Basement under your garage?

[rutbeer]

I have been thinking about how to deal with my shop/garage problem. I live in a downtown area, so lot size is tiny and there are pretty strict zoning codes with what you can rebuild once you tear down something that was grandfathered in. My garage is tiny....barely two cars wide. If I tear it down, I will have to move it further from the alley and possibly further from my neighbor's garage. (though this is probably the cheapest option). I was considering digging the garage down and pouring a basement underneath it. No small task! then basically installing a four post car lift with a "floor" above it. I have seen lots of these on the internet, so not a new idea. Basically, you drive your play car in, lower the lift so that it drops into the basement, then the "roof" of the lift becomes the floor for the upper garage.
Total Lifting Solutions - Car Parking Lifts, Car Turntables, Parking Solutions, and Goods Lifts.

That's a spendy way of doing it. Was thinking about converting this lift to have a "second floor". Costco - Dannmar 4-post Portable Parking & Storage Lift Starting at $1,899.99

Not a priority project, but parking right now is complete beotch and my garage already needs a lot of work to be usable.

Another option, if I can get zoning approval, it to remove the flat roof, and go up with a steep gable. The lift could go on the main level, then it's basically a service lift as well. However, that means the lift needs to be in the center so that I will have clearance above and it will limit usable floor space in the garage. Basically making the garage a two car with some room around vs. a three car with basement shop.
Oh, and security is a big deal too. The basement option puts everything out of sight. Damn alleys bring the the crooks through every weekend. I haven't, but my neighbors have had regular break-ins from the alley and lost tools, bikes, etc. With the basement lift, a peer through the window shows nothing there.

 

[D'Animal]

Before you dig your basement out, check for flood plain and flooding history over 100 years.

I love the lift idea but the Dannmar Maximum Rise: 70-1/2". It does not mention if it is to the top of the rail or the bottom. You would also have to figure in approach angle if you sloped you driveway.

 

[rutbeer]

I wasn't that specific with the link. The "X" model is the one I need. It raises to 89 or something like that.
Commander 7000x Specifications:

Lifting Capacity: 7,000 lbs.
Overall Width: 117”
Outside Length: 194 1/2”
Overall Length with Approach Ramps: 227 1/2”
Height Columns: 94”
Minimum Runway Height: 4-1/2”
Maximum Rise: 85”
Maximum Lifting Height: 89"
Width Between Columns: 103”
Runway Width: 18-5/8”
Width Between Runways: 37-1/2”
Length of Runways: 185”
Locking Positions: 13 Lock
Spacing: Every 4-1/2”
Lifting Time: 45 Seconds (Depends on Weight of vehicle)
Standard Motor: 110 VAC 60Hz. 1Ph

I would need a shop drawing of it, or some time over at my Dad's neighbor's house to measure one. My guess is that I would need to trim the post tops to bolt them to the floor above, then I would need to raise the ramps height so that they were flush to the floor when in the up position. Dunno....really just brainstorming right now. There are a lot of questions about all of it. I'm less worried about the lift than I am about exactly how to undermine the footings and pour a wall under them.

 

[se2000]

Do you have room to expand the garage on the ground? If you do, that will be the simplest solution. I know a guy who had a 1 car victorian that he added an "L" to the back so street side looked original.
Check with your building dept but usually if 1 original wall stays, it is still grandfathered.

 

[rutbeer]

You are correct. I could leave the alley wall and the side wall, and move/rebuild the other two. That would certainly be less money. Money isn't the only factor here though. Yard space, if I care to keep any, is at a premium, and expanding the garage sideways still exposes what I have done to the public. Basically, if the wife leaves the garage door open one day, all my chit is gone. If it was underground, they do a quick drive by, see nothing, and move on. I could even lock the trap door so that you couldn't even get to the basement. If you have seen Mr and Mrs. Smith, that's basically what I'm talking about. Think one car bay with shop space in the basement. You access that through a hatch in the slab with an aluminum ladder. So, 2 cars up for daily drivers, one project car and tools concealed in the basement.

