I need some advice for a concrete slab.

[SanPatHogger]

Got a price for a 40x64 metal building I want. Found a local guy who sounds like he knows what he's doing. It's going to have a 15,000 pound car/truck lift installed. Where the lift is going has to be 4 inches thick, steel reinforced and 3,500 psi.
I was quoted some crazy numbers up to $45,000 for a slab.
40x64 building, so I should probably go 41x65 to have a little wiggle room?
The local guy said to have an extra 6 inchs around the edge.
What size and how much rebar?
He said I'll need to rent a skid steer to clear and level the ground, but I was thinking about a mini excavator so I could dig out a little deeper for the lift area and the perimeter.
Do I need to do anything to the ground before pouring? I saw a video that said to wet it down with water before pouring to keep the concrete from drying too fast.
I am in South Texas, the ground is mostly clay and sand and shifts quite a bit.
Anything I am missing?
Just for reference I have 1 bow kill and I have not bench pressed anything in a long time.

 

[Milf Dots]

Unless you have a good looking, single female relative between 29-60, I don't have any time for this...

 

[lonegunman762x51]

Call the local concrete company and price the materials. Do the math yourself. 33 or 34 yards of concrete at $250 a yard is about 8,500 for concrete. Most shop floors have minimal steel. Figure rebar and 6 inches or more in trenchs for the base of the lift.

I see about $25k for the concrete work at the high end with that price for mud. These days all contractors are fucking people because California scumbags are moving everywhere and paying buttfuck prices for anything.

If you can do cash and side job it that might help.

 

[Eostech]

$45k and you're doing the ground work?

 

[EGwhisper]

If you’re talking a 2 post there is no way I’d get under anything but a Honda civic with 4”. I’d pour that bitch 12” 4’ square where the columns are going to sit if my life depended on it.

Pay someone to grade and turn down the edges. They will do it in 1/10 the time you can do it in.

1/2” rebar 2’ on center. Make sure the lift it off the ground when they pour.

You can wet the ground at the advice of whoever you hire to do the pour. I’d be more concerned with sun spalting. At the end of the day if it’s fucked up it’s their fault. Do exactly as they recommend and document for any potential fuck ups, go with a different concrete guy if you disagree with how they want to pour.

$3/sf labor here. $200/yard concrete. N Indiana.

 

[texastonk]

40x64x5" is roughly 39.5 yards. 3500 PSI mix with no air is running right at 150 per yard in the Ft Worth area. Could be as high as 180-190 pending where you are in S Tx. 6kish in concrete plus labor and rebar. 45k? he is smoking crack.
As far as the subgrade. I would at minimum scrape off all topsoil and grass. Rip up the soil at least 12" wet it down and recompact it, then fine grade it for concrete. A good 6 mil roll of Polly between dirt and slab would be best as well.
I'm no engineer but I build for a living. a hand full of 2x2 or 4x4 footings under the slab would be better, and at Minium under the location of the lift posts.
You should be able to do this right for under 15k turnkey.

 

[Bradu]

If you’re talking a 2 post there is no way I’d get under anything but a Honda civic with 4”. I’d pour that bitch 12” 4’ square where the columns are going to sit if my life depended on it.

Pay someone to grade and turn down the edges. They will do it in 1/10 the time you can do it in.

1/2” rebar 2’ on center. Make sure the lift it off the ground when they pour.

You can wet the ground at the advice of whoever you hire to do the pour. I’d be more concerned with sun spalting. At the end of the day if it’s fucked up it’s their fault. Do exactly as they recommend and document for any potential fuck ups, go with a different concrete guy if you disagree with how they want to pour.

$3/sf labor here. $200/yard concrete. N Indiana.

This pretty much sums it up. Most lift manufacturers recommend 4-6" but I am a fan of overkill when it comes to lifts.

 

[missed]

There should be a perimeter footing at the minimum. For a metal shop there is typically a 1-1/2" drop ledge so the ends of the metal sheets are below the base angle.
The amount of concrete and rebar is dependant on how much the ground can support. My new garage in northern Arkansas is a 5" slab 4000kpsi with a 2'x2' perimeter footing. 4 #5 rebar in the perimeter footing and 4x4 wire mesh on the top.
I did all the prep and the finishers charged me $1ft to finish. Concrete was $180 per yard. Which what the fuck it was $130 last year.

Only having 4" around a 2 post lift. Nope, I know some lift manufacturers say it's ok. I would have a perimeter footing in that footprint of the lift or piers. A buddy of mine is a civil engineer the flat 4" is not enough if something goes wrong.

There should be a vapor barrier under the concrete also. So wetting the ground pre pour isn't going to help with drying to fast. A decent size pour needs to start as early as possible with a big enough finish crew to get it down and finished. 40' wide will need truck access to both sides or pump it. Pump is going to be probably $2k plus $5/yd. Concrete batch plant can put retarder in the mix if there is concern about it going off too fast. Don't add water to the mix when it's there, it shrinks to much and does bad shit.

What did I miss..

 

[BurtG]

Make sure your base is good.

Not a fan at all of bringing dirt back in I don’t care how you compact it

 

[missed]

 

[ZiaHunter]

The slab will only be as good as the material underneath it. If you have clay in the sub grade the potential for movement will be there which can lead to slab failure. Spend the time to remove any expansive material under the slab and replace with quality fill or crusher fines or screenings. A 5" slab with 3,500 PSI concrete with #3 or #4 rebar on 16" OCEW will be plenty strong with turn down footings. Been a PM on large construction projects my whole career and have on more than one occasion been brought in to try correct slab failures which is very expensive. Best to do it right the first time.

 

[ironpony52]

All the information above sounds very good. I am not going to retype all the advice, figure $4 sq. ft. for concrete if you prep it. the only problem is if something goes wrong concrete guy is going to blame you. The prep is going to be the foundation of your building make sure it is right. A little extra digging and compacted fill goes a long way for minimal money.
Definitely thicken the slab at the post mount areas., thickened edge sounds good too. Wire in the concrete should be fine for reinforcement. Might want some electrical conduit roughed in for lift power, not sure on roof height. I have electrical conduit to the outside of slab for exterior lighting
The building supplier should be supplying sealed prints for the building which should show any needed prep for the concrete such as was mentioned above, lip around exterior for bottom steel channel.

 

[Haney]

Make sure your base is good.

Not a fan at all of bringing dirt back in I don’t care how you compact it

"Not a fan at all of bringing dirt back in I don’t care how you compact it."

OP, don't listen to this bullshit . Obviously he knows nothing about this subject .