Garage with Basement?

[BoostAddiction]

Although I enjoy the Garagenous Zone, I am thinking about building another garage. This would be just opposite the existing attached garage, but would be a standalone structure. It would be either 2+ or 3+ cars wide but not very deep (though I have a 5-acre lot, it is irregularly shaped and a property line will likely dictate the depth I can build).

To the point, I am thinking about building this garage with a basement. The land slopes away from the front of the garage and with a little effort I think I could have, in effect, a three-level garage (basement, main level and upper level) just like my house.

I've already talked to an architect and he says it is not only do-able, but probably won't cost much more than digging and filling the foundation. It evidently involves pouring the main floor on pre-made steel "pans" that are supported from below.

I could use the garage basement to store car parts, seasonal stuff, and lawn care things, especially the lawn tractor and it's appurtances. I'd plan to have a mini-garage door (something like 7' high and 5 or 6' wide) so I could drive the tractor in and load larger things.

My question is: has anyone else done this? How did it work out? Were the costs reasonable?

Thanks,

-Will

 

[bmwpower]

Interesting idea. I know it can be done, too. Local guy here who owns a precast concrete company built his house in a similar manner.

Any plans on a lift? I would think that would be out of the question on the main floor.

Also, I would think it would cost more your architect is leading you to believe. No only do you have the full foundation, but the concrete floor below to pay for. In addition, the concrete of the main floor would need to be thicker than the nominal 4" (more cost). Plus, not sure what the cost of the steel would be, but it can't be cheap at today's prices. I wonder what precast would run?

Don't get me wrong, it sounds like a good idea and something you should look into.

 

[DocsMachine]

That's been a dream I've had for a while now.

Many years ago, I worked at one of those oil-change places; you know, drive in, get your oil changed, fluids topped up, etc.

Anyway, it was built like your idea, the building was built over a complete basement, with the working bays at ground level. There were slots in the floor, with low raised lips (angle iron) that the cars drove over and parked.

From below, there was a raised platform under each slot/bay. The platform was expanded metal, and open to the rest of the "basement". It had sliding panels that had the tool selections, and some gizmo for letting the oil drain into. (The drain tank took up a fair chunk of one end of the basement.)

If I had the elusive infinite funds, I'd sure think about something like that. At least one slot anyway, like the old fashioned grease pits, except bigger, better ventilated and fancier.

Make yourself a dumbwaiter type elevator, and have the downstairs as mainly storage, especially if you tend to collect heavy stuff like lots of engines and transmissions.

Doc.

 

[larry4406]

my brother is a builder as am i, and he has built three garages with basements and is currently working on a forth.

In terms of cost, you have to now pay for two slabs. The basement slab is a conventional slab on grade. The first floor slab is much more involved and the foundation has to be strengthened to provide proper support for the upper slab. He has done it two different ways.

Method 1 involved massive steel intermediate beams running the depth of the garage, two beams evenly spaced on the three car garage. A plywood form was built which planed out with the top flange of the steel beam. Extensive vertical framing off the basement slab (poured first and cured) prevented the plywood from caving in. The first floor slab is a structural slab and used an extensive amount of rebar. The steel beams and rebar pattern were spec'd out by the architect. The plywood forms were stripped after the pour.

Method 2 is almost the same except that he used corrugated metal decking like is used on commercial jobs. This took the place of the plywood form. The corrugated metal is supposed to be self supporting and thus not require the temporary vertical supports. He supported it anyway. The metal decking remains a permanent part of the slab.

hope this helps. good luck

 

[HighOctane]

Sounds like a great plan But yes Like BMW says you should look into, it does sound like great plan though, it just might cost more then the architect is leading you to believe, and if you want to add a third level on top then that will add a bit of money too. I like the Idea though

 

[Rickster]

You'd need a set of tools for each level ... what a great idea!

