Take a number like two-fourths. It represents one-half but is expressed in a somewhat larger form. When we divide both the numerator (top number in the fraction) and the denominator (the bottom half of the fraction) by two (the lowest common denominator), we get one-half. This fraction cannot be reduced any further.
This describes how universal applies to what we evaluate, recommend, select, and implement as changes and renovations for people to have in their homes - regardless of their age or ability, or even the age of their home or apartment - that will enable them to continue to live in those homes safely and comfortably.
People may desire to remain in those homes long-term, or they may have a shorter term in mind. Regardless, our outlook and effort can be essentially the same. This is where the idea of lowest or smallest common denominator for universal design comes into play.
Obviously for aging-in-place solutions where a particular circumstance needs to be addressed, a more general type of solution may not be appropriate. However, the idea of universal design means that most anyone, of any physical size, age, or ability, can use and benefit from what it installed or created.
So, we begin with one of the core principles of universal design - simplicity. We add to that two other key concepts - ease of use and low physical effort. This is how the lowest common denominator idea is applied.
We take a solution that is simple in design, easy for people to use, attractive or unnoticeable in a space as being anything special or different, and effective for the residents of that home, and we recommend it.
We want to select a solution that appeals to and is appropriate for nearly every person that lives in that home or apartment or ever visits it (whether for a few minutes or several days). Even when someone has a more specific need, universal design will generally allow them some use of a universal design feature.
It is looking at and evaluating the needs of the people in the home - whether that same recommendation would be made for a similar home or not - and determining what is that feature, control, device, piece of furniture, or other item that can be used by everyone in the home, starting with the person who might have the most difficulty or challenges in doing so.
When this is achieved, all in the home will benefit.
When we design space or allow for movement of individuals with wheelchairs, that same approach accommodates persons without wheelchairs or other forms of mobility assistance just as well.
It's selecting a design, feature, or approach to appeal to the most essential need in the home and then determining that it applies to everyone else in the home as well. When there is nothing specific that needs to be addressed other that safety, comfort, convenience, or moving about within the space, making sure that both the smallest and largest individuals in the home and the oldest and youngest (except for very small children) can use and function well in what is created.