secondary Unit Permits
Basement permit applications often involve several small details that can slow down approval if they are not shown clearly. We prepare a coordinated drawing package that explains the proposed work, identifies code-related items, and gives your contractor a clearer path before construction starts.
- Basement permit drawings for finished basements, basement apartments, and legal secondary units
- Existing basement layout review, including room use, stairs, exits, windows, and ceiling height conditions
- Floor plans, construction notes, wall assemblies, fire separation notes, and permit-ready details
- Structural drawings for beams, posts, wall openings, foundation changes, or slab lowering where required
- Coordination notes for mechanical, HVAC, plumbing, and electrical documents when they apply
- Revisions and clarification responses if the municipality requests changes during permit review
If your basement project includes removing walls, enlarging windows, creating a separate entrance, adding bedrooms, or changing the structure, it is better to confirm the permit scope early so the drawings match what the City expects.
Common Items Reviewed for Basement & Secondary Unit Permits
A legal basement apartment is not just about adding a kitchen and bedroom. The space has to be safe, accessible, and properly separated from the rest of the home. We help document these items clearly so your permit submission is easier to understand.
Layout, Egress, and Fire Separation
Secondary unit drawings often need to show bedroom windows, exits, stairs, fire-rated separation, smoke/CO alarm locations, and the relationship between the basement unit and the main dwelling.
- Bedrooms, exits, windows, and stair layout
- Fire separation and safety notes
Structural and Service Coordination
Some basements need more than layout drawings. Enlarged window openings, lowered floors, new beams, separate entrances, plumbing changes, and HVAC changes may need coordinated engineering details.
- Beams, lintels, posts, and openings
- HVAC, plumbing, and electrical coordination
How a Basement Suite Permit Package Comes Together
A basement unit is judged on life safety before anything else. We work through the requirements in the order that decides whether the layout is viable at all.
1. Feasibility Check
Before design begins we confirm the things that can stop a project: available ceiling height, where an exit can realistically go, whether existing windows can become egress windows, and where mechanical equipment sits.
2. Existing Conditions Documented
We record the existing basement accurately — beam and post locations, duct runs, floor drains, window sizes and sill heights, and the framing above. These details drive the layout more than preference does.
3. Code-Compliant Layout Design
The unit is laid out around fire separation, sound separation, egress, ceiling height and ventilation requirements, rather than drawing a floor plan first and forcing compliance afterwards.
4. Submission and Review Support
We prepare the package to your municipality’s second unit checklist and respond to review comments through to permit issuance.
What Shapes a Basement Apartment Scope
These are the conditions that most often decide how involved a basement suite project becomes.
Ceiling Height
Ceiling height is the single most common obstacle. Where the existing height falls short, underpinning or bench footing becomes part of the project, which adds structural design and a significant construction component.
Egress Windows and Window Wells
Bedrooms need an egress opening meeting minimum size requirements. Existing basement windows are frequently too small, which means enlarging the opening, a new lintel, and often an excavated window well with proper drainage.
Separate Entrance or Walkout
A side entrance or basement walkout affects grading, foundation work, stair design, guards and drainage. It is often the largest structural element of a basement suite project.
Fire Separation and Sound Rating
Assemblies between units need a defined fire-resistance rating and sound transmission rating. This drives ceiling and wall build-ups, door ratings, and how ducts and services penetrate the separation.
Ventilation and Heating
A self-contained unit needs its own ventilation provision and adequate heating. Whether the existing system can serve two units, or whether separation is required, affects both the drawings and the mechanical work.
Zoning and Additional Residential Units
Zoning governs whether a second unit is permitted, along with parking, entrance location and unit size. We confirm these before design so the layout matches what your by-law actually allows.
Who We Work With
We work with homeowners creating a legal basement suite, investors adding an additional residential unit, and contractors who need a second unit package that clears review the first time.
Homeowners
We help homeowners turn unfinished basements, family spaces, and rental suite ideas into clear, permit-ready drawing packages.
