# Bidding Concrete Help



## BamBamm5144 (Jul 12, 2008)

I don't need your prices. I don't care about your prices. What I do care about is your knowledge :clap:

As we have been getting more and more into building garages we need to be able to properly estimate the concrete. I want to know it for myself so I don't have to go off what concrete guys tell me since they may be pulling my chain.

I guess my main questions are

1. How many square feet at 4" deep should I get out of one cubic yard of the concrete?

2. How much reinforcement is necessary? Rebar every foot? Something else every foot?

3. How much reinforcement is necessary along the perimeter?

Anything else?

Thanks guys.


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## Tscarborough (Feb 25, 2006)

1) 84
2) Depends
3) Depends


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## CanCritter (Feb 9, 2010)

doin concrete is not for the faint of heart....when something gos wrong is generaly costly to fix espeacialy when cracking starts


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## greg24k (May 19, 2007)

Length x Width x Depth / 27 x 1.05 (If you want to add for waste or make up for low spots,etc) = Concrete Needed 

Usually when you come up with 4.44 yards, you will order 5, that will cover your extras... much cheaper to order a little extra, then be short.

Re-bar, wire-mash etc in most cases it's a design requirement, the plan will have specification for placement, re-bar size, etc also the required spacing, or a contractor will take extra precaution in the field if he feels it should be installed because of the soil condition or high traffic area,etc.


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## BamBamm5144 (Jul 12, 2008)

Tscarborough said:


> 1) 84
> 2) Depends
> 3) Depends


Hopefully you don't do concrete yourself.



CanCritter said:


> doin concrete is not for the faint of heart....when something gos wrong is generaly costly to fix espeacialy when cracking starts


Huh? It's concrete. Nothing should go wrong. I am not talking about concrete for huge structures that are millions of dollars. I am talking concrete for Garages and an occasional driveway when the customer wants it all done at once.

My reason for asking is that so I fully know what my subcontractor is offering. I had one that did good work but didn't know what good morals were. He thought that he could go behind my back to re do the customers driveway that we are currently building a garage for. Thus meaning, I have to bring in new guys and try them out.


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## donerightwyo (Oct 10, 2011)

Really only a few things to know about concrete.
It's grey, it's heavy, it's gonna get hard, and it's gonna crack.


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## TheItalian204 (Jun 1, 2011)

Well Bam,concrete is portugese trait,but I will bite.

1. You already have answer.

2. Any pour bigger than 5x5 that will carry any type of weight requires re-bar...even if two short sticks.

Also look into expansion and control joints as well as brush finish reduces risk of cracking.


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## dom-mas (Nov 26, 2011)

I can only help with #1
3x3x3=27/0.333333333=81-waste= +/- 75sqft of 4" concrete/yd.

I'll tell you what about reinforcement on a floor. I've never poured one but I've been working while many have been poured and i don't ever remember seeing steel in them. Maybe I'm wrong tho and they used 4 square. What do I know tho, my last name ends in a vowel but i don't speaka no concreeta


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## fjn (Aug 17, 2011)

*concrete*

Another thing about concrete, a good concrete job costs alot of money--------a bad one costs even more.


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## 6stringmason (May 20, 2005)

rebar placement is critical from everything I've read and experienced. Its got to be positioned just right in your pour or you may as well not even put it in at all.


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## fjn (Aug 17, 2011)

*re-bar*

One thing iwas taught about re-bar,get it to do it's thing as soon as possible. Example drive ways and garage floors should be 5in. not 4in. If re bar is in bottom third it goes into tension quickly. If in upper third it goes into compression quickly (to resist heaving) in center of pour most useless place for it ,place of almost 0 movement. I have been placing #3 bars on 18in grid for years. I swear by it cost about as 6x6 10 ga. and ends up where you placed it and where you need it. The wire gets stomped to bottom or jerked to high (ever see checker board rust stains on drives) that is how it happens


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## Tscarborough (Feb 25, 2006)

Edited.

Edited again.

Garage:
#4 bar, 12" O.C. mat, 4x #4 in 12x18 perimeter beam and at 20' OC, #3 stirrups 24" O.C.

