"Can you just design it, or do I need to hire an architect too?" We hear a version of that question on almost every new cottage or house project. The honest answer is that Ontario law draws the line in a specific, checkable place — it is not a matter of preference or project size alone. Here is how the rule actually works, where a BCIN-registered designer can legally take your project from concept to permit, and where the law requires you to bring in a licensed architect or a professional engineer instead.
Two Separate Legal Frameworks, Not One
People often assume "BCIN" and "architect" are competing options for the same job. They are not quite that. Two different pieces of Ontario legislation are doing two different things:
The Building Code Act requires that anyone who prepares the drawings submitted with a building permit application — and who is not an architect or a licensed engineer — be registered with the Ministry of Municipal Affairs and Housing and hold the applicable BCIN qualification for the scope of work. BCIN stands for Building Code Identification Number, and registration is broken into classes such as House, Small Buildings, Large Buildings, and Complex Buildings, plus specialty categories like Building Structural and On-Site Sewage Systems. Separately, the Architects Act and the Professional Engineers Act restrict who may practise architecture or professional engineering at all. For certain building types and sizes, the law does not let a BCIN designer do the design work regardless of registration — only a licensed architect, a Professional Engineers Ontario (PEO) licensee, or both, may take it on.
A BCIN designer working within their registered class is not a discount substitute for an architect. They are following a different, equally legitimate legal pathway — one that Ontario built specifically for houses and small buildings. The question is which pathway your project falls into.
When a BCIN-Registered Designer Can Legally Handle Your Project
The Ontario Association of Architects and Professional Engineers Ontario publish a joint bulletin, issued under Section 11 of the Architects Act and Section 12 of the Professional Engineers Act, that sets out exactly which buildings require an architect, a PEO licensee, or both. Read the other way around, that table also tells you when a BCIN designer is legally sufficient.
For most single-family cottages and homes, the answer is straightforward. A residential building of three storeys or fewer that does not exceed 600 square metres does not trigger the architect/PEO requirement under that bulletin, regardless of how its dwelling units are arranged. That is the space a BCIN "House" or "Small Buildings" registration is designed to cover — which is also why a BCIN designer can prepare your permit set for the great majority of cottage, cottage-addition, and single-family home projects across our service area.
House and Small Buildings are two different registrations, and the line between them is unit count, not layout. Under the Building Code, a "house" means a detached house, semi-detached house, townhouse or row house containing not more than two dwelling units. The test turns on how many units the building holds — not on whether they sit side by side or one above the other, which is a common misconception. A duplex with one unit above the other is still a house. A six-unit townhouse block, every unit side by side, is not. Buildings past that two-unit line — stacked townhouses, low-rise apartments, mixed-use buildings — fall to the Small Buildings class, still inside Part 9's limits of three storeys and 600 square metres in building area. Part 9 itself sets no condition about stacking.
Our own registration follows this framework: BrambleRidge Home Design Group holds both House and Small Buildings qualifications, covering residential and commercial buildings up to 600 square metres (6,458 square feet) in building area and three storeys.
Renovations and additions to an existing house generally stay in this same lane, provided the finished building doesn't cross those size and occupancy thresholds. A three-season-to-four-season conversion, a family addition, a garage, or a new single-family cottage build are the kinds of projects a qualified BCIN designer is legally equipped — and registered — to design and submit for permit.
When Ontario Law Requires an Architect or a Professional Engineer
The same joint bulletin sets out the situations where a BCIN designer legally cannot take the design past a certain point, no matter how experienced they are. For a purely residential building, an architect and a PEO licensee become required once it exceeds three storeys in height; below that, an architect alone becomes required once the building exceeds roughly 600 square metres and either stacks one dwelling unit above another or contains three or more units. Once a project combines residential space with another major occupancy — other than industrial, assembly, or care-or-detention — the trigger becomes simpler: an architect and a PEO licensee are required if the building exceeds 600 square metres or three storeys, full stop. The same size threshold governs business, personal-service and mercantile buildings on their own, which likewise require both professions. Industrial buildings share that threshold but differ on who may take them on: an architect or a PEO licensee, rather than both. Assembly occupancies and care-or-detention occupancies are treated differently again — they require an architect and a PEO licensee at any size, with no small-building exemption.
