
The way in
Separate entrance
A new exterior door cut into the foundation, with the stairwell, guard and drainage designed so the opening does not weaken the wall.
- Foundation opening design
- Stairwell & drainage
- Guards & lighting
- Frost & waterproofing
Legal Basements · Oakville, Halton Region
Legal basement apartments in Oakville, designed, permitted and built by one team: the separate entrance, fire separation, egress windows and heating for two units. We draw the unit to section 4.1.2 of Zoning By-law 2014-014, or to By-law 2009-189 between Dundas and Highway 407, and file it with the Town of Oakville Building Department through ePlan.

What’s included
A legal unit is a list of code items, and the inspector checks each one. We design to that list, build to it, and book the inspections in the order the city wants them. In Oakville the package goes to the Town of Oakville Building Department, and it is drawn to that department’s checklist.
The package
Find your situation below. If it’s there, this is the service, and the card underneath is everything you get from our one office.
06 common situations
07
items in your package, all from one P.Eng and BCIN team.
Drawn & stamped in-house
How it runs
Four steps from a bare basement to a closed permit, with the inspections built into the schedule.
We measure the ceiling, look at the windows, the entrance options and the mechanical room, and tell you whether the basement can be made legal and what it will take.
Layout, separations, the structural opening and HVAC are drawn in one office and filed with the municipality. City comments are answered at no extra charge.
Entrance, framing, rough-ins, insulation and rated assemblies go in, inspected at each stage.
Kitchen, bathroom, flooring and doors, then the final inspection and the closed permit.
Case files
Open any file for the scope, the disciplines involved, what we delivered and what the owner came away with.

A compact two-storey suite in a Toronto backyard. Architectural and structural drawings, zoning review and a framing package that makes every square foot count.
Delivered
New living space on a lot the owners already had.
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Structural walls came out and rooms were added to open the plan. Beam and column design, permit drawings and renovation coordination through to final inspection.
Delivered
An open layout where the load-bearing walls used to be.
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A code-compliant second unit with its own entrance, fire separations between the units, HVAC design and the full permit package.
Delivered
A legal second unit that brings in rent and adds property value.
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A new build taken from the client’s sketch to occupancy, with the architectural, structural and mechanical design done by one team.
Delivered
Built to the client’s own plan, with one team answering for every discipline.
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A two-storey garden suite laid out to get the most usable space from the footprint, designed and permitted as a rentable unit.
Delivered
Rental income and a higher property value.
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A dental office converted into a supermarket. Interior renovation, a new plumbing system and fire separations upgraded to the Ontario Fire Code.
Delivered
A dental office reopened as a supermarket, compliant with the Ontario Fire Code.
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A custom covered porch that turns the front of the house into usable outdoor space. Addition design and structural drawings for the permit.
Delivered
More usable outdoor space and added home value.
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Site grading to manage drainage and prepare the land for a new driveway, drawn as a grading plan for the site alteration permit.
Delivered
Drainage handled and the land ready for a new driveway.
Start a project like thisPhoto plates
Additions, basements, kitchens, new builds and commercial fit-outs. Drag a row to scrub through it, or open any photo full size.Tap any photo to see it full size.
21 platesResidential, commercial & new build
The drawing set
Framing schedules, wall assemblies, dimensions and a city review stamp, as issued. Client title blocks are trimmed off to protect the people we drew them for.
Drawing set
Sheets in this set
Sheet title
Existing basement plan
The existing house recorded before any design: beams, joists and bearing walls.
Drawing no.
2 of 5
Service area
From the office we cover the whole GTA, north to Barrie and Orillia, east to Peterborough and Cobourg, west to Kitchener and Brantford, and down through Niagara.
46 across 8 regions
York Region
Toronto & Peel
Halton
Durham
Simcoe & Dufferin
Waterloo, Wellington & Brant
Hamilton, Niagara & Haldimand
Kawarthas & Northumberland
Past the 90-minute line
We've also completed projects in London and Strathroy. Farther out than that? Call (416) 990-9179 and ask.
Permits filed with municipalities including
Before you call
Anything we haven’t answered here, we’ll answer on a call. The first consultation is free.
(416) 990-9179A building permit for the unit, applied for with drawings at Oakville’s own building department rather than Halton Region. Oakville also has a site alteration by-law, and we check it whenever the stairwell for a new entrance changes the grade beside the house. We prepare and file the set and deal with the examiner’s comments.
Only where the lot is inside Conservation Halton regulation, near a watercourse, a valley or a floodplain. Digging a stairwell down to the basement changes the grade there, and the Conservation Halton permit may be needed before Oakville issues the building permit. On a lakefront lot the shoreline is regulated too where it is at risk of flooding or erosion, so we check the mapping there even with no creek nearby.
Under Oakville’s Zoning By-law 2014-014, attached additional residential units are permitted in detached, semi-detached, linked and townhouse dwellings, and detached additional residential units are permitted in an accessory building associated with those dwellings. A property may have a maximum of two attached additional residential units, or one attached unit and one detached unit. A basement apartment counts as one of those units, and it still needs a building permit of its own.
Yes. We take on legal basements across Oakville, including Old Oakville and Bronte, within an hour of our Richmond Hill office. The first consultation is free, by phone or on site.
Three things to start: property address; basement ceiling height, measured floor to joist; and photos of the basement, the mechanical room and the outside wall where an entrance could go. Send those and we tell you what the Town of Oakville Building Department will ask for before we quote.
