Sometimes the occupants of the home are going to have a progressive condition - arthritis, multiple sclerosis, muscular dystrophy, a stroke, a heart condition, diabetes, or other impairment or ailment. Sometimes it's going to be a mobility issue due to inflammation or deteriorating joints (hips, knees, shoulders, or ankles, for instance). These issues manifest themselves in how well someone gets around their space, climbs stairs, sits, squats, bends, stands, or reaches for and retrieves objects from closets, dressers, or cabinets. Sensory issues, especially vision, also impact how well people use and relate to the living space.
Generally, an occupational therapist or other healthcare professional is going to be consulted before designing and creating any home improvements. They have the training and background that enables them to determine how people relate to their space and specifically what might be required to make their homes safer, more accessible, comfortable, and convenient for them to use.
Thus, there are two important considerations for creating aging in place environments for our clients. The first is the home itself - regardless of who is occupying it. The second is the specific needs, requirements, and characteristics of those residing in the living space as well as those who might come into it from time-to-time.
Both approaches are important. The physical characteristics of the home - doorway and hallway widths, door swings, height of counters and wall cabinets, access to the bathroom and shower facilities, and so much more - affect and impact how well the occupants of that space are going to enjoy living in the home and find performing normal everyday activities to be safe and pleasant. Then, the physical limitations or issues that the people living in the home are experiencing and living with are going to have a bearing on how they relate to their home and find it functional for them.
For the total aging in place solution, we must consider and address the requirements of the individuals living in the dwelling space (and those coming into that space occasionally from the outside). Starting with the home is fine, but looking at the individuals is important also.