Roof deck and ADA compliant?

Our mid rise co-op has a fair amount of roof space with a really nice view. We’d like to add a roof deck, however our Engineer has informed us that we can not because it would have to be ADA compliant. There is no elevator to the roof (one flight of stairs from the PH floor to the roof). We are told it would be cost prohibitive ($1M) to add access that would be ADA compliant. Are there any alternative approaches that anyone is aware of? It’s such a waste of great space that all shareholders would benefit from. I’ve been on other roofs that don’t have elevator access. Is there a way to get this done without elevator access? Thanks for any advice!