Concrete Quote

[2fst4u_7]

Finally starting to get concrete quotes in for a 36'x48' stick built shop. The company I am leaning towards is quoting my $10,500 for 4" 4000psi with fibermess and with thicker footers where the two post lift is going. The price includes prep with use of the road mix I am having delivered.

My question is, is 4" enough should I go for 5" or 6"? The lift from Greg Smith recommend 4" 3000psi.

And he asked how tall I want the footer wall. Would 6" be good enough?

 

[rattle_snake]

4" is enough for a <10k lift but I would dig out the area where the posts go to 6". thicker only where you need it for basically no extra money.

 

[Diesel Dan]

What I did was 4", 3500psi with 6" under lift in 24"x24" pads.
Skip the fibermesh and use #4 (1/2") rebar on 24" grid pattern.
Don't forget vapor barrier, 10 mil black minimum, IMO.

Can't help with footer walls as that is something I've never done.

Over the years I've had 4 shop floors done ranging from 3,000 PSI with fiber to 3,500 and used welded wire to rebar. The above is what I now use and recommend. Also I have a burnished finish and seal the floor, smoother than some like but works for me.

 

[matt_i]

Footings below the frost line, correct?

If your "road base" includes fines I'd let it settle longer and get wet a few times before you compact it (or your contractor compacts it).

I'd recommend a vapor barrier. 6mil is barely there, I'd also second the 10mil recommendation.

The rebar is the most trouble-free floor imo. Welded wire second. Fiber is a builder's dream. Never set any steel reinforcing and convince the customer its just as good.

I would make sure your slab is a 4" minimum, which means no forming with 2x4s to give a 3-1/2" slab.

I'd also recommend a curing sealer unless you intend to flood it for a week.

6" to 8" above the finished floor is a good place to top the wall. I would pay attention to the details of any man-doors and garage doors as the width between blockouts in the wall forms becomes important as you finish.

 

[Jeep07]

I just got a quote on my driveway area and I was floored.

2200 sq foot of concrete. 3500psi 4" deep. $12k. Second guy was $10.5k. I told both I was wanting them to pour and finish/cut, to them that evidently meant rebar/welded wire mesh/forming/pouring/finishing/cutting. After explaining I was doing all the prep that I just wanted them to come manage the pour and finish the top and cut I got very different prices. All in all they come out to about the cost of material for the labor. ($3-4k of concrete = 3-4k of labor) So now I'm in the 6-8k range for the project.

For the inside of the garage I did 6" 4000 PSI on the 30x40 attached I just had built. However the cost of the concrete was factored into the contractors price so I'm not sure what the real cost was.

 

[Stever60]

The concrete mix is important but as long as it is a good mix is less important than what happens on site. I always ask for no fly ash - I want a straight cement mix. I also ask if the contractor plans on adding water to the mix after they get on site. Concrete strength is directly proportional to the water. You have to have the right amount of water but once you start adding water past the mix design you lose strength. Most contractors for individuals will want to add water on site. The concrete moves and works easier. On an industrial pour or for instance a bridge pour no water is added on site. Probably not every contractor wants to add water on site - but it is something I am sensitive to.

 

[Tdaddy185xlt]

Finally starting to get concrete quotes in for a 36'x48' stick built shop. The company I am leaning towards is quoting my $10,500 for 4" 4000psi with fibermess and with thicker footers where the two post lift is going. The price includes prep with use of the road mix I am having delivered.

My question is, is 4" enough should I go for 5" or 6"? The lift from Greg Smith recommend 4" 3000psi.

And he asked how tall I want the footer wall. Would 6" be good enough?

4" will be fine and 6" pads where your lift will go. 4' grid of 3/8 rod, 4000 psi is all we do, it is not going anyplace. Myself I wouldn't waste any $$ on fiber. Interior concrete doesn't see 90% of what mother nature does to exterior concrete. In this part of the country our charge for this is around $7000 + cost of grade material.

 

[Tdaddy185xlt]

In our parts here concrete companies dont even warranty concrete less then 4000 psi. 3500 is almost a footing mix area here.

 

[Diesel Dan]

In our parts here concrete companies dont even warranty concrete less then 4000 psi. 3500 is almost a footing mix area here.

Yeah, I miss spoke earlier.
Went back and checked and I did use 4,000 PSI on my build.

 

[Moosefire66]

4" will be fine and 6" pads where your lift will go. 4' grid of 3/8 rod, 4000 psi is all we do, it is not going anyplace. Myself I wouldn't waste any $$ on fiber. Interior concrete doesn't see 90% of what mother nature does to exterior concrete. In this part of the country our charge for this is around $7000 + cost of grade material.