Driveway:
6x6 6/6 mat, 2x #4 in 12x12 perimeter beam, #3 stirrups 24" O.C.

This is for my location only, your mileage will vary. It is not a matter of knowledge, Bambam, it is a matter of your question being too broad. You have to either learn to calculate it or be willing to guestimate it on the side of caution (like above), but most importantly, it really is job and jobsite specific.


(84 above is wrong, I used 28 CuFt not 27. Doh!)


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## smeagol (May 13, 2008)

2.35$ a sq ft here at 4" here.


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## Tscarborough (Feb 25, 2006)

That will buy you the concrete and gatorade here.


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## txgencon (Jan 4, 2011)

I read a lot of comments here where it seems people build garages on what I would consider flatwork. Even on a 11' x 18' "accessory" building (popular here because the restrictions really don't kick in until you get over 200 sq ft) everyone generally makes a beam around the perimeter to 12"-16" inches thick and 12" wide. The minimum ready mix delivery is 4 cu yds. This usually resulted in about 1/2 yd left over - enough that they won't do their washout on your job.


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## BamBamm5144 (Jul 12, 2008)

Thanks.

As I said, this isn't an in house thing. I will be finding the right concrete guys to do all my concrete work. I need to make sure he isn't telling me that I'll need rebar support every 3" or something crazy.


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## mrcharles (Sep 27, 2011)

txgencon said:


> I read a lot of comments here where it seems people build garages on what I would consider flatwork. Even on a 11' x 18' "accessory" building (popular here because the restrictions really don't kick in until you get over 200 sq ft) everyone generally makes a beam around the perimeter to 12"-16" inches thick and 12" wide. The minimum ready mix delivery is 4 cu yds. This usually resulted in about 1/2 yd left over - enough that they won't do their washout on your job.




That is called a monolithic slab foundation. The advantages of this are being able to pour everything in one pour.


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## 6stringmason (May 20, 2005)

Where are you located in WI?


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## txgencon (Jan 4, 2011)

mrcharles said:


> That is called a monolithic slab foundation. The advantages of this are being able to pour everything in one pour.


Yeah, I know what it's called the way it is done here.

So you're saying they put something under these "caps" when it's for a garage or accessory building?

The largest monolothic slab I've poured by myself is 18'x22'.


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## JBM (Mar 31, 2011)

Everyone puts wire in the floors here, never seen anyone use rebar, in a garage floor, and ive watched a couple hundred guys pour floors over the years.


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## oktex56 (Dec 30, 2011)

Hi,

In Wisconsin you should have a footer around perimeter reinforced with rebar probably 36" deep or deeper depending on code. (Use rebar that is epoxy coated to eliminate rust.)

Slab should be at least 4000 psi mud (denser and stronger as freeze thaw is the enemy) with either fiber reinforcement or mesh on chairs to keep it mid-slab. (Fiber in mix was developed first for hardened missile silos...lots of conjecture as to which is best, wire or fiber.)

Do not allow extra water! Finishers are notorious for doing this and it weakens the mix...howsomeever...a gallon or two on extra dry slump is ok.

Retarders or plasticisers are preferable if it's a super hot day.

Mesh just holds cracking together not allowing it to crack too wide.

If you use metal key joints it is best at proper spacing. This controls the cracks and you have to work within the limits of your material. (typical garage is 20 x 20 so make 4 equal sections...they also come with rubber tops which can be removed and a self leveling urethane caulk applied.

Drill slab into home (if attached) with sleeved rods to stop structures from settling at different rates.

Driveway does not need a footer but make sure you get consistent depth and design joints no larger than 12 x 12...some say 10 x 10.

Concrete has been around so long and there is so much information about how and why it works and fails. 

Design each pour within the limits of what it will and will not do and you will all but eliminate call backs and any potential issues.

http://www.concrete.org/Technical/CKC/technical_questions.htm

Hope this helps.

