New construction: Garage with basement below (Toronto)

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Posted by: from Toronto
5/21/2019 at 2:52:28 PM

Summary: Cost to incorporate a full-height (8') basement below an as yet to be constructed garage/laneway suite.

Recent changes to Toronto By-Laws now allow as of right laneway housing, in certain areas and obviously subject to size restrictions etc.. It currently appears that my property qualifies (I'm 99% sure, looking into the remaining 1%). I'm looking at removing an existing 16' x 21' wood framed garage, with very poor (read thin!) concrete slab. Then adding a two-storey 17' x 25' laneway suite, with garage on main floor, and batchelor pad accommodation above.

All that aside, I'm contemplating adding a full basement below the structure. We're already going to be making a huge mess, and won't get a second shot at doing it in my lifetime. So I'm wondering how much this would add to the price? I recognize, it won't be cheap or easy, since a structural floor slab will be required. A significant one at that, as I'd like to add a vehicle lift (stacker) to get a second car in there. There's also slab water proofing and drainage issues etc.. However, it could be a really great project, and I know it can be done, it's just a question of how much.

There is full laneway access, albeit with a 90 bend near the entrance, and ~1M, access down the side of the house from the street. This is in Riverdale, Toronto, and soil conditions are sand.

So let's say the laneway house on its own is $200K, what does adding the full-height (8') basement do? Add an additional $25K? $50K? $75K? Just to clarify, I'm looking for the *additional* cost of adding the basement. Obviously it could house some of the mechanical equipment, for the accommodation above, but it would be wide open, concrete walled, unfinished open space.

Thanks for any insight.

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