There is already an International Building Code and other such construction codes that are adopted into many state statutes with appropriate amendments suited for that state. Depending of state statute local governments usually reference the adopted codes in their ordinances making or adding changes as allowed under state law.
So you already pretty much have voluntary adoption of a uniform code as needed. So requiring a federal building code would be overkill.
The Fed wants to be in exclusive charge of all future changes to the codes along with enforcement.