One threshold catches people out, and it is worth stating plainly: the architect test and the Building Code qualification test do not measure area the same way. Part 9 and a designer's registration are bounded by building area — essentially the footprint. But the architect trigger for a building containing one dwelling unit above another is measured in gross area, the floor area of every storey added together. A three-storey stacked building on a 200-square-metre footprint is only 200 square metres of building area, comfortably inside Part 9, yet 600 square metres of gross area — right at the point an architect becomes required. It is entirely possible to be properly qualified under the Building Code and still need an architect under the Architects Act. Any project with dwelling units above one another is worth checking against both tests before drawings begin.
In practical terms for our region: a full-size lodge, a multi-unit rental building, a larger commercial build, or a resort-style assembly space is very likely to need an architect, an engineer, or both, layered on top of — or instead of — a BCIN designer. That is by design. The legislation reserves the more complex and higher-risk building categories for the professions with the broadest scope of licensed practice, while still leaving room for BCIN-qualified designers to serve the houses and small buildings that make up most of cottage country construction. Exact classification depends on the finished building's use, area, storey count, and unit configuration, so a project near any of these thresholds is worth confirming directly with your designer before drawings begin.
Where the Line Gets Blurry in Practice
A few situations are worth flagging honestly rather than glossing over:
Additions that push a property over a threshold deserve early attention: if an addition, a garage suite, or a multi-unit conversion brings the finished building's area, storey count, or unit count close to the limits above, the project needs to be checked against current thresholds before design starts, not after drawings are underway. Structural design is widely misunderstood. On a house, loadbearing structural design sits inside the House class itself: the Building Code's qualification table carves plumbing, HVAC, building services, sewage systems and detection, lighting and power out of that class, but it does not carve out Building Structural. Beams, columns, footings and foundations for a house — including an unusual condition such as a pier foundation set into exposed Canadian Shield bedrock — are ours to design and size, and an engineered beam in a cottage does not by itself require an engineer's stamp. Some work genuinely does fall outside that scope: a retaining wall over one metre is Building Structural regardless of the house it serves, and on a non-house Small Buildings project the structural work is carved out to that same separate category. Where a project reaches past our registration we bring in a professional engineer — but we do not outsource house framing we are qualified to design. Septic systems are their own track entirely: most cottages here are on private septic rather than municipal sewer, and on-site sewage system design is registered and qualified separately under the Building Code, coordinated by your designer but not covered by a house-class registration alone. And none of the above replaces your municipality's own building permit review, or a conservation authority's review where one has jurisdiction over your shoreline or floodplain — those approvals run alongside the designer-qualification rules, not instead of them.
Because thresholds, classifications, and how a specific project gets categorized can be genuinely project-specific, this is an area to confirm directly rather than assume — with your BCIN designer at the outset, and with the Ontario Association of Architects or Professional Engineers Ontario for anything close to the size or occupancy limits above.
How to Check Before You Hire Anyone
You do not have to take a designer's word for their qualifications. The Ministry of Municipal Affairs and Housing maintains a public registry — commonly referred to as QuARTS — where you can confirm a designer's BCIN number, their firm registration, and the specific qualification categories they hold, before a contract is signed. The Ontario Association of Architects likewise maintains a public register of licensed architects and certificates of practice. Five minutes with either registry is a reasonable step for any project, and a legally required one for anyone who is not sure whether their project falls on the BCIN side of the line or the architect side.
Bringing the Right Professional to Your Project
For the overwhelming majority of cottages, cottage additions, and single-family homes we see from French River to Orillia, a BCIN-registered designer is exactly the right — and legally correct — professional for the job, and working with one locally means someone who already knows the Canadian Shield terrain, the seasonal-access challenges, and the building departments across Parry Sound District, Muskoka, Haliburton, and Simcoe North. If your project is larger, denser, or falls into an occupancy category that the law reserves for architects and engineers, an honest designer will tell you that up front and help you find the right professional rather than take on work outside their registration.
If you're planning a cottage, a renovation, or a new build anywhere in our cottage-country service area and aren't sure which side of that line your project falls on, reach out to BrambleRidge Home Design Group. We'll tell you plainly whether a BCIN designer can carry your project through design and permit, or whether it needs an architect or engineer alongside us, before you spend a dollar on drawings.
