I own a 1000 sq foot home in New Hampshire. It was built in 1963 on a concrete slab with no footings or frost walls. We are about to add 896sqft off the back of the house. NH now requires slab on grade's to have 4' frost walls. After speaking to a builder we are concerned about how to join the new slab to the old one and not cause cracking and other problems...

We install rebar 1/2 thick into the existing slab and let them span out into the new slab

Our add on room slab is separating from the existing house and we want to install glued down hard wood flooringover the whole area. What is the best way to bond both slabs together?

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Originally Posted by flooring

Our add on room slab is separating from the existing house and we want to install glued down hard wood flooringover the whole area. What is the best way to bond both slabs together?

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A bit too late now. About the only thing to do is cut the slab, install bolted steel plates across the joint, fill in with sand mix and hope for the best . They should have tied the slabs with rebar before pouring the addition.