 

[se2000]

A garage behind a garage, second door would help. A second story shop over garage.
As far as going down, your old foundation would be gone, no legal way to be grandfathered in. And alley way are usually where all the utilities go. Have you called dig safe yet?

 

[rutbeer]

Nope. Pipe dream at the moment. No need to call any gov't authority until I have a grasp on cost implications and reality. But....water comes from the street, sewer goes to the alley. I had the sewer video scoped and video recorded. I know where it goes and I'm clear. Having ANY utility going under an existing original structure on purpose, would be pretty insane. I have no idea why they would have ever done that. Besides, I would excavate by hand and the purpose of a secret room is that it's a secret!
The original question (though never really posted) was really, HOW exactly would you go about excavating, underpinning, then putting a wall directly under an existing wall?

 

[se2000]

Dig safe or whatever they call it in your area is not a government agency. It is a utility thing. City houses have all kinds of things under them. Some not even connected to you.
To dig out, you'd have to remove the floor and dig down keeping away from the edges by at least a foot. then you could put up a temporary wall to hold up the roof while you take out the old footing. I'd do it in sections on the load bearing walls. I'd rent or buy one of those mini excavators to do the digging. They are not noisy and you could just play load music to cover it. Get a enclosed trailer to haul away the dirt. You are going to need several yards of cement. Were you planning on mixing this yourself?
There is no way to do this in any sane method by hand.
Best bet is to get your permit, get in the big machinery and a crew to dig the basement and pour walls. You'll need a pro to design and build your cement or steel framing to support the main floor. You don't want it crashing into the basement. No one is going to think twice about a garage basement. A week after it is closed in, all will be forgotten

 

[rutbeer]

True. My neighbors would call me on the permit thing in about a day anyway. Old people
Honestly, I don't think keeping a foot away from the wall would be enough. We have strange soils in Colorado, so there's a real good chance that would collapse. I thought the best way might be to excavate "columns" of dirt out every 5' and pour footings at the bottom. Insert floor jack columns, brace the heck out of the wall to keep it from tipping, and then excavate the rest of the dirt from under the wall. I think the only way to do that is one wall at a time.....or just wreck all but the two walls needed to maintain setbacks and build an interior wall on those side. Eh....pipe dream as I said.

 

[se2000]

I did mention doing it in sections or columns. Doesn't matter if it did collapse once you had the temporary wall built to support the structure. You could still do that for the 2 grandfather walls.

 

[PAToyota]

As far as going down, your old foundation would be gone, no legal way to be grandfathered in.

Not exactly true. I've seen a number of instances of basements being dug under houses in such situations. Typically, the main structure and the footprint are what matter - not the foundation itself.

For the houses, the structure is typically lifted as though you were going to move the house. Cribbing is set up and beams are slid under the house to support it. The house is usually lifted somewhat (you'll see why later). Then they go in with skidloaders and mini excavators to dig out under the house and prepare for the new foundation. The foundation is poured, the foundation walls are built, and then the house is set back down onto it.

I've also seen lifts done to create what you are proposing. Not an inexpensive option, mind you. And you may run into regulatory issues trying to "jury-rig" a lift that wasn't exactly meant for this purpose - either with your municipality or your insurance.

 

[se2000]

I think you misunderstood my statement. We are in agreement. The old foundation would be gone because to build the basement, you would have to go down 8 -10 feet, not the 4' or less that is there. Better to demo the old foundation and pour all new. All you have to do is use the temp wall inside structure to carry weight. then pour new foundation up to the old baseplate. This would avoid lifting the structure if it were to remain intact.
I firmly believe that this is not practical and view it simply as a mental exercise. Way cheaper to buy an existing garage in some industrial area or buy some land out in the country and build a garage/workshop/weekend home

 

[rutbeer]

Mental exercise- yes. This is a long term what-if project that I was just brainstorming about.
I may not have mentioned it earlier, and don't feel like reading back through at the moment, but the walls are 9" of brick! No studs here, so supporting the roof really isn't the issue. Supporting that much weight of a solid brick wall is....