We currently have a 18 yr old "flagstone/sandstone" patio with concrete between that is rough, uneven, and now deteriorating. The base was well prepped with tamped rock and sand, but the moisture has gotten between the rocks and they are breaking down.

One Contractor said we could leave this, cover with a sand leveling and then lay another stamped concrete on the top.

Would this be successful, or should this base be all lifted and start over? (Its a big job to get this all out so hoping the consensus is that it will lay over successfully without cracking.)

Give me your feedback if you have knowledge of this construction.