Look, I’m trying to get OP to blow up his house for the reduced price real estate.

Don’t fuck this up for me.

But seriously, I’ve never encountered one AHJ that requires encasement of gas lines. Electric? Yes. Gas? No. NEC specifies burial depths and when it’s acceptable to place under a slab and also allows for a depth reduction if underneath a slab. No NEC code says it MUST be under a slab, as long as the depth is maintained.