I love and appreciate the debate… the way I’ve always understood it is that codes are written with safety in mind for the most part. Exceptions being things like earthquake resistance/structural, energy efficiency, etc. So, (most) codes=safety. So, if codes are written for safety how can you grandfather one but not the other. That’s why I keep bringing up the list of every code change that’s happened for the last 100+ years. I feel like a lot in our industry are leading people (their clients which is the most concerning) to believe that is what they are doing at their HI which is a gross exaggeration of anyone’s ability and what is really taking place at an inspection.
Of course, I know a bunch of codes and what years things were enacted and use a lot of that when I inspect but stop well short of ever citing anything specific or really caring too much about a particular code cycle for a minor/moderate change… like OP’s firewall (sorry OP, not trying to beat you up). I guess my point is that codes are for jurisdiction inspectors not HIs. I’ve trained/worked with probably 50+ inspectors over the years and the guys that struggled the most needed black and white (a code book). There’s A LOT of gray in home inspections. Again, great debate!