Multi-car underground garage

[devin98]

Hey Everyone,

I am located just outside of Toronto, Ontario Canada. We are in the early stages of planning a fairly large addition to our home and I am considering adding a large underground parking garage.

Background:

We have a ultra modern 5500sqft home on 2.6 acres of property. The renovation idea started when we wanted a larger master bedroom and washroom and has ballooned from there into a indoor pool, master bedroom and now possibly a large underground garage.

Right now we are in touch with a few different architects and I think we have a firm we would like to work with.

Right now the home only has a two bay 2 car garage which is way undersized for what we need, I can't go much wider then the house is now and I don't really want to go deeper (tandem parking is a pain) so I was considering removing one of the garage bays and creating a drive down ramp to an underground garage. Since I need to pour a new foundation for the addition and we don't need to space in the basement why not make it a parking garage with a glass wall between the garage space and my pool room/bar (pool table) to enjoy the cars when not being driven.

I am having a hard time finding projects like this as a jumping off point and no idea on the budget does a project like this cost $50,000 or $500,000 what needs to be considered?

Any ideas and inputs would be greatly appreciated.

Thanks
-Devin

 

[thewatusi]

I would think that the square footage consumed by a ramp at a reasonable grade and an area to turn cars around would make the project impractical.

If you've got money to burn why not an elevator to bring the cars to the lower level?

 

[devin98]

I would think that the square footage consumed by a ramp at a reasonable grade and an area to turn cars around would make the project impractical.

If you've got money to burn why not an elevator to bring the cars to the lower level?

I thought of a lift to get down to the basement parking but I worry about long term maintenance and breakdowns.

You do bring up a good point about the grade. My current garage bay is 35ft long and I was planning an addition that would be 20 ft out the back. I wonder if 55ft would be enough to drop 8ft below grade and be able to make the turn.

 

[thewatusi]

I wonder if 55ft would be enough to drop 8ft below grade and be able to make the turn.

Even without making a turn that's about a 15% slope...extremely steep. You'll also need to account for the thicknesses of the first floor/lower level ceiling.

Do a google image search for "parking lot turn radius" to get an idea on how much room you'll need to turn.

 

[toplessHO]

May want to research this
underground parking garage in Detroit I think
A whole subdivision of multi million dollar car collections.
To me the elevator makes the most sense and the 2 car garage
can still be used (parking a car on the lift platform).

 

[Allgonquin]

Call Steve here. He used to be a frequent poster on this board.

http://www.ultimategarage.com

He has designed a few underground garages.

 

[admranger]

Don't forget about the ventilation requirements and fire protection you'll need. With that much land, is there no room for a 'normal' garage elsewhere on the property?

 

[Lippyp]

The vast majority of new houses in France have a garage underneath, it's usually a combination of part hole and part above ground with the soil thats dug out piled around the house so it ends up looking like the house is set on a small mound, That way you don't need a s steep a ramp as a pure underground garage.

Fot a space saver you can buy a vehicle turntable so you can drive in, spin the car around and park it backwards so its facing the exit. You can buy these in manual or powered form. I used to have a customer years ago who had basement parking with a turntable and a couple of the guys that worked there had worked out the exact speed you needed to drive onto the turntable at and then yank the handbrake on which spun the turntable around the right amount, a bit like a Ken Block stunt.

If you have the space then I don't see why its not feasible to do at all. even easier if you are on a slope. Ventilation just needs to maybe be an extractor fan switched by the door opening.

 

[kansei]

I agree with Allgonequin, Steve will likely know all the ins and outs to consider.

That said, I asked a contractor here about it once about eight years ago. I had the same idea, except using the entire two car garage as the entry ramp, figuring that would give me an extra 10-12 feet of width at the bottom of the ramp to ease turning. My thought was to have the actual parking area another 20 feet or so deep to the immediate left of the width of the two car garage ramp, with the entire added-on 'parking garage' slab being a minimum of 50 feet long and 42 feet wide (not including the footprint of the existing garage that would become the beginning of the ramp. I quickly realized, as others have already pointed out, that the grade would still be too steep for lower-ground-clearance cars, and I would lose the first 25 feet or so into the new garage area to compensate for this. Unless you have the room, money and approvals to create a rather enormous subterranean garage, I'd go with the elevator idea- provided, of course, you can afford it. I wouldn't use a lift for it either, look into a true automotive/cargo elevator.

All the above aside, as others have pointed out, you run into the myriad of other concerns and codes to meet for air quality (fixed gas monitoring system), fire suppression system, drainage and flood control, emergency exits, etc. When I casually checked into this, I quickly got priced way out of the game, pretty much from the beginning. My contractor had me check with contractors experienced in parking garages, since that is essentially what you would be building, and would have to follow a lot of the same code requirements. The rough guesstimate I was given for just the permits, excavation, slab pour and walls built to minimum parking garage standards for a 50 foot wide clear span- no second story yet, with a long enough ramp, and room to install five storage lifts off to one side at the base of the ramp was "...at least $250,000". Building a home addition of any sort above that, using Spancrete as a "roof" over the new garage area was going to cost even more than the garage pour, mostly due to the cost of the Spancrete.

I'm obviously not a builder, but I'd say you are looking at a $300-500,000 project, easily.

Keep us all updated on what transpires, even if it is for a route you opt out of. I know a lot of us are curious about what you are told.


Neal.

 

[zxttfan]

Do you have the ability/yard space to build a driveway/ramp next to the existing garage that could be correctly sloped down to the new basement with a vehicle entry door at the rear or to the side? Excavating and retaining wall costs will be expensive if your lot is flat but should be cheaper than tons of reinforced concrete and a dedicated car elevator. It would also allow you to keep the existing two bay garage for the daily drivers.

 

[kbs2244]

I think the angle at both the top and bottom is going to be too much for street cars.
But, with some research on approach and leave angles for the cars you have or may get, and some graph paper, you should be able to figure it out.
Because of that, I would go with a lift.
They are in metro parking garages in 24/365 use, so they can be built to take any strain you will put on one.

 

[Bondo]

Ayuh,..... Space-wise,....

Underground parkin' don't make any sense, unless you've got a hillside to work with,....

On flat ground, ya loose more than ya gain,....