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Posted: 4/20/2016 1:46:41 AM EDT
Say a guy wants to build a concrete block wall, reinforced with rebar and concrete filled cells.  Basically want to build two walls that attach to existing walls to form a box/small room.  The only catch is this 8' wall will be built on an existing concrete slab.  I know setting the new heavy wall without landing on a footer is a no-no.  

My question, is there an alternative to a footing?  Can I pour a wide reinforced beam on top of the existing slab to help carry the weight of the narrow wall, and construct the wall on top of that beam?

There is no way to get a sign off to cut the existing slab, demo, and pour a footing.  But I might get the green light to form some sort of beam.

Link Posted: 4/20/2016 6:48:10 AM EDT
I don't know about where you live, but in my area, if an engineer stamps it, you can build it, as long as other codes are followed.   That would cost around $500 to have engineered here (North GA).  I would have it engineered, if your wall collapses or destroys your slab, you will not be ahead in savings.  I don't see why you can't cut out the section for the footer and pour a 18" wide, 12" deep footer with 2 #4 rebar in it.
Link Posted: 4/21/2016 1:52:08 AM EDT
Well, when I mean sign off, I meant the wife would shoot me if I took a demo saw to her porcelain tile

And I cannot cut the slab, since there are embedded heating tubes for hydronic heating that keep my tootsies warm when I am bailing an Obama on the throne in the winter.  And I like having warm tootsies.  

I was hoping to sacrifice some interior space with the beam, allowing me to build my little wall for my little block room...
Link Posted: 4/21/2016 7:20:26 PM EDT
I am NOT an engineer, but I would think they would order something like a 48" wide reinforced beam poured on top of your slab.  Do you know if there is any rebar in the slab?  If you're lucky there is. But likely not.  The bearing capacity of your soil?  These are things the engineer will ask. Call a concrete contractor in your area and see who they use for engineering, get a price for the design, do not skip this and bubba it.  It will probably be a lot cheaper to do a proper footing and replace her tile than to mess around with a grade beam.
Link Posted: 4/21/2016 8:05:34 PM EDT
In my own home I might give it a try if it was important to me.  A slab on compacted earth/gravel is very strong and using lintel block for a first course would be helpful.   What's difficult is not knowing if the builder did a good job of prepping the site for a slab...  We put a elevator shaft in a 50 year old college building years ago and when we cut the old slab for the elevator pit there was a void between the slab and the soil.  In some places as much as 3", but the slab surface looked OK, surprised me.

You're in a bad position because of the hydronic lines.
Link Posted: 4/23/2016 9:55:39 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By billhw1:

You're in a bad position because of the hydronic lines.
View Quote

I think this is the final answer.  I knew it deep down, just did not want to admit it.  

Thanks to all for the comments and the input!  
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