 

[mleichtle]

Have your arch. look into prestressed concrete panels. A company near me is called spancrete. http://www.spancrete.com/sf_garage.html

I see this more and more in the custom homes around here.

 

[DIGGER_DAVE]

Have your arch. look into prestressed concrete panels. A company near me is called spancrete. http://www.spancrete.com/sf_garage.html

I see this more and more in the custom homes around here.

Another way ...

A fellow I know built a THREE story garage. From the front (driveway entrance) it looks like a high pitched roof two story building (the top floor, which uses 2" x 12" floor joists) he uses for storage.

The main level concrete floor (which acts as the roof of the basement) is made of ONE SINGLE slab done with POST TENTIONED concrete.

POST TENTIONED slabs are placed with tubes (poly) in them and steel cables inside the tubes. After the concrete has set and cured; a special hydraulic "puller" tensions the steel cables with the end result of a VERY strong self supporting CLEAR SPAN floor. (his is 40' x 24')

He is in the business of doing these kinds of slabs and said it would be too expensive to do for the average shop unless you want a perfectly smooth floor.

He enters the basement from the rear of the garage. (the building is positioned in the side of a hill)

 

[bobx]

you guys have WAAAAY too much $$$...

good luck though.

 

[mleichtle]

Another way ...

A fellow I know built a THREE story garage. From the front (driveway entrance) it looks like a high pitched roof two story building (the top floor, which uses 2" x 12" floor joists) he uses for storage.

The main level concrete floor (which acts as the roof of the basement) is made of ONE SINGLE slab done with POST TENTIONED concrete.

POST TENTIONED slabs are placed with tubes (poly) in them and steel cables inside the tubes. After the concrete has set and cured; a special hydraulic "puller" tensions the steel cables with the end result of a VERY strong self supporting CLEAR SPAN floor. (his is 40' x 24')

He is in the business of doing these kinds of slabs and said it would be too expensive to do for the average shop unless you want a perfectly smooth floor.

He enters the basement from the rear of the garage. (the building is positioned in the side of a hill)

Thats interesting. I toured the spancrete plant. They extrude the plank (600 feet) with the cables tensioned in it. Then cut it to the ordered lengthes. When they cut, it crowns. Then its just craned into place, and covered with 2" or so of topping concrete. They design the whole floor system for what ever holes you might need.

 

[Donzi4me]

Neighbor near did this to his garage. He put in a 10' walkout basement foundation. But on the main level he just ran joists and made it his shop. It is 5 cars wide and one big a$$ shop above it. From the front it looks like a one story building. Drive around back to access the garage.

 

[Krodad]

This is done all the time nowadays. I work with builders that can do this for surprisingly little compared to a backfilled frost footing. How "little" is relative...it will be the cheapest square footage you can possibly get.

Hollowcore panels from a precaster is a decent option, post tensioned slabs act in a similar way (the precast panels are prestressed) but you must be very careful about future cutouts in a post tensioned slab as the strands cannot be cut without bad things happening...prestressed precast slabs can be cut anywhere without problems.

I would consider the other option, which is something like the litedeck type product. It will give you insulation in the floor as well if you decide at some point not to heat the lower level, but heat the upper (or vice-versa). This same system is also used as a roof if you so desire.

I have seen unsupported garage floors around 33ft.

www.litedeck.com

 

[boiler7904]

Using a product like Spancrete is definitely cost competitive when you compare to backfilling the original poster's foundation with compacted sand or stone. The real question will be if strucutral steel will need to run down middle of the building to support the precast plank. There are a couple of things to think about when working with spancrete.

1. It has a camber to it meaning that it has a bow to it (looks like a empty flatbed semi trailer). You will end up with less concrete topping at midspan than at the ends.
2. Probably have to use 12" foundation walls for plank bearing (3 1/2" is usually minimum requirement).
3. The precast plant will usually only factory cut/core holes with a minimum dimension of 10".

