underground garage sqft calc

[Mr Fixit]

hello Group,
I am new here and like what I have been reading Thanks. I did a search for sqft costs for concrete and had no luck. I am wanting to build into a hillside, this may be a better description of the garage. I am after budget information just to get started with planning and was wondering if anyone could toss a figure out. I am a home owner looking at building this with some sub's help for the project. Our future plan is to build a 900sqft apartment on top at ground level for the parents if needed later. I realize this is not very much information so let me know if I need to give more.
TX Chris
:)

[Bogenconcrete]

Hi Chris,

I would suggest that you determine all your estimated measurements and contact your local ready mix supplier. They will most likely be able to give you some idea of the costs involved for the concrete if you plan on doing the job yourself.

[Mr Fixit]

Bogen,
Thanks for the reply and suggestion I will do this. I was wondering if there was a Sqft calc like for framing, you here a figure quoted of $XX-$XXX per sqft is there any equal #s or figure for concrete when you are doing what I am planning and just getting rough numbers.
TX Chris :)

[Rich]

http://www.construction-resource.com/calculators/foundation.php for the stemwalls - probably want to use 115 / cy for concrete cost. The calculator will give you a good idea but it's not perfect and doesn't account for site conditions, etc.
And for a slab you can assume anywhere from 2.70 - 5.25 / sf.
None of these numbers include excavation.

[Richard A Hetzel]

If you're building deeply into a hillside, the back wall may need to be a cantilever retaining wall, unless you plan on a structure above immediately. They can run a few hundred dollars a linear foot. It all depends on what the temporary roof structure will be, and will also depend on how much front wall you have left after the garage doors are taken into account.

[Mr Fixit]

Thanks Guys, This is the early phase of the project and you have provided me with exactally what I was after.
TX Chris
Happy Holidays to everyone. :D