In the guest room, where would the bed go? Do guests need a walk-in? consider a reach-in, and moving the ensuite, to allow for good bed placement, ideally where the headboard and nightstand are not ”right there” when you enter the room.

@bpath For the guest room we definitely wouldn't need a walk-in, but I just mirrored what was above in the master for simplicity.

And oops I sketched in a box to note the egress would be off that wall, but there'd actually be two windows along the wall with space for a bed in the centre. My bad!

I’m not sure what your heating or cooling system will be, but if it needs ductwork, I wouldn’t put it under the garage. A mechanical room surrounded by concrete walls and having a concrete ceiling makes it very difficult to run ducts and even water lines.

@WestCoast Hopeful You're right, it would be a bit of a jaunt from the rec room to the guest bath upstairs if there was someone staying in the basement guest suite. We'll make note of that!

The majority of the back wall will be under a deck, but we are still deciding whether to grade the back yard in such a way that the deck is raised and there are daylight windows in the basement below. For our intended purpose of a home theatre, the light really wouldn't be necessary, but of course future owners using it as a kids playroom would appreciate it.

In my (admittedly limited) experience, the garage slab is usually the one area that doesn't have basement under it. Perhaps due to the weight of cars? Something to ask about since reinforcing the garage floor supports might raise your costs.

You can also have window wells and you may need them for egress from the basement rec room

@WestCoast Hopeful From what I can tell, the National Building Code of Canada only requires egress windows in rooms meant for sleeping, but I'll be sure to confirm before we finalize the plan, thank you!

I think you are right but it will be significantly nicer with natural light

These days, AV equipment doesn't need that much space, and benefits from having air circulation to cool it off. A nice cabinet to hold a receiver or amp/pre-amp would suffice, and if a turntable is part of the system, it should be out in the room to allow easy access.

A wiring closet with router and rack for the house computer system is definitely a plus. But it's unlikely to need as much room as what you have mapped out for AV. How did you calculate the amount of space you need for AV?

@Jennifer K We actually calculated the east-west length we need for the rec room based on the established north-south width & Golden Ratio. There was about 5 ft left over and we just figured it could be used as the wiring closet.

It's definitely bigger than we'd need to be, but this is a pretty broad strokes "general area" type of plan and I can't think of another use for that area. Our design team left it as a blank slate until we have the main floor sorted out, but of course it was there in the PDF so the wheels in our heads started turning...

We did play around with flipping the rec room 90-degrees so the long wall is north-south, but were concerns that the wall the designer indicated was likely needed for support, so at minimum there'd be beams in the middle.

Right off the bat just disregard excavating under a garage. Not an option here. Something with your parent's house is amiss or misunderstood.

There seems to be inconsistency in design of the house, and specifically your basement to this house. Realize your house sits in a "value oriented" genre: a 2BR/2BA; it has a small Great Room and bedrooms; a small basic Master bath; (originally) a 1.5 car garage. So the basement should match the level of the house, yet in contradictory fashion it is probably needed for a 3rd bedroom and Family Room, which would want it to be more open and accessible considered as part of the main floor, not relegated to be designed as leftover space. That dichotomy will fluctuate with your budget.

So given that, the stair could be better oriented to circulate with the main floor. That simultaneously presents an opportunity to be efficient in grouping circulation space upstairs. You may also want to think about having a crawl space over some of it, because if you can even think about affording the extra cost for below-garage excavation or this size of basement for it's genre, then that money should be put into larger upstairs rooms that are more dynamic and/or a luxury Master ensuite. And, if your site allows the opportunity for a look-out basement, the entirety, including upstairs adjacencies and the garage placement (so you don't have to fill or have 7 steps down to it) should be designed with the site in mind. So to illustrate for conversation:

@3onthetree Axing the below-garage excavation thought that flitted through. Not sure what miracles my parents summoned to do theirs. We're with you on placing the mech room under the kitchen instead.

We take your point on the location of the staircase. Once the rec room is finished (down the road, as budget allows), we would love to have it feel like an extension of the main floor living space. We actually specified that we not have the staircase accessed through the mudroom (as we've seen in many other plans) for that exact reason. Having it beside the mudroom doesn't seem much better on paper, but shifting the south wall of the great room back a few feet will at least have it more "around the corner" than "down the hall".

We can't see a way of repositioning it without scrapping the existing layout, though. We're happy enough with the overall plan that we wouldn't want to request a do-over to solve that one issue, but we will ask our design team if they can see a way to shuffle things that we can't.

Appreciate you taking the time to provide a visual aid! That's always really helpful for us.