If I was in your position with the land and finances to build a garage, it would definitely have a spancrete / concrete topped floor over a basement.

 

[BoostAddiction]

It's great to hear that others on the board have done this or seen it done.

My architect/engineer says he's done this, generally using the metal pans onto which concrete is poured approach.

In my case, there is a substantial amount of foundation work that has to be done because of the soil and the slope of the lot where the garage would be located. The current thinking is that there would be a relatively small upgrade (around $2000) to make the lower level a basement, compared to digging and filling. I'm not at the bidding stage yet so I don't really know how accurate this is, but it did come from a guy who builds several houses a year, and designs many more.

The idea of prestressed concrete never came up and I think it is worth pursuing as an alternative, as is the conventional way that commercial buildings are built using forms that are just moved up to the next level when that floor needs to be poured.

This is a project that won't happen real soon, so I have the chance to explore a lot of options.

I've been thinking about how I would use the structure and am considering the idea (as someone else mentioned earlier) of a dumb-waiter or poor-mans freight elevator to move things up and down from the main level to the basement level. Another idea would be to have a whole-car elevator to raise and lower vehicles to add more parking. I'm guesing this would be too expensive, though.

Another idea is to use ICF, which would make it possibly cheaper to create a foundation shape that was a little more interesting.

Keep the ideas coming- it's all very instructive!

-Will

 

[bmwpower]

Re: the car elevator idea.... I wonder if you could somehow integrate a 2 post drive-on lift into the mix. It would have to have the extended height capability to meet your 1st floor height requirement. Someone had to have done this prior to Jerry Seinfeld.

 

[Stuart in MN]

There's a classic auto sales place just down the street from me. They're in a building that was built in 1911 for a bus manufacturer; it has a main level, a second floor and a basement that are all connected with a big freight elevator, and they can park cars on all three levels. It's a pretty neat place. http://www.yesterdaysauto.com/home.htm

 

[Ed and Sandra]

Re: the car elevator idea.... I wonder if you could somehow integrate a 2 post drive-on lift into the mix. It would have to have the extended height capability to meet your 1st floor height requirement. Someone had to have done this prior to Jerry Seinfeld.

A scissor lift with adequate vertical reach might be a better answer. Take a look at the design of the "elevator" at this site (be sure to give the movie time to load): http://www.aclifts.com/parking/pss-7.asp We absolutely love this setup and wish we had been aware of it before undertaking our garage project so we could have at least considered it.

A do it yourself configuration along the lines of this concept might be an ideal solution.

Best regards,
Ed and Sandra

 

[JMURiz]

There is an old house near me that has what looks like a chauffeur garage. Has a garage, a basement below and a room above. It's in Arlington and I can take pictures if you'd like me to.

 

[Krodad]

It's great to hear that others on the board have done this or seen it done.

My architect/engineer says he's done this, generally using the metal pans onto which concrete is poured approach.

In my case, there is a substantial amount of foundation work that has to be done because of the soil and the slope of the lot where the garage would be located. The current thinking is that there would be a relatively small upgrade (around $2000) to make the lower level a basement, compared to digging and filling. I'm not at the bidding stage yet so I don't really know how accurate this is, but it did come from a guy who builds several houses a year, and designs many more.

The idea of prestressed concrete never came up and I think it is worth pursuing as an alternative, as is the conventional way that commercial buildings are built using forms that are just moved up to the next level when that floor needs to be poured.

This is a project that won't happen real soon, so I have the chance to explore a lot of options.

I've been thinking about how I would use the structure and am considering the idea (as someone else mentioned earlier) of a dumb-waiter or poor-mans freight elevator to move things up and down from the main level to the basement level. Another idea would be to have a whole-car elevator to raise and lower vehicles to add more parking. I'm guesing this would be too expensive, though.

Another idea is to use ICF, which would make it possibly cheaper to create a foundation shape that was a little more interesting.

Keep the ideas coming- it's all very instructive!

