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 .

 

[SanPatHogger]

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

No. That was me doing nothing.

 

[XP1K]

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.

How far south in south Texas? I know a good concrete guy out of bay city. Not sure how far he goes for work, but he's good, and he's fair. If your in his area.

Pouring extra slab outside the building seems crazy to me. Shouldn't need any more than the building size. You should have a detail on the footprint of the building. Anchor bolt layouts, door openings, that sort of stuff.

In my barn, I poured a 4" interior slab. I think. 12x24 beam around the perimeter and across the center of the slab in both directions. 3/8 rod on 16" centers in the mat, and 1/2" rod in the beams.

Poured 30x30 for a parking area in front of my barn. 6" thick, 1/2" rod on 12" centers. No beams. It's held up good.

 

[SanPatHogger]

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.

These are the numbers from the lift company. Also, my lift guy is pretty good. Him and his dad have been around a long time.

 

[BurtG]

"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 .

Yeah I’m not talking about pads for a 4 wheeler or car.

I have 48’ pads that get 6 million pounds put on them. Drives that get 1000+ over loaded semis yearly. Shops that get all kinds of heavy equipment Including point loads when jacking them up.


You know the only one that has cracks and settlement ?
The brick around my pool where the idiots brought dirt back in. Only place that isn’t cracked is where I made them put sonotubes in.

Those guys prolly laugh about bringing dirt in being a bad idea like you do.

 

[Woodlanddude]

Thinking for the lift foundation area 4" or 5" is light, but I haven't designed a slab in a hot decade, and only for ag equipment, never a lift. A good article that looks more reasonable since you noted 15,000lbs support (note the 4,000 psi-5,000 psi min. strength in the article):

https://heavydutygarage.com/blogs/news/car-lift-concrete-requirements-thickness-psi-slab-prep-tips

The best way is always to pay an engineering firm to design something like this when human life is on the line (I may be biased as I am an engineer). I would at minimum try to contact the lift manufacturer as they likely have design recommendations for minimum dimensions, concrete strength and reinforcement. Your subgrade material and soils underneath do matter. Local firms should be familiar with working on the geology and soils you have. If you want to really be assured of safety, Quality Control testing of the concrete is usually not cost prohibitive (in comparison to the other costs involved here) to get a couple cylinders broke to check 28 day strength and have air entrainment and slump checked on the trucks when they pour(many concrete companies offer this as a service, but some will refer you to a local lab/engineer). Make sure the concrete in any footing and especially around the supports/beams gets vibrated well to ensure good consolidation as voids could make for a bad day here. Since you are contracting this you can specify you want copies of the QA/QC test results for your records. Find out if part of that $45k included the QA/QC testing as that may explain some of it.

 

[SanPatHogger]

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.

This is a cash side job. I'd like to be $20,000 or under.
The $45,000 guys are talking about having beams underneath and several 24 inch trenches. I'm not launching a space shuttle off of it, just a S type metal building with a lift near one end. I need to be able to lift up to an F450.

 

[ZiaHunter]

Should also mention the lift manufacturer most likely has a recommend footing design for the base plates and may even provide a shop drawing. You need to follow the recommendation because if you don't and have a failure you will have little recourse.

 

[SanPatHogger]

Also, thank you guys for the information.

 

[BCP]

You're probably going to be ~5 trucks worth of concrete or more (so figure 7500 at least) and then all the labor in setting it up. Get a good tractor guy to level the pad and then form it up yourself if you know how, rake the gravel, tie off steel rebar 18-24" on center, footings under your lift, then hire a crew to come in and pour/finish it. That should get you under 20k. You might want footings all around the perimeter but that's going to add a bunch more concrete, probably up the budget to near 10k.

Here in arizona we have this shitty dirt so slabs/concrete are poured thick we had 90 yards of concrete in a foundation for a 3800ft house and then the 1500' garage slab was a whole bunch more concrete.

 

[hollowoutadime]

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.

I bought a mini excavator (Kubota diesel) about 6 weeks ago, I have about 15 hours on it. They're very good at trenching, digging holes for trees, etc but the short track length makes grading with the dozer blade difficult. I dug out a very large tree, made a mess of the yard. For a slab, definitely hire that out. I have zero bow kills.

 

[Maggot]

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.

Good advice there.

-Do make sure the bar is off the ground. Some use a layer of gravel to ameliorate ground swell.

-Do put heavier slab where the lift column are going.

-DO wet the ground.