Where is "this part of the country" if you don't mind me asking

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[Milton Shaw]

Call the concrete dispatchers and get their recommendations on who to pour and finish. They know who shows up on time with enough people and finishes the jobs right. I don't know what site access is but a pump truck could eliminate several workers and not add that much to the job. It also keeps concrete trucks off property and crushing septic system that was not identified. Go look at other jobs they have done and talk to their customers. I have been very happy with everyone I have hired on this basis. The concrete contractors that have ads in the Yellow Pages have to pay for those ads with extra charges for you, and Yellow pages are not cheap. I have done this for over 40 years on a number of pours and it works. Do use # 4 on 24 inch grid and if there is any part that contacts other concrete jobs drill into that slab and anchor the rebar in to prevent later height movements. And make sure they come back the next morning to cut the control joints and cover/seal to let it cure properly, set up sprinklers on a timer so that it keeps it wet for at least a week.

 

[Tdaddy185xlt]

Where is "this part of the country" if you don't mind me asking

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Mi. Northwest of chithole Flint 10 miles or so

 

[GMCGarage]

What I did was 4", 3500psi with 6" under lift in 24"x24" pads.
Skip the fibermesh and use #4 (1/2") rebar on 24" grid pattern.
Don't forget vapor barrier, 10 mil black minimum, IMO.

Can't help with footer walls as that is something I've never done.

Over the years I've had 4 shop floors done ranging from 3,000 PSI with fiber to 3,500 and used welded wire to rebar. The above is what I now use and recommend. Also I have a burnished finish and seal the floor, smoother than some like but works for me.

What was the reasoning on the #4 @ 24" oc?

 

[bczygan]

What was the reasoning on the #4 @ 24" oc?

Strength in tension.

 

[cmc76]

Just a few thoughts depending on your preferences. First if you do use a fibermesh or stealth fiber. Be certain your finishers have used the product before. And know what you are asking for in a finish. Allot of industrial applications will go past a hard trowel finish and this is trickier with a mesh. Now based on the sizes you gave, to use a grid of #4 bar, with laps you have about .75 ton. You can find your local rebar sales, but here straight bar is about 800-900 a ton. so with tax you are looking at around $700 to buy the bar.
If you were to use a fibermesh, thats around $7 a yard, and using your sizes with some allowance for thickened edge and deeper at your posts i would put your total at about 27 cy. This would put your cost to reinforce at about $200 and that requires no additional install labor.
Given that even if you ordered 3500 psi, its going to likely exceed that anyways. I dont see much point in worrying that point much.
Just be sure your finishers are well versed in whichever you choose. Layout your grids and i personally prefer to sawcut when still green versus a tool joint on an indoor application.

 

[GTFiero]

I'm doing a 30x60' pole building floor with a 48'x24' apron in front of building. Going with 6 bag 4000# mix, 4" thick with wire wielded mesh all, 2" foam under work area (30'x30'), 6" thick 2'x4' pads for 4 post lift in work area, re-rod ties every 2' between all slabs, saw cut expansion joints, floor drain on storage side of building to drain field, 6 mil poly under floor inside building, extra thick edges (8"d x 12" wide) for all apron edge to prevent cracking, thicker edges at building service doors. Also chases for water, gas, electric. All for $11,300.

Fiber was not recommended by contractor.

 

[Moosefire66]

Mi. Northwest of chithole Flint 10 miles or so

Durand?

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[2fst4u_7]

So what is the purpose of vapor barrier? Keep ground moisture from moving into the concrete? Is that for certain regions or good practice everywhere?

 

[ssdave]

I'd put down vapor barrier to keep moisture out of the concrete. Middleton has extremely high ground water, particularly in the summer and fall because of all the flood irrigation. Slabs can get quite damp sometimes if the groundwater is high and no vapor barrier provided.

Have you considered a conventional foundation and stem wall since you're stick framing? It'd cost a bit more, but give you a lot better product than a slab with thickened edge. It also keeps the walls a bit higher above ground and snow moisture.

Winters like last winter can frost heave slab on grade construction, particularly with high ground water conditions. Footings and stem walls add to the cost, all depends on the quality of the building you are trying for, and the importance of the extra cost to your overall budget and objectives. If you're just trying for an equipment shed or farm type shop, slab on grade is sufficient. If you want to have a more improved shop, particularly if it is heated and finished, I'd consider going with a conventional footing and stem wall, frame walls over that, and a floating slab floor.