Property Owners
We support owners improving rental properties, investment homes, and long-term family homes with organized basement permit documents.
Contractors & Builders
We prepare accurate plans and engineering notes that reduce back-and-forth, support inspections, and help basement projects stay buildable on site.
Our Services
From residential renovations to commercial permits, we provide P.Eng-stamped structural drawings and coordinated engineering support across the GTA.
Why our clients keep coming back.
All drawings stamped and certified by Professional Engineers of Ontario.
Over 30 years of experience in all categories of construction projects, from residential to commercial.
We know GTA municipalities well — that means faster reviews and fewer back-and-forth cycles.
Professional engineering services at competitive, transparent rates.
You’ll always know where things stand — we keep you updated throughout.
Every municipality has its own quirks. We know them so you don’t have to learn the hard way.
Additional Coordinated Services
We coordinate supporting documents when they apply to your permit scope.
If your open-concept project is part of a larger renovation that requires additional documents, we can coordinate them so the package stays consistent.
Where We Work
We prepare basement apartment and secondary unit permit drawings across the Greater Toronto Area and Durham Region, including Whitby, Oshawa, Ajax, Pickering, Toronto, Markham, Vaughan, Newmarket and Kawartha Lakes. Second unit requirements and parking rules differ between municipalities, so we confirm your local by-law before design begins.
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Partner with us for structured permits, seamless approvals, and engineering built to last. Tell us about your project and we’ll walk you through exactly what your municipality needs.Request a Quote
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Basement & Secondary Unit Permit FAQs
Do I need a building permit for a basement apartment in Ontario?
Yes. Creating a legal basement apartment or secondary suite requires a building permit. The permit confirms the unit meets Ontario Building Code requirements for fire separation, sound transmission, ceiling height, egress windows, exits, smoke and carbon monoxide alarms, ventilation and heating. Finishing a basement without creating a separate dwelling unit still usually requires a permit when framing, plumbing or electrical work is involved.
What drawings are needed for a basement secondary unit permit?
A typical submission includes existing and proposed basement floor plans, a site plan, fire separation and sound transmission details, egress window and exit details, mechanical and ventilation information, and structural details for any new openings, beams or underpinning. We prepare the coordinated package and identify anything your municipality asks for beyond the standard checklist.
What is the difference between a basement apartment and a secondary unit?
In practice they describe the same thing: a self-contained dwelling unit with its own kitchen, bathroom and sleeping area within an existing house. “Secondary unit” or “additional residential unit” is the language most Ontario zoning by-laws use. The distinction that matters for your permit is whether the unit is self-contained, because that determines which Building Code requirements apply.
Do I need a separate entrance or a basement walkout?
A second unit needs a means of egress that meets the Building Code. That can sometimes be achieved through a shared entrance with the right fire separation, and in other cases a separate side entrance or a basement walkout is the practical solution. We assess your existing layout and design the option that works for your house, including the structural details and grading a walkout requires.
What fire separation and sound requirements apply between units?
The Building Code requires a fire separation between dwelling units, typically with a defined fire-resistance rating, along with a sound transmission rating between units. This affects ceiling and wall assemblies, door ratings, service penetrations and duct treatment. Our drawings specify the assemblies clearly so your contractor builds what the inspector expects to see.
What egress and window requirements apply to basement bedrooms?
Every basement bedroom needs an egress window or door meeting minimum opening size and accessibility requirements, and it must open without tools or special knowledge. Existing basement windows are often undersized, which means an enlarged opening and a new lintel. We design the structural opening and detail the window well where one is needed.
Do I need a permit for basement underpinning or lowering the floor?
Yes. Underpinning or bench footing to gain ceiling height is structural work affecting your foundation, and it requires engineered drawings and a permit. We design the sequence, depths and details, and provide the stamped drawings your municipality and contractor need.
How do I start a basement permit drawing package?
Call us or fill in the quote form on this page with your address, a description of the basement layout you have in mind, and any existing drawings or photos. We review it and come back with a free, no-obligation quote and a clear outline of what your city will require. The initial review costs you nothing.