If it was within code how was the builder supposed to know what problems would occur years down the road? The issue isn’t workmanship or competency on the builder’s part, but problematic materials.
If he skimped on the concrete mix and watered it down by mistake or cutting corners, then yes he’d be liable. If the concrete he bought was bad from the manufacturer when he had no reason to think it would be, why would he be liable?
Another company, Lennar, has replaced their chinese drywall in another location in Florida. So it appears the builders are stepping up to correct the defects. Now, as to liability, maybe they aren't liable - but the homeowner contracted with them to build a liveable home and the builder ended up using a product that was not safe.
Why are so many products from China *TOXIC*??? Seems everything electronic, rubber or plastic, especially, is so STINKY, it makes you sick to be in the same room with it. (HATE to walk thru Sears or Costco Automative Department; the STENCH from the TIRES & other plastics makes you want to give up the ghost! Feel sorry for the employees who have to work in these toxic dumps; don’t they get brain damage or something from breathing those fumes??)
We have a Surge Protector from China that smells very toxic. Also, we recently bought a flat-screen Vizio TV from Costco that STUNK TO HIGH HEAVEN for many weeks; finally took it back and instead bought a Sony from BestBuy. No odors! :-)