Add structural engineer to that list.
You guys keep talking about custom homes. Don't you think the builder has a responsibility for ALL homes he builds, whether it is custom or spec? All homes regardless should meet at least MINIMUM code requirements. And if it is a good builder, it will meet better than minimum.
I learned through my experience that building codes are quite complex and disagree that the homeowner should have to know them . Sadly, unless you KNOW code, then anything can be pulled on you. That is why there are Licensed Builders, so their subs and employees build to meet code.
I am NOT in the building business, nor did I ever want to know the amount that I do now.
I would like to think there are people out there who have integrity and will oversee projects without the homeowner questioning them on everything they do. After my experience, I have fears about any house that was built here in the last many years.
I am not saying there are NOT builders with integrity that people can put their full trust into, but I have found and seen that there are plenty that you can't. Not just my builder, I have seen some amazing things other builders do and can't believe what some try to get away with.
One of the first questions I ask my new builder is "do you have any problems with me being on site every day?" If they balk at that, I run.