-Absolutely make sure they cover it with plastic. Weather's cooling but it still get hot down there. When I lived in Texax I watched a crew pour a slab about your size. It was abut 105 that day and when they finished they just packed up and walked away. I asked the forman "Arent you going to cover it?"...He looked at me like I was nuts and "Ah hell no we dont do that." I stood there and watched for a few minutes and could see it crack. So cover it to keep the moisture in, and if necessary wet it for a couple days. EF may correct me but IIRC it takes 28 days for crete to dry to about 80%

-As the man said, be there and photograph everything. Fucktardery is rampant.

-45K.....nah, keep looking.

 

[LuckyLuke80]

I would recommend looking into what the steel building specs for a slab. They usually want a foundation for the building. Most guys around my neck of the woods incorporate that with the slab. Generally have to make a bolt template for the building posts. If they don’t have anything special designed for it then a mono slab would be fine, but do as others have said and take out the clay. Pouring on top of the clay is almost a guaranteed way to ruin your new slab. I would take the clay/sod out and pour on compacted gravel. I can’t speak to prices in your area, but at my concrete prices and local contractor prices here in north Idaho you would be looking at $24k pretty easily and likely a bit more. 2’ is the absolute max I would go on the rebar, and more like 16”. The new fiberglass bar is pretty awesome stuff. Cheaper, lighter, and stronger than steel. Fiber adds no structural strength so don’t let the supplier or contractor fool you with that. Pour on plastic, and tell them you want super plasticizer (they will know).

 

[XP1K]

in a 40'x64' slab I'd definitely want beams around the perimeter and interior. Especially where I'm at on the gulf coast.

Civil engineers I've worked around in construction say no more than 20' between beams.

 

[TheHorta]

DM me when you’re ready to pour. I have a couple of bodies that need to disappear.

 

[ironpony52]

Oh I forgot to add, I have zero bow kills, can bench 415 at 64, and have placed many yards of concrete. My favorite is laying pavers though.

EDIT: one bow kill a rabbit at 12YO.

 

[MrSmith]

Some good advice posted.

If you don't plan to do any of the installation then hire the same outfit to place the concrete, assemble the building and install the lift, electrical, plumbing .. everything. Then hand you the keys. Make sure you are satisfied with their warranty. Keep any blame for any unlikely failures with one entity. If you do intend to self perform any work make sure to identify exact points where responsibility for results transfer from "them" to "you".

Bow kills: two ducks. Might be able to press a bench if it was aluminum. Been around a lot of concrete, but few slabs. Most time if it was flat and above ground we hired a subcontractor.

Thank you,
MrSmith

 

[hollowoutadime]

Damn that's nice.

 

[ironpony52]

Some good advice posted.

If you don't plan to do any of the installation then hire the same outfit to place the concrete, assemble the building and install the lift, electrical, plumbing .. everything. Then hand you the keys. Make sure you are satisfied with their warranty. Keep any blame for any unlikely failures with one entity. If you do intend to self perform any work make sure to identify exact points where responsibility for results transfer from "them" to "you".

Bow kills: two ducks. Might be able to press a bench if it was aluminum. Been around a lot of concrete, but few slabs. Most time if it was flat and above ground we hired a subcontractor.

Thank you,
MrSmith

Damn, I do not know why but when you posted 2 ducks it made me think of I do have one bow kill a rabbit at about 12 YO in the backyard.................I will have to update my previous post

 

[ironpony52]

Damn that's nice.

This is the outdoor kitchen complete with wood fired pizza oven. This is what happens when I am left unattended......

 

[Modoc]

Plenty of good advice and suggestions above. Not trying to be a downer, but what do the County Building Codes have to say? Unfortunately a lot of those Codes have been driven by bad things happening due to local conditions and construction.

Even just a Consultation with a Reputable Local Structural/Civil Engineer can save you a lot of heartburn down the road.

I had to scrap months of work due to changes in the State Fire Code on a set of building replacements. Thankfully it was still in the plans stage.

Each area has its own challenges from ground, weather, and regulations.

 

[tomcatmv]

Here in central TX all the slabs for houses are post tensioned because of the Texas gumbo clay movement. I'm not a concrete guy, have no bow kills and can only bench about a 115 lb. spread eagled stripper but I would definitely spend a few bucks on a structural/soils engineer. (I do however have 40+ years in commercial mechanical construction, so I've been around this stuff).

 

[vh20]

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.

Why not let one of our own, Erik Cortina, show you how? Plus, he’s in TX where you are. This video is worth the watch.