Steve:thumbup:


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## fjn (Aug 17, 2011)

*steel*

Not to appear contrary however, it would be interesting who is making the steel for the 5 yr. old rust buckets. Bethlehem steel now Arcelormittal steel (largest steel producer in world) developed the galvalume coating system. I believe either/or both G.M.& Chrysler awarded them the prestigous award as sole steel supplier. Reason being, flawless surface i.e.no waves,and ability for coating to stay bonded in stamping method. The upshot to consumer,superior paint adhesion,long rust resistance. I do not know where the rust buckets get their steel. It probably does not come from Arcelormittal. Possibly import duties may play a role?


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## jomama (Oct 25, 2008)

oktex56 said:


> Hi,
> 
> In Wisconsin you should have a footer around perimeter reinforced with rebar probably 36" deep or deeper depending on code. (Use rebar that is epoxy coated to eliminate rust.)


Detached garages don't need to be on a frost protected foundation here in WI, floating slabs are completely permissable by code, and I'd say 90% of garage are as such............


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## oktex56 (Dec 30, 2011)

jomama said:


> Detached garages don't need to be on a frost protected foundation here in WI, floating slabs are completely permissable by code, and I'd say 90% of garage are as such............


I live in STL and we did quite a few sunrooms which are of course attached to homes. Even existing slabs were dug out and footers poured and inspected prior to pour. WI does not require footers even if attached?

Wow! IMHO that is wrong regardless of where you live. I dunno, sometimes best practice supercedes code. I know there has to be heave, due to freezing...

Down south in the land of no basements and slab on grade they still do somewhat of a monolithic footer.

Steve:thumbup:


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## fjn (Aug 17, 2011)

*floor*

Never was a fan of so called "floating slabs",never poured one that i put my name on.When you put a pencil to the amount of steel needed in that application,so you can sleep at night i take a pass on those jobs. A spread footing and stemwall,with a a floor poured as in my previous post woked for me every time. Do not put alot of stock in monolithic pours with all their do-dads,stirrup etc. I firmly believe floors and drives should be a "real 5 in.min. Not the so called 4 in.which translates on many jobs to 3.5 in. (2X4 ON EDGE). Part of the reason for 5 in.is you get to put steel at 2 in off bottom and still have enough concrete coverage to protect non coated steel. I care not if code allows floating slabs,i'am not their guy then. A rule that has served me well all these years is, you live and die by your reputation and your only as good as your last job.


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## jomama (Oct 25, 2008)

oktex56 said:


> I live in STL and we did quite a few sunrooms which are of course attached to homes. Even existing slabs were dug out and footers poured and inspected prior to pour.* WI does not require footers even if attached?*


No, you ABSOLUTELY need to install frost footings (48" deep minimum) here IF it's attached. BUT, if it's detached, a floating slab will suffice.....



fjn said:


> Never was a fan of so called "floating slabs",never poured one that i put my name on.When you put a pencil to the amount of steel needed in that application,so you can sleep at night i take a pass on those jobs. A spread footing and stemwall,with a a floor poured as in my previous post woked for me every time. Do not put alot of stock in monolithic pours with all their do-dads,stirrup etc. I firmly believe floors and drives should be a "real 5 in.min. Not the so called 4 in.which translates on many jobs to 3.5 in. (2X4 ON EDGE). Part of the reason for 5 in.is you get to put steel at 2 in off bottom and still have enough concrete coverage to protect non coated steel. I care not if code allows floating slabs,i'am not their guy then. A rule that has served me well all these years is, you live and die by your reputation and your only as good as your last job.



With all due respect, that's nothing more than your own opine, and although I'm not a huge fan of them myself, it's hard to argue with the factual evidence that they work in practice. There's undoubtedly 100's of thousands of grade-beam slabs here that will long outlast the lightweight wood garage that sit's on top of them......

We certainly install full frost protected foundations for detached garages here, but it costs far more and it's typically reserved for sites that have a small footprint with a large garage, sites that would require a huge amount of gravel to be brought in and the landscape has very little room for elevation corrections, or just an ignorant HO that will not open their mind to something "non-traditional".....

If I had to guess, I'd say 80-90% of detached garages here are built on a floating slab........


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