That depends on where the lot sits against Dundas Street. South of Dundas, and north of Highway 407, it is Zoning By-law 2014-014, whose section 4.1.2 holds the additional unit rules we draw to; between Dundas and the highway, including most of the 2000s neighbourhoods north of Dundas, it is Zoning By-law 2009-189, and we read that by-law’s own provisions for your address. The Town of Oakville Building Department then checks the unit against the same by-law.
It may. Under O. Reg. 299/19 an additional unit needs one parking space, and a tandem space counts, unless the zoning by-law requires none for the main house or says none is to be provided for the unit. We read the parking rules in Zoning By-law 2014-014 or 2009-189, whichever covers your lot, and show the space on the site plan the Town of Oakville Building Department reviews.
It can. Digging a stairwell cuts roots, and Oakville’s Private Tree Protection By-law 2017-038 needs a permit before a private tree 15 cm or more across at breast height is injured, and the same goes for any tree an approved site plan requires. We plot those trees from the survey and put the entrance where it misses them; if no side does, we apply for the tree permit while the Town of Oakville Building Department reviews the unit.
Possibly, and where it goes is the first question. Old Oakville is one of the Town’s four heritage conservation districts, with First and Second Street, Trafalgar Road and Downtown Oakville, and a stairwell changes the outside of the house, so we look at a side or rear entrance before the front and confirm with the Town what the district asks. With the entrance settled, the rest of the unit goes to the Town of Oakville Building Department.
Through the Town’s Online Services, with the drawings reviewed in ePlan, which runs on ProjectDox. Whoever applies can sign in with a Town of Oakville account and follow the file’s tasks and status, and we answer each round of comments on the fire separation, exits or headroom in the same place until the Town of Oakville Building Department issues the permit.
Yes, and before the offer is firm is the time to do it. We check whether the lot falls under Zoning By-law 2014-014 or 2009-189 and whether Conservation Halton’s regulated area reaches it, then measure the basement’s floor-to-joist height and look for a side of the house where a stairwell could go. Our director is a real estate broker, so the findings come with a view on what a permitted unit would mean for the price.
Searched & answered
Short answers to the legal basements questions people search most, and the broader topics they lead to.
Not covered here? Book a free consultationA legal basement is a basement apartment that meets the Building Code and the local zoning: a self-contained second unit with its own kitchen and bathroom. The code calls it a secondary suite, and Ontario’s planning rules call it an additional residential unit. Fine Engineering designs and permits these units across the GTA and coordinates the build.
At least 1.95 m, about 6 ft 5 in, under Ontario’s 2024 Building Code, with 1.85 m of clear height allowed under beams and ducts. The measurement runs from the finished floor to the finished ceiling, so new flooring and drywall count against it. Fine Engineering measures the height at the first site visit, before any layout is drawn.
It needs a safe way out, which is usually its own exterior door. In a house that has stood for five years or more, the 2024 Building Code’s renovation rules also accept an exit route through the other unit, as long as the suite gets an extra escape window that opens from inside without tools and the smoke alarms are linked. Fine Engineering works out which route suits the layout.
Yes. Once a house has a secondary suite, its smoke alarms must be interconnected, by wire or wirelessly, so one sets off the rest, and shared spaces need them too. A suite with a fuel-burning appliance, or one sharing a wall, floor or ceiling with such an appliance or a garage, also needs carbon monoxide alarms by its bedrooms. Fine Engineering marks every alarm on the permit set.
For many homeowners, yes. A legal second unit can earn rent and add property value, and because it was built under a permit, it avoids the trouble an unpermitted suite causes when the house is sold. The return depends on how much the basement needs, whether that is more headroom, a new exit or fire separation. Fine Engineering prices that work before any drawing starts.
Usually because the heat reaching the room does not match the heat it loses. A room over a garage, or one with more glass and outside wall, loses heat faster, and a long or undersized duct delivers less air than the room needs. A room-by-room heat-loss calculation and a duct design show where the gap is. Fine Engineering does both for existing houses as well as new ones.
Good to know
In Oakville the reviewer is the Town of Oakville Building Department. Every Oakville lot sets its own terms: the spare capacity in the electrical panel and the size of the water service the two units will share decide how much work a basement unit needs.
We walk the site with the survey on a scheduled visit before anything is drawn, then file the legal basements package to the Town of Oakville Building Department’s own checklist.
Oakville’s housing runs to lakefront and older Oakville lots being rebuilt, 1980s Glen Abbey subdivisions and 2000s neighbourhoods north of Dundas. On a lot being rebuilt, a basement unit is easiest planned before the foundation goes in, with ceiling height and drain depth set on the drawings. In an existing house in Kerr Village or Glen Abbey, floor-to-joist height decides whether underpinning is needed.
Once a house has stood for five years, the Building Code’s renovation rules accept a 30-minute fire separation around a second unit, and an exit through the other unit if an extra escape window is added. Basements in the 1980s Glen Abbey subdivisions and in the 2000s houses north of Dundas qualify on age.
The exception in Oakville is the rebuilt lot. A replacement house on a lakefront or older street can be under five years old, and then its basement unit follows the rules for new construction. We note the year the house was finished on the first site visit, and the separation and exits we draw for the Town of Oakville Building Department follow from it.
Section 4.1.2 of Zoning By-law 2014-014 gives an Oakville property two patterns: two attached units in the house, or one in the house and one in an accessory building such as a garden suite. A second unit in the house uses up the allowance, and a suite could no longer follow.
If a suite is a possibility, we draw the basement as the only unit in the house, keep a side yard open for the service route to the back, and check the rear yard against Oakville’s tree by-law early. Our broker can talk through which arrangement suits the property before either is drawn.
Contact us
Send us the ceiling height and a few photos and we’ll tell you whether the basement can be made legal, on a free first call.
First consultation free(416) 990-9179