Concrete questions

COLTIMPALA

COLTIMPALA

Yo homie... is that my briefcase?
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So I'm pretty uneducated in this department and only really know the basics and thought I'd ask here.

I'm planning to have a 24x20 concrete pad poured, and then add two courses of cinder block, and set a metal carport on top of it. Then frame in the sides and basically have an enclosed shop. I won't get into why I'm going this route over a full on metal building.

My questions are these; what should I expect to spend on a 24'x20' concrete pad, say 5" thick? Meaning having a crew come out and do this while I watch and drink beer.

Secondly, to run two courses of block and set the building on it as I described, do I need footers?
 
COLTIMPALA said:
So I'm pretty uneducated in this department and only really know the basics and thought I'd ask here.

I'm planning to have a 24x20 concrete pad poured, and then add two courses of cinder block, and set a metal carport on top of it. Then frame in the sides and basically have an enclosed shop. I won't get into why I'm going this route over a full on metal building.

My questions are these; what should I expect to spend on a 24'x20' concrete pad, say 5" thick? Meaning having a crew come out and do this while I watch and drink beer.

Secondly, to run two courses of block and set the building on it as I described, do I need footers?
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As of about 18 months ago it was $125 per square foot poured and $125 per sq ft to finish.
 
amnesia said:
As of about 18 months ago it was $125 per square foot poured and $125 per sq ft to finish.
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Per sq ft? At those prices a 20'x24' pad would be 480 sq feet and at $250 / sq-ft to poor and then finish that would be $120,000.

Off hand, I was thinking in the couple thousand dollar range. Home advisor, which was just the first hit for current concrete prices: https://www.homeadvisor.com/cost/outdoor-living/deliver-concrete/ says on average $125 per cubic yard. To get the cubic yards: 480 sq-ft * 5/12 (5" is 5/12ths of a foot) giving us 200 cubic feet. Since there are 27 cubic feet in a cubic yard, this works out to be roughly 7.5 cubic yards, which would be in the $1,000 - $1,250 range. Double that for finished concrete and call it $2,500.
 
COLTIMPALA said:
Meaning they do everything and I watch?
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That's correct. The schedule the trucks which normally come from the same place. Then they broom finish it. 5 inch thick/ 3k psi
 
noway2 said:
Per sq ft? At those prices a 20'x24' pad would be 480 sq feet and at $250 / sq-ft to poor and then finish that would be $120,000.

Off hand, I was thinking in the couple thousand dollar range. Home advisor, which was just the first hit for current concrete prices: https://www.homeadvisor.com/cost/outdoor-living/deliver-concrete/ says on average $125 per cubic yard. To get the cubic yards: 480 sq-ft * 5/12 (5" is 5/12ths of a foot) giving us 200 cubic feet. Since there are 27 cubic feet in a cubic yard, this works out to be roughly 7.5 cubic yards, which would be in the $1,000 - $1,250 range. Double that for finished concrete and call it $2,500.
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I just did that math and was thinking the exact same thing.
 
noway2 said:
Per sq ft? At those prices a 20'x24' pad would be 480 sq feet and at $250 / sq-ft to poor and then finish that would be $120,000.

Off hand, I was thinking in the couple thousand dollar range. Home advisor, which was just the first hit for current concrete prices: https://www.homeadvisor.com/cost/outdoor-living/deliver-concrete/ says on average $125 per cubic yard. To get the cubic yards: 480 sq-ft * 5/12 (5" is 5/12ths of a foot) giving us 200 cubic feet. Since there are 27 cubic feet in a cubic yard, this works out to be roughly 7.5 cubic yards, which would be in the $1,000 - $1,250 range. Double that for finished concrete and call it $2,500.
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sorry square yard is what I meant.
 
Exact prices from 18 months ago for what I had poured and finished

6 yards 12x35 - $1700

13 yards 30x35 $3500

8 yards 14x42 $2200
 
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I just paid $8k for 30x40x6" 4k psi, fiber re-enforced with pump truck.I purchased the form boards and metal mat. separate. Prices have only gone up and good luck finding a concrete company that will bring a truck before noon. I found that most concrete suppliers are slammed and not gonna deal with the small guys.
 
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At 5” thick all the way that’ll be right at 8 yards. Contractor rates I would pay $210 per yard for the concrete and labor combined. As a homeowner if you can find someone to do it be prepared to pay $250-$350 per yard.
 
My guess is you will need at minimum a turn down slab per code or if the carport manufacturer requires/recommends it. Extra work and concrete will up the price. 5" will not cut it.
 
Notn
REELDOC said:
My guess is you will need at minimum a turn down slab per code or if the carport manufacturer requires/recommends it. Extra work and concrete will up the price. 5" will not cut it.
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Code irrelevant, this is an agricultural shop/building without power.
 
Ok.

