Digging foundation beams prior to setting forms?

[Chuck K.]

I should have stated that I am putting up a 40'W x 60'D metal building/shop with either 16 or 18 foot eves. Along one of the 60 walls will be a 24 wide lean to. The overall slab will be 64 x 60.

Here is what it will look like, or so I hope



If I dig and pour the footings/beams flush with the ground first then set forms, bring in sand rebar etc. would the slab adhere properly to the footings or would one want the slab to float on beams? A monolithic pour means footing slab all one continuous pour right? This type of prep and pour would seem to be more difficult. I do plan on cross beams as the engineer suggested/

I hope KHD did not mind of me showing his pic. it is what I had in mind;




I found a neat forum on cement, slump, paste, fly ash, ag mix, water reducer, etc. etc.
There is a lot more to concrete then I ever expected. I want to do it right if I can. I did a rough calculation and came with about 133 yards of concrete would be used in beams and slab. I do not want to waste 10 -15,000 dollars in concrete and materials if I screw up.. Maybe with this kind of money at stake I should leave it to a professional but I like to learn and have the satisfaction of doing it myself.

I have a civil eng. Neighbor who is drawing up plans required for the city permit he indicated he would like to go down to virgin soil meaning beams would be ~2 deep and 18 wide (width of my B/H bucket). Purchasing a smaller 12-14 bucket may be justified to save money on concrete? A friend offered to have his engineer perform a soil density test, a backscatter test was done and compaction came back greater than 95%. The fellow who has to fill out all the documentation took an unexpected leave of absence and do not know when he is coming back. Should have know it was too good to be true to get this for free so I may have to pay someone in order get the project going again.

Thanks for help and patience. Chuck.

 

[EddieWalker]

Chuck,

Sounds like you have a solid plan and design. Metal buildings have different requirments then wood ones for footings on a foundation, and it's nice to see you addressing that.

From what you have said, you don't have any experience pouring concrete. This in NOT the time to learn. Concrete is miserable,difficult and unforgiving.

Make one small mistake, and you live with it forever. Amatures make hundreds of mistakes on finishing it off. YOU WILL MESS IT UP if you do it yourself. I have some experience with pouring pads and will do 1 and 2 yards pours on my own without any problems, but after that, it gets to be too much to do without help. On a pour your size, you will need a crew of half a dozen or more!!!

If it was me, I'd contact a cement contractor that you trust and is highly recomeneded. Again, imagine what you will feel like after spending all that money and you end up with an uneven surface that looks like cr@p?

When I need a large pad poured, I like to do all the prep work myself. Level the pad, set the forms, dig the footings and install the utilities. That's all pretty basic work and something that jaut takes a little time and allot of measureing. It's not really something that you need to hire out if you can read a plan and take accurate measurements.

Then I call up my concrete guy and he comes over to inspect what I've done and get an idea of what he'll need to do the actual pour. He charges me $500 for the labor to do the pour and his cost for the concrete. He'll bring a crew of workers who all know what they are doing, along with all the tools for spreading and smoothing the concrete. He'll arrange the delivery times on the cement trucks and have it so they arrive when he's ready for them and have them unloaded and spread in just a few minutes.

It's very dificult to spread concrete over a large area and get it level. It's even harder to do this AND get a perfect finish on it. It's impossible to do this your first time and it's also impossible to do this without an experienced crew. I'm a contractor here in Texas. I make money on what I do, not what I hire out, but there is no way that I can do what they do.

Seriously, don't try to pour this yourself. YOU WILL REGRET IT.

Eddie

 

[rural2]

I can only assume that the engineering is correct. I learned a long time ago not to second guess competent Engineers, Architects and Designers. However your footings and grade beams @ 2' thick are pretty thick for the structure size. So I can only assume your soil conditions warrant this.
Yes, "monolithic" with reference to concrete placement means no cold joints thus dictating a single pour. I would suggest consulting whoever is doing your structural engineering as to whether or not you even have an option for the placement. Actually a monolithic pour, in your case, may be quicker, easier and cheaper since less form work is involved and the concrete crew will only mobilize one time.
In my experience 98% compaction is minimum. 95% may sound or seem adequate, however I can tell you I personally have not knowingly authorized concrete placement on less than a 98% + compacted sub grade. I have had to go down to native soils may times to make it happen. A possible option may be to simply excavate to native, then backfill with a "lean" cement mix. Again consult your structural engineer and crunch the $$$ numbers to determine if this would make financial sense???
From reading your second post I get the impression you already know what you need to do as far as tackling this project yourself.

 

[firemanpat2910]

I agree with eddie. this is not the project to learn concrete on. I did a walk way at my parents house that was 3' x 20 never again. I wont roof a house or pour concrete. some things are best left to the young bucks that know what they are doing.

 

[BB_TX]

I also agree with Eddie. I watched them pour my 30'x40'. There were 5 or 6 guys and they worked their butts off while the trucks were pouring and some time afterward getting it smooth and level. Then they spent probably another hour or more floating it and finishing it. They were young, but they were beat by the time they finished. And they do that every day!
Also my metal building plan called for a drip ledge around the perimeter of the foundation. Don't know if you plan on that or not.