Or, since there is this alternative in Ontario, a licensed architectural technologist.

Homebuilding in Toronto is a highly bureaucratized and lengthy procedure, much different from most of the US.

No matter where you are, building a custom home is not a DIY job unless you are a licensed architect.

You need an architect and they will help you through the process . It is hard to tell from your question but are you already in the building phase ? Waht kinds of must haves are you asking about?

Years ago a neighbour asked another builder and myself for rough quotes. We were both about the same, they said.

But the husband and wife teachers decided they could diy. And they did. I used to count the obvious errors and unnecessary costs.

Finally, in a moment of unasked for revelation when they were done, the husband confessed that they couldn't believe what builders have to deal with. They were both grey with exhaustion (Sorta the way I feel many days!)

Plant the money tree now. And water it well.

^^^^^^

The realtor's presentation doesn't make the distinction between actual building costs and what a builder will charge the client. For instance, I'm projecting hard and soft costs up to C$400 sf on our current build. But if this were built for a client, the builder would expect to net at least $200K-$250K++ in built-in profit.

The diy who figures they're "saving" that profit underestimates building difficulties while forgetting the income they're foregoing in their own occupation. "Hey, justa bunch of blue collar dummies. I can do that standing on one leg with one eye closed."

must haves to get done while framing:

All incomplete decisions.

Prior to framing, all fixtures, cabinet brand, windows ordered, roof material selected, fireplace ordered, HVAC system ready to order,

In Ontario, at the minimum, check that your builder is registered with the mandatory Home Construction Regulatory Authority (Link), which also mandates TARION warranty enrolment.

But if you want to act as your own builder/contractor for your own use, you're free to do so.

We build custom homes in the GTA, so this question comes up on every project — and the honest answer is that framing is the last cheap moment in the build. Everything on this list costs a few hundred dollars now and a few thousand after drywall.

Verify before the framing goes vertical

• Foundation location survey by an OLS before you frame. It confirms your foundation actually sits where the approved siting says. Setback errors are fixable at this stage and very expensive later.
• Have the surveyor certify height before the roof goes on. Toronto measures height off a defined grade reference, and if the as-built is over, you want to know while you can still adjust the roof rather than after final inspection.
• Window rough openings against the manufacturer's actual RO list, not the drawings.
• Stair rough opening and riser count against finished floor thicknesses. Add up your subfloor, underlay, heated-floor mat, and hardwood or tile on both levels. This is the single most common headroom and code-compliance error we see on Part 9 homes.
• Duct and drain routing laid out before any ceiling is framed. On a 50ft lot with a finished basement, HVAC routing decides where your bulkheads land. Deciding it after framing is how you end up with a bulkhead down the middle of the rec room.

Rough-ins to run while walls are open

• Conduit from the panel to both garage bays for EV charging — confirm what your permit set requires, then run more than the minimum. Two cars, two circuits.
• CAT6 to every TV location and office, plus a ceiling drop on each floor for a WAP, and hardwired camera runs to soffits and corners. Empty conduit to the attic and to the exterior.
• Gas lines: range, BBQ, fireplace, dryer, and a stub for a future generator or pool heater.
• Frost-free hose bibs front, rear, and garage. Exterior GFCI outlets, including one soffit circuit on a switch for holiday lighting.
• Second-floor laundry: recessed pan, drain, and a proper shutoff box. Consider whether the joists need to be dropped for the pan.
• In-floor heat in bathrooms and the basement — at minimum run the conduit and the thermostat box even if you don't buy the mats now.
• Basement bathroom rough-in, and know exactly where your sump and weeping tile connection land before the slab.

Blocking — the cheapest thing you will ever regret skipping

Grab bars in every bathroom (you don't have to install them, just be able to). Wall-hung vanities and wall-mounted toilets. Floating shelves. TV mounts. Heavy mirrors. Shower curtain rods and glass panel anchors. Upper cabinets and range hood. Closet systems. Shower niches framed and benches sloped now, not improvised by the tile setter.

The envelope decisions that get locked at framing

Where the air barrier is and how it transitions at rim joists, wall-to-roof, and the garage-to-house separation. Whether you have continuous exterior insulation — that changes window bucks, strapping depth, and the brick ledge relationship, so it has to be settled before framing, not detailed later. Whether the attic is vented or conditioned. Interior mineral wool around bedrooms, bathrooms, and the mechanical room, and resilient channel under the primary suite. Nobody has ever told me their house was too quiet.

Two more

• If any part of your design is engineer-stamped — beams, LVL, steel, an open web system — the field review letters need to be in your file. Chase them at framing while the engineer can still see the work.
• Photograph every single wall and ceiling before insulation, with a tape or laser in frame for reference. Both floors, every room, including behind where the tubs will go. It costs an hour and it will save you a demolition at some point in the next twenty years.

And to the earlier point about locking product decisions: fully agree, and windows are the one that will actually stop your job. Order them before framing starts.

Happy to answer specifics if you're mid-build.