Not so much supersede as parallel requirements....ADA "always" applies and the IEBC when a permit is pulled...They should have increased accessibility at least 20% when they remodeled and the lav should have failed inspection....
Correct, and that's where Janis' blog posts have been helpful.
IEBC 705.2, and ADAS 202 for "additions and alterations" apply
when the building is altered. The alterations themselves must have accessible features, the 20% rule applies for other prioritized components, and the concept of "technically infeasible" comes into play for the owner and plan checker to evaluate. "Technically infeasible will take into account structural implications, and for a historic building, character-defining features.
When the building is
not undergoing addition or alteration, ADAS still applies, but a different concept comes into play: "readily achievable" comes into play. "Readily achievable" includes a stated listed of low-hanging fruit, such as adding grab bars.
In addition, in case of a civil lawsuit "readily achievable" is a subjective statement and is based on the available finances of the responsible parties. In the example of a small office building owned by a starving not-for-profit, "readily achievable" may mean very little work can be afforded, perhaps some signage. But if that same not-for-profit receives a billion-dollar donation windfall the next year, there may be a lot more items that the DOJ would consider "readily achievable" on that same existing building.
That's why the inspector's first step to nitpick everything that is not in technical compliance. After that, you can negotiate the subjective, grey areas of "readily achievable".
If all that sounds overly complex to you, well, you are not alone. I'm also concerned that the subjectivity in interpreting the regulations has incentivized a system of gnostic experts who get paid handsomely to navigate the complexity. If it were simpler, their services would not be in such demand. However, rent-seeking and regulatory capture are probably topics best discussed on a different thread.