Redimix in the RDU area is currently running around 150 per yard for a 3000 psi mix. Figure 250-300 per yard total for labor and mud.

For a shop, be sure to have a good vapor barrier put under the concrete.

To minimize cracking, specify in advance that you want a 3.5” - 4.5” slump at the site and do not let them add water to the mix.

5” is plenty for most shops, unless you will be running very heavy forklifts or loaded trucks over it.

Yes re footers for the perimeter.

subgrade prep is important. Remove all topsoil and any organic material. Build back up with compacted abc or gravel.

I prefer steel over fiber reinforcement . You want the steel about 2” from the bottom of the slab. Steel at the top of the slab won’t help much.

don’t let the slab freeze for the first 3 days after pouring. Use insulated blankets if needed.
 
You will need a footing for that for sure.

ETA and if you are doing the blocks to account for grade changes then you will want to waterproof the outside of the block where its below grade.
 
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Scsmith42 said:
Ok.

Redimix in the RDU area is currently running around 150 per yard for a 3000 psi mix. Figure 250-300 per yard total for labor and mud.

For a shop, be sure to have a good vapor barrier put under the concrete.

To minimize cracking, specify in advance that you want a 3.5” - 4.5” slump at the site and do not let them add water to the mix.

5” is plenty for most shops, unless you will be running very heavy forklifts or loaded trucks over it.

Yes re footers for the perimeter.

subgrade prep is important. Remove all topsoil and any organic material. Build back up with compacted abc or gravel.

I prefer steel over fiber reinforcement . You want the steel about 2” from the bottom of the slab. Steel at the top of the slab won’t help much.

don’t let the slab freeze for the first 3 days after pouring. Use insulated blankets if needed.
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Thank you! This is exactly the type of answer I was hoping to get.
 
Catfish said:
You will need a footing for that for sure.

ETA and if you are doing the blocks to account for grade changes then you will want to waterproof the outside of the block where its below grade.
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Blocks aren't to account for the grade, rather to bring the wall up higher and I just like the look batter than metal all the way to the slab.
 
$8 to $10 per square foot would be a fair price if you can find someone to do a small job like that for that. Scsmith’s advice regarding sub grade prep is crucial if you want your slab to last. If the block is load bearing then yes on the footing or just thicken the edge of your slab where your block is going.

ETA: $15 per sf wouldn’t surprise me for a small project like that.
 
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Scsmith42 said:
Ok.

Redimix in the RDU area is currently running around 150 per yard for a 3000 psi mix. Figure 250-300 per yard total for labor and mud.

For a shop, be sure to have a good vapor barrier put under the concrete.

To minimize cracking, specify in advance that you want a 3.5” - 4.5” slump at the site and do not let them add water to the mix.

5” is plenty for most shops, unless you will be running very heavy forklifts or loaded trucks over it.

Yes re footers for the perimeter.

subgrade prep is important. Remove all topsoil and any organic material. Build back up with compacted abc or gravel.

I prefer steel over fiber reinforcement . You want the steel about 2” from the bottom of the slab. Steel at the top of the slab won’t help much.

don’t let the slab freeze for the first 3 days after pouring. Use insulated blankets if needed.
Click to expand...
This is all good advice. Vapor barrier and a good base course.

Concrete loves to crack. Especially when poured in a large slab. Steel or fiber will help limit the cracking and control crack widths.
 
Can you combine steel rebar and fiber to create a more crack resistant floor?
 
I am more familiar with bridge decks. But I don’t see why you couldn’t. Rebar only helps once the concrete cracks by going in to tension and controlling deflection and still works after a deep crack. I think fiber would help more earlier on.
 
Make sure they use a vapor barrier , grade the area well and put a layer of crushed limestone as base. Make sure they saw joints in it when finished.
Since it is going to be a shop you may want a drain in the floor
 
Where are you located? I know some smaller guys that are just good ole boys and dont charge an arm and leg but do a terrific job
One guy, a year or two younger than me, did stuff for my father (twice), my pad, and then my neighbor liked what I had and got an addition to his driveway done.
Pretty quick, I got three quotes and his was the lowest, too.
 
ronn47 said:
Can you combine steel rebar and fiber to create a more crack resistant floor?
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Sure.

The three largest contributor’s to concrete cracking are: Poor sub grade preparation, poorly installed/designed expansion joints and too much water in the mix. Concrete shrinkage during drying is directly proportional to the amount of water in the mix. A low slump mix may not be the installers friend, but it sure is for the owner.
 
REELDOC said:
My guess is you will need at minimum a turn down slab per code or if the carport manufacturer requires/recommends it. Extra work and concrete will up the price. 5" will not cut it.
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most require 12"×12" for anchoring in concrete.
 
One thing to possibly consider if one is pouring a slab is treating the area for termites first. I know that any “permitted” job required that. It was cheap too. Doubt it’s as big of an issue for metal buildings, but might be worth looking into at least.
 
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