Concrete strength question...?

Question

I am planning a crazy project and need a professional opinion. I'm in the process of converting my dirt-floor basement into a recroom/bar. I have dug it down 3', poured retaining walls around the base of my foundation, enlarged the outside entrance to 12' wide, 12' long and 10' deep (it will contain a real set of stairs with a toilet under them and a washbowl that I have already plumbed for) and poured 3 10" thick & 10' high walls all around that. Now my next project is to build a form above that entrance and pour a concrete ceiling/roof over that entrance. That ceiling/roof will drop about 1' over the 12' length of it. I will also be boxing out a 4'x8' area in the form to accommodate a steel door that will be special ordered after the concrete sets. My question is, with enough rebar to reinforce it, will a 12'x12' slab of concrete 8" thick have enough strength to bridge that far? I plan on using 5/8" rebar every 1 foot in both directions. Any professional input would be great. Thanx!

Answer 1

Precast Concrete Companies are becoming very common. They would have the span details on file and usually have better pricing than your time invested forming and purchasing material.

Talking with your local Building Inspector is perhaps the best place to start.

These are the online building safety code links I use.

http://www.constructionweblinks.com/Indu...

http://en.wikipedia.org/wiki/Building_co...

http://en.wikipedia.org/wiki/Fire_code

http://www.nfpa.org/aboutthecodes/AboutT...

http://www.ladbs.org/code_enforcement/co...

http://www.iccsafe.org/

http://www.icc-foundation.org/

http://www.dps.state.vt.us/fire/rules.ht...

http://www.ct.gov/dps/cwp/view.asp?a=214...

http://tlo2.tlc.state.tx.us/statutes/hs....

To See Why CONCRETE IS NOT CEMENT!

http://www.brandsconstruction.com/index_...

Answer 2

You are going to need to consult a structural engineer on this question.  The slab will not support its own weight.  You are going to need columns with footings and beam(s).  The engineer will give you the required sizes on each structural member.

This is NOT a DIY project, and no contractor would ever take it on without an approved set of drawings.  Hope this helps.

Answer 3

You need an engineer.  Don't be guessing or get incorect information off of this page.  You don't want to spend a bunch of money just to have something bad happen.  At least call an architect first.