basement under new garage

boustany · Aug 5, 2004

Not cheap ....

Any idea how much it costs? When I do my workshop I plan on having a basement, but not below where the vehicle could reach, so I'd be curious to know how much a a slab like this would cost.

The basement is actually planned to save money. I have 16" of topsoil, so I have limited non-topsoil for backfill and so on. I spent about $3 or $4,000 on granular A just to bring the floor of my barn up high enough for the slab. /forums/images/graemlins/crazy.gif

If I make a small basement I get storage space and loads of free material, with only the additional cost of a wall.

bandit67 · Aug 5, 2004

I've dealt with this scenario occasionally over the years working for builders and various Architectural firms. Most of the garage over room designs happen in mult-million dollar homes.

It can be done with either pre-cast or poured-in-place slabs, as others have mentioned, but it will be very expensive, and ends up being cost prohibitive in 95% of the cases. It's usually only done for clients who just have way too much money on their hands and do it just because they want to. If you are of average wealth status, my guess is that you'll give up on the idea once you find out the cost per square foot of a room under the garage.

But like I said, if you've got a lot of dough laying around and think it'd be cool to have a room under your garage, then find yourself a good structural engineer and have at it. We'll want to see pictures of the finished product, of course. /forums/images/graemlins/cool.gif

herdfan · Aug 5, 2004

We have just run into this situation with our new home.
Due to compaction issues, our builder had to cut down to good ground under our garage and pour a footer.
Instead of letting the footer be used to help support a garage slab over top of fill, We are going with the basement under the garage.
It's an oversized 3 car garage (24x40) and the additional cost is $22k.
Lots of cash, but the $/SF aint too bad.

Junkman · Aug 5, 2004

That is a little less than $23 per square foot. I don't see that as any different than any other square footage costs to the home, and if you plan it right, you can have a second garage under the first. Just a thought if you decide that you want to collect cars or tractors... /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Ben_W · Aug 5, 2004

It was 15 years ago and if I remember right the 4' by 24' prestressed slabs were $600 apiece. I don't know how much poured walls go for now, but one wall was going in for the basement of the house anyway so I had to pay for the 3 extra walls. I don't remember for sure but, I don't think I had to have footings dug for the garage so that helped with the price of the walls. With a regular slab garage footings would have been poured. I also had the floor poured in the lower garage so that added some to it.

bandit67 · Aug 6, 2004

That's actually a pretty good price for basement SF under the garage! Most of the ones I've seen around here are up at $70/sf +! Guess it all depends on who's doing it and what part of the country. Then again, many of the ones I've seen were much bigger, nice finishes, etc., and I'm sure a lot of the higher costs were associated with the bigger spans.

herdfan · Aug 7, 2004

( if you plan it right, you can have a second garage under the first. Just a thought if you decide that you want to collect cars or tractors... )

It will really help us do some neat things.
We plan on putting in a home theater and a gym under there.
As for the extra cars . . . /forums/images/graemlins/grin.gif

Junkman · Aug 7, 2004

Since polygamy is illegal, then old cars are the second best thing..... /forums/images/graemlins/crazy.gif /forums/images/graemlins/blush.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/wink.gif /forums/images/graemlins/wink.gif Besides, old cars aren't as expensive a old wives.... /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/crazy.gif /forums/images/graemlins/crazy.gif /forums/images/graemlins/crazy.gif

DaveNay · Aug 8, 2004

( ... as expensive a old wives.... )

Young wives are even more expensive.....especially if the old wife finds out. /forums/images/graemlins/shocked.gif /forums/images/graemlins/shocked.gif

Dave

ELMO67 · Aug 9, 2004

Zone V, where do you live? This might give us some idea of a solution to your question. I live in Eastern Ct., this is what I did. I have a house with a walkout basement and wanted to add an attached garage. We ended up adding a 10x 12 mudroom and a 28x 28 garage, both with a full basement below them, the access to the garage is either through the existing walkout doors, or through a 9x 7'6 overhead door that was planned for when the concrete was poured ( the concrete walls are 12' high). Now the floor system is pretty simple, consisting of a single 16'' x (I think) 45lb. I-beam. Sitting on top of this are 4"x9" hemlock joists with 3" t&g hemlock flooring nailed to it with 6" spikes- that's it. I also have a stairway to travel up and down with over in the corner. The building inspectors only comment was " A wood floor is permissible in a residential application only". This may or may not be the case in your area, but it worked for me, the price was right? and it really looks great. I purchased the building plans ( of my own design and dimensions) from Sigfriedson Wood Products in Brooklyn, Ct.; these plans included an "engineers stamp" for the price. Hope this helps /forums/images/graemlins/smile.gif