I just built a 36 x 48 garage here. I opted to go with 24" stem walls to about 30 inches total below grade, with the 12" x 24" footing below the stemwall and that leaves the wood wall with 6 inches above grade. I went 24" to make it easy to use 24" wide forms. I did the work myself, took me 4 days to form, tie rebar, and place the footings and the stem walls. I had about $2000 in the concrete, $200 in rebar and form ties, and $250 in form rental. My bid for the floor slab is similar to yours, I'm at $11,800 for 6" of concrete with rebar 18" o.c.

 

[rburke65]

Well I believe a vapor barrier is a real good idea everywhere. Keeps the concrete from wicking moister up into your floor. Why skip on this....unless you are looking for a damp floor.....

 

[2fst4u_7]

I'd put down vapor barrier to keep moisture out of the concrete. Middleton has extremely high ground water, particularly in the summer and fall because of all the flood irrigation. Slabs can get quite damp sometimes if the groundwater is high and no vapor barrier provided.

Have you considered a conventional foundation and stem wall since you're stick framing? It'd cost a bit more, but give you a lot better product than a slab with thickened edge. It also keeps the walls a bit higher above ground and snow moisture.

Winters like last winter can frost heave slab on grade construction, particularly with high ground water conditions. Footings and stem walls add to the cost, all depends on the quality of the building you are trying for, and the importance of the extra cost to your overall budget and objectives. If you're just trying for an equipment shed or farm type shop, slab on grade is sufficient. If you want to have a more improved shop, particularly if it is heated and finished, I'd consider going with a conventional footing and stem wall, frame walls over that, and a floating slab floor.


I just built a 36 x 48 garage here. I opted to go with 24" stem walls to about 30 inches total below grade, with the 12" x 24" footing below the stemwall and that leaves the wood wall with 6 inches above grade. I went 24" to make it easy to use 24" wide forms. I did the work myself, took me 4 days to form, tie rebar, and place the footings and the stem walls. I had about $2000 in the concrete, $200 in rebar and form ties, and $250 in form rental. My bid for the floor slab is similar to yours, I'm at $11,800 for 6" of concrete with rebar 18" o.c.

I believe that is the direction he quoted me, conventional foundation and stem.

I have attached the quote.

 

[Rock knocker]

I always ask for no fly ash - I want a straight cement mix.

Why? Unless you have a reason based on chemistry, engineering or petrology, there's no reason for that except ignorant micromanaging.

 

[ssdave]

I believe that is the direction he quoted me, conventional foundation and stem.

I have attached the quote.

The quantity of 7 yards quoted is only enough to do the footers the size he quoted and a few inches of stem wall.

So, essentially, a footing and a 8 inch high stem wall. That would put the footings top at about the same as bottom of slab to have 4 inches above slab grade. Not sure what his forms for the slab would be, as the stem wall should naturally form for the footings, except at the doorway.

I'd talk to him and see what he had in mind. If it's not what you expected, now is the time to change, rather than after he starts.

Looking at his costs, he's extremely reasonable. If you don't mind, I'd like to have his contact info, if you'd PM it to me.

I worked as an engineer in Caldwell early in my career, so am somewhat familiar with the area.

 

[matt_i]

The other reason to use a vapor barrier is that you can't (easily) flood the underside of the slab to moist cure it....the water you need to keep the hydration of the concrete continuing...in order to build strength....is leaching into the dry stone or soil below it. Definitely not as easily with the vapor barrier.

 

[jeepntxj]

Why? Unless you have a reason based on chemistry, engineering or petrology, there's no reason for that except ignorant micromanaging.

As a plant manager/batchman for a ready-mix facility, I agree with this 100%. All of our mixes with the exception of a handful, use flyash. Even our industrial mixes. And they all break well over spec from 7 days all the way to 28.

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[sanddan]

Footings below the frost line, correct?

If your "road base" includes fines I'd let it settle longer and get wet a few times before you compact it (or your contractor compacts it).

I'd recommend a vapor barrier. 6mil is barely there, I'd also second the 10mil recommendation.

The rebar is the most trouble-free floor imo. Welded wire second. Fiber is a builder's dream. Never set any steel reinforcing and convince the customer its just as good.

I would make sure your slab is a 4" minimum, which means no forming with 2x4s to give a 3-1/2" slab.

I'd also recommend a curing sealer unless you intend to flood it for a week.

