concrete over existing slab

[MC]

I have an attached garage that also is extended out about 10 addtaion feet behind the house. I would like to extend addtitional 6 feet.

I would also like to have the original extra 10 feet and addtional 6 feet to the floor level of the rest of the house, Currenlty about a 5 inch step down into the garage.

My plan is to make this into an office and other living space.

My question is, would it be OK to pour over existing concrete.

I would make the addtional new slab as thick as the current slab plus what I add to the original.

If this would be OK to do, Should I also add wire to the new concrete over hte old being would be 5 inches think ?

Thanks, MC

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In general this should be possible. The old concrete should be etched or coated with a bonding agent to ensure a good attach but even if not, 5" on top won't shift. Use rebar or remesh mats to minimize cracking as usual and it should go fine. The additional 6' extension should have sufficient compacted base rock so it dosen't try to split off from the main slab. May want to use extra rebar in the transition zone to prevent or at least control any crack that may develop at the joint.

The unanswered question is "can the land beneith the slab support the additional load?" In most cases it will but if you live on a slope, have soft or unstable ground conditions or the like, you should consult an engineer. If you consult a contractor, they should also be knowledgable (but you probably know that). They can tell you how much base rock you will need under the new section for stability based on your conditions.

You likly will need a building permit because you are adding living space. The answer will be plainly clear when you try for approval. The issue here is "will the additional 6' of slab put you over the setback required by the city" (i.e. too close to property line). In my city, you can usually get away with calling an inspector directly and asking what they will be looking for. You should also call the planning/permitting dept in your city hall first.