URGENT!!

[Drake]

Ok, I'm pouring a concrete slab on top of a sistern tank. The reaons for this is that I'm putting my garage there and I will have 2 vehicles + extra weight. Basically what i need to know is the dimensions of the concrete, (I think it should be 8" thick) and the placing and size of the rebar, (I think it should be 1/2" rebar and one placing of it 2" from the top and one 2" from the bottom). Oh, and I also must know if the rebar should be placed 10" apart. Someone please HELP me!

[doyle]

Is the sistern now defunct? Why not just have it filled in with gravel and not worry about it caving in? How big is the sistern? If you fill it in, you could go with thinner concrete wouldn't you think?

[mjpliv]

I may start to sound like a broken record but in any situation that requires the design of a structural concrete component - use an engineer. There are so many factors involved that the most you are going to get from this forum is a good guess.

If you do not require an official engineer's stamp on your drawing for the local building authorities then the fees for design services by an engineer can be quite reasonable. When the official stamp is used, then the fee will probably increase dramaticaly because the engineer who signs that stamp assumes responsibilty for that componet's structural integrity - for the life of that component.

In most case the stamp will not be required. Having the slab designed by a professional engineer not only protects you and others from personal injury due to structural failure but also helps protect your investment by not building a sub-standard structure.

You may even save a few bucks by using an engineer because you could use less concrete and less bar. Remember, you are paying by the pound for steel.