6" to 8" above the finished floor is a good place to top the wall. I would pay attention to the details of any man-doors and garage doors as the width between blockouts in the wall forms becomes important as you finish.

I'm not saying you are wrong but my main shop (36x48) was done using fiber and 20 plus years later I have zero cracks except for expansion joints. I also installed a lift 5 years ago without issue (4" thick concrete).

About 8 years ago I had the RV parking area, which is a 15x36 add on to the original building, done with rebar. That one has large cracks in several places.

The concrete work was done by two different contractors so maybe that had more to do with the cracks than which reinforcement method was used but fiber seemed to work just fine for my shop.

Both areas have similar bases, compacted 3/4" minus crushed rock.

 

[Rock knocker]

As a plant manager/batchman for a ready-mix facility, I agree with this 100%. All of our mixes with the exception of a handful, use flyash. Even our industrial mixes. And they all break well over spec from 7 days all the way to 28.

Yup, properly done, it is a way superior product than concrete ordered without flyash "because".


http://www.cement.org/docs/default-...48-optimizing-the-use-of-fly-ash-concrete.pdf

 

[2fst4u_7]

The quantity of 7 yards quoted is only enough to do the footers the size he quoted and a few inches of stem wall.

So, essentially, a footing and a 8 inch high stem wall. That would put the footings top at about the same as bottom of slab to have 4 inches above slab grade. Not sure what his forms for the slab would be, as the stem wall should naturally form for the footings, except at the doorway.

I'd talk to him and see what he had in mind. If it's not what you expected, now is the time to change, rather than after he starts.

Looking at his costs, he's extremely reasonable. If you don't mind, I'd like to have his contact info, if you'd PM it to me.

I worked as an engineer in Caldwell early in my career, so am somewhat familiar with the area.

PM Sent

 

[GTFiero]

So what is the purpose of vapor barrier? Keep ground moisture from moving into the concrete? Is that for certain regions or good practice everywhere?

Pretty much to keep moisture to a minimum for storing cars, tools and other stuff. Dry floor is a good thing.

 

[Tdaddy185xlt]

Durand?

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Sorry I forgot to say. From Flushing. Durand is south east of us.

 

[joes169]

Just to clear things up a little, as there seems to be far too much confusion over this on the web, microfibers, which are what every one is likely talking about here, are no replacement for steel. They were marketed at replacing steel 20-30 years ago, but even the manufacturer's of the micro fibers quickly pulled back when it quickly became apparent they could not replace steel.


If you look into macro fibers, like "Forta Ferro" for example, it's a whole different ballgame. These style of fiber have been proving themselves in effectively replacing steel, with a few downsides to them.

 

[joes169]

What was the reasoning on the #4 @ 24" oc?

I always wonder the same thing when reading on here as well, especially when I read about #4's on 12-18"centers here. All I can think is that the "compete overkill" mentality run's rampant here on this site. I think most poster's here think changing the oil in their Kia is considered extreme abuse to their concrete or something. If most here saw how well and long un-reinforced, or lightly reinforced, concrete can last first-hand, they might see things in a different light.........

 

[Stever60]

Nothing wrong with fly ash engineering wise. I have been reading articles about 25 years. I work in engineering but have always worked around the coal fired power side. (So personal preference I don't want fly ash in/on my slabs.) Admittedly this is like someone working in a chicken processing plant saying they won't eat chicken.

 

[Diesel Dan]

If most here saw how well and long un-reinforced, or lightly reinforced, concrete can last first-hand, they might see things in a different light.........

I've seen enough (and removed) cracked, seperated un-reinforced slabs in my DIY career to last me.

If some unforeseen settling happens under the slab the rebar will help keep slab integrity, JMO.

 

[cmc76]

If some unforeseen settling happens under the slab the rebar will help keep slab integrity, JMO.[/QUOTE]

- This is absolutely dead on. While shrinkage is a factor in cracking, and mind you this is why we use control joints. I have removed dozens of slabs where the " compacted granular" material beneath had completely eroded leaving a void sometimes over a foot.
Residential applications often use a pea gravel as bedding material. It does not compact well, has very little fines and will generally always lose its compaction.
A properly prepared sub grade is critical.
But back to a topic that has gone back and forth. Reinforcing. As for keeping your slab together, its a horse a piece. I have successfully used integrally mixed products in elevated slabs in excess of 8000 psi.
For the purposes of your home shop, a thickened edge with perimeter bar and a welded mesh in the field will do just fine. Fiber is an option for you as long as your finishers tool it correctly to avoid spawling or delamination of the slab.