-Will

I manage the ICF division for a company, and I can tell you that you would be very happy if you went that route. There are probably a number of ICF specialized contractors in your area that can help you out, and they certainly are familiar with the ICF style floor deck system. I almost never see a requirement for anything thicker than an 8" concrete wall even when supporting a bearing concrete floor. This system is probably still cheaper than even the hollowcore precast planks because you will not be paying for the crane to set panels. I used to work with precasters every day, and while I fully endorse the precast idea, your project size just does not lend itself to the use of precast as a cost competative item, in general.
If it were me, I'd look at building the entire structure with ICF's, except for the roof.

 

[atch]

i went to look at an old car for sale once and commented that the floor in the garage looked like painted plywood. the owner said that it was! and that there was another garage under the one we were standing in. i never went downstairs, but he said that he built it with two by something joists on 12" centers, put two layers of 3/4" plywood over it, painted it with floor paint, and called it done. said it was quite a few years old and was holding up well. the "upstairs" garage had a corvette and a '67 impala in it.

i don't remember how wide the two by floor joists were, and i never asked if there were beams perpendicular to the joists.

maybe not what you're looking for, but food for thought.

the first raised concrete garage floor i was ever around was in the mid-60's when i worked summers on a house building construction crew. we just formed up the upper level with plywood and LOTS of temporary suppports underneath. i still drive by that house occasionally and it's still standing 40 years later. the garages were the same size double garages up and down, probably about 24' square. later, when i was in college, i worked for another contractor who did the same thing on several houses, except that the downstairs rooms didn't have garage doors on them; they had double walk-through doors about 5'-6' wide. as i recall, all of these houses had a steel beam placed into a cavity cast into the top of the basement walls. i can't remember if the beams had a post in the middle or not.

 

[atch]

more (sort of reinforcing what has been said above):

i work in engineering at a hospital and we have an electrical switchgear room built into the upper level of what used to be two story room. this was done by anchoring angle iron to the perimeter concrete walls and running steel beams down the center. then corregated steel forms were laid down which remained in place. the concrete was poured 4" thick over the top of the corregations. these floors are holding up electrical gear that is at least as heavy as a car.

only a structural engineer could say for sure, but it seems to me like this would work just fine for a garage.

 

[Cebby]

If you opted for a lift, you could do it at one end and only have a basement under the "non-lift" areas. Or would you just need footers/piers under the posts?

 

[Tom]

i went to look at an old car for sale once and commented that the floor in the garage looked like painted plywood. the owner said that it was! and that there was another garage under the one we were standing in. i never went downstairs, but he said that he built it with two by something joists on 12" centers, put two layers of 3/4" plywood over it, painted it with floor paint, and called it done. said it was quite a few years old and was holding up well. the "upstairs" garage had a corvette and a '67 impala in it.

Could somebody please expand on this for me? This is exactly what I am looking to do for a future addtion to the back of my present attached garage. There is a slope behind the garage and I was thinking of doing something along the lines of building something similar in construction to a deck but heavier to withstand the weight of a hoist. I shudder to think what it would cost to backfill that area.

 

[ochief98]

I periodically look at this board and just this summer have built a 24 by 26 garage with a lower level basement. I used spancrete flooring for garage floor and ICF walls for the lower level. In the lower level I put a 10 foot garage door, entry door and window. We actually will be using it as a living area until we build our lake home. The lot area was perfect sloping away rather steeply, but i did put retaining walls out from the lower level sides to make a flatter area for the driveway that wraps around from the upper garage. It ended up costing more than I thought it would but it all adds up. so far the lower level is sheet rocked, have not finished yet, and the upper level is stiil being insulated and mudded. The lower level keeps quite warm, though I have 2 8 foot baseboard heaters that warms it room temp in less than an hour. So far, with maybe a few grand more for finishing materials I have nearly 70 grand in it. I will try to post some pics soon!

Ron