I want to pour a 24' x 40' 6" thick (new construction) garage floor to build on. The soil is well compacted. 3/8" rebar tied @ 24" spacing, raised 2". Footer 14" wide by 12" deep with 3/8 " rebar. What I want to do is pour the footer and the slab in one pour. Will this create a problem with expansion and cracking? What disadvantages are there to this method of pouring concrete?

 

It appears you have a structural slab and not a floating slab. You will definitely need a lot of help to place and finish. You only have 20 yards or so of concrete. If you are not experienced with placing and finishing it would be good to break the slab into 2 pours (24 x 20).

It sounds like you are thinking that it is neccessary to pour the footing and the slab at different times. Whoever told you what size footing, rebar size and spacing should be able to give you some advice.

Will you have control joints or very deep sawed joints?

If not, you will have cracks, no matter what you do.

Dick

 

Hi Dick, No one told me how to do this project; I just used what common sense I had to figure what would work for what I wanted. The footer dimensions are my own figuring and I wanted to pour the slab and footers at the same time. I plan on having heavy loads on the concrete from time to time. I have a problem with concrete delivery and thought when the weather is right, I can have three or four trucks deliver at once and make the pour in one day. Labor isn't a problem. I asked the questions to get a feel for direction. I can't afford a professional crew to come in and do it, so I'm trying to tackle the job myself. The information you have provided is very helpful and anything I can learn with help me succeed.

Al
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Al-

Common sense is great, but you need some help and input from others. You do not attack a job like this by yourself - you need help!

First, you have to plan the job so you do do it with the resources available. These include design, details, materials and manpower.

You have taken it upon yourself to determine the thickness and reinforcement. You wish to get local assistance on common practices.

You have to provide for the ultimate shrinkage of concrete by providing control joints (deeply sawed or tooled). These can provide an opportunity to break up the construction process.

Concrete is permanent and is not like wood. You cannot change, cut, whittle, shim and alter it after you have placed it. Because of this, it must be placed correctly. You also have to make sure your have the correct anchor bolts (and nuts available for carpenters) in the correct place to avoid the studs to be installed later.

You need someone to help that has experience in placing and finishing concrete. After that, you can get all the "grunts" (friends with an interest in getting the concrete in place) to move the concrete and get it reasonably level (screeded) under the supervision of someone with experience. Look to your supplier for references or just look at good projects and approach someone that seems to be efficient (not just look good).

A good ready-mix supplier will not blindly send 3 or 4 trucks to a job at once. Check with your supplier for recommendations on someone to assist you in running the job. Depending on the distance and logistics a two day job may be better than a one day.

Pouring (or more properly, placing) the concrete is one thing. It must be finished and cured properly. If the surface is not level (or sloped as designed) and not to the desired finish (troweled, broomed, etc.) you will never be satisified.

Find some help and don't try to be too logical and do it yourself. You seem to know what you want, but it takes some experienced assistance to get it.

Dick

 

Thanks for the advice Dick, but I live so far in the country that there is no one that I know of can provide guidence. I have looked at other projects on the internet and picked up what I could. I'll just have to settle with what ever turns out. I'll read some more and look at other projects before I do this. So wish me luck. Live and learn as they say. Thanks again. Al