Building a shop...concrete slab question!!!

What up fellas....well im finally building my shop behind my house and I have some questions as I have no idea about concrete slabs and id like to know a little so I dont get taken by someone....so here it goes.  I'm building a 30x30....that will have one 2-post lift....What thickness should it be poured... What size beams should be poured and at what width/lenghts of the slab....What size rebar should be used...and if anyone is in the business and can give me a rough estimate on the cost that would be sweet. IDK anyone in particular in the business so im going into it kinda blindly...Thanks guys.

You're looking $3,000 on the low side, and $8,000 on the high side. Depends on what kind of grading you need to do, etc. I'm not sure about the soil down around your area, but here in DFW we'de probably do a 6-8" slab with grade beams and some thickened footers where your posts for the lifts will mount. Concrete and rebar are DIRT cheap right now so if you're going to do it, do it NOW!!. Up here we are getting concrete between $70-80/CY and rebar for about $0.30/LB. Don't be affraid to talk to some guys out doing commercial work or roadway paving. Alot of them will do side jobs on the weekends and save you some money. If you get these guys they know what they are doing and can make sure you get something good. I do soem side jobs up here when they come along. I just poured our new patio this spring (20 CY of concrete) and at the same time did my neighbors. I was able to do his (about an 8 CY addition) for about $1500. I would say if you do some shopping you should easily get it done under $5000 and get a quality job. Just make sure you get two to three prices if you can.

when i sold wheels the place i worked for sold lifts too , i think in commercial buildings the concrete had to 12 to 16 in deep & have the threaded rod tied into it with rebarbthats been about 7 years ago so doubt its changed, you should check with the codes dept. in your city check out http://americantiredistributors.com to see if they can get you to a dealer in your areajt

Thanks for the info guys....the area is already pretty level...there will be minimal grading needed. The soil is a top soil/sand mix I believe...it stays pretty solid no matter how much rain we get. When I built my fence it was a huge PITA to get the post holes dug so I know the soil is pretty solid. Im gonna put in a 9k lift...for the most part there will never be anything larger than a 5-6k truck on it...I know the beams run on the outside of the slab....should there be beams running through the center of the slab as well....thanks again guys.

Edited: 9/24/2009 5:29:56 PM by scortboy

You might do beams every 10' each way if you really want to beef it up. You're looking at maybe an extra 5 CY of concrete which would be about 400 bucks, plus about another $500 bucks to trench the beams. It's probably worth it. Altogether if you did an 8" thick slab, beams as a mentioned above, and a beam around the outside, You're looking at about 35-40 CY of concrete, which would be about $3200. You'd probably have about 1000 Lbs in rebar, so add another $300 for rebar, and if you got 6 guys to do the work and paid em around $200 for the day you'd be about $1200 for the labor. Throw in another $150 for formwork and another $200 for misc., and $200 for a trencher and you're looking at Just over $5200. 

about 2 years ago I did a 40x60 3 bay steel building and got screwed when it came to my foundation because the inspectors here made me have it engineered.. How ever it is right. has 24" deep 16" wide footing all the way around. 5' x5' 36" deep footings everywhere there is a support beem. rebar throughout...cages built into each footing. Bolts interlock into the cages...supposedly a 200mph wind could hit the building and I have enough concrete to hold the building down! my arguement is that all the sheet metal will be gone anyway, but they didnt wanna hear it. I have 96cy, 3/4" rebar, grading and all ran me about $16,000 which was actually a good deal considering the work. The guy I contracted to do it ended up doing it for cost...( neither of us expected it to be THAT involved and he was happy just having some work for his crew at the time)

i myself have been in the concrete business for 9yrs doing commercial work. but 3yrs ago we had built a 36x48 garage at home. our slab was only 4in with 1/2 rebar every 3ft each way. we have got a 9k lift. then we layed out where it would be sitting then dug a 2ft x 2ft  square where the post would be sitting and dig an additional 12in deeper. put some extra bars down into the hole to reinforce it. then where the garage doors will be make it 1ft thick and about a 1ft back and make sure it slopes back and not straight up. that just creates a definite crack point. but there is one thing you can guarantee about concrete is that it will crack sometime or another. and when it is poured a rule of thumb when putting the saw cuts in is not to exceed 16ft. but if your 30x30 you could just slice down the middle both ways. or if for some reasons you would have any corners inside where concrete is poured around it you wanna cut off the corner somehow. cause those are definite crack points. and on our lift ive had 7k to 8k trucks on the lift and not had any problems. so hope this helps you out at all. that you dont have to go overkill.

Ive been doing concrete for 10 years and you definately need at least 4 inches. Most garage floors are only 4 inches. You do need to have a trenched footing on the outside walls and where the posts of the building and lift are. 1/2 rebar is strong enough for what you are doing. I would do joints every 10 ft. If you have a column in there then do a diamond cut around the post. Buy the way i would go 5" on the floor if it were mine. Most commercial/industrial floors are from 6" -8" on up. 

Thanks for the help guys...ive found a couple people to come out and give me estimates...ima pick their minds a little bit and see exactly how they wanna do it...then compare it to their price and make some deals. I have a hook up on concrete so i gotta make sure theyll do it if the cost of the concrete isn't in the deal at all. I can get the crete for close to 1/2 price...so hopefully within the next week or so I can get it going. Thatnks for the help guys...its definately helped out.

Also might want to get the fiberglass reinforced concrete....I done this with the slab for my 24x40...just had it poured about two months ago