Hoo BOY! This PDF download is 390 pages long ( but free ! ) and is geared towards how to design and build multi-unit housing for seniors, people with disabilities, youth, homeless people and low income families.

So why post it here?

Well, there is excellent design advice in the section on individual dwelling units for designing and building a living unit  that you can age into (starting on Page 33).

All the information can be applied to a stand-alone home, and since everyone wants to stay in their home for as long as possible, if you design it now for “aging-in-place” you can put off moving into a retirement castle until much later in life.

https://www.bchousing.org/publications/BCH-Design-Guidelines-Construction-Standards.pdf