Millennials have seen the traditional starter homes fade from the market. Baby boomers are retiring and finding homes friendly to the elderly in short supply as well. Renovating homes for wheelchair access and other accommodations is expensive. I've had my own brush with being handicapped, too.
What can be done about this situation? Not much. New construction is expensive, and government fiscal policy incentivizes bigger and bigger "family homes" with easy credit. I can, however, start drawing blueprints. I am a draftsman by training, after all.
I am hitting a few roadblocks as I sketch my preliminary designs, though. The starter homes my parents and grandparents remember do not meet modern building codes. They are also rarely accessible to wheelchairs and other mobility aids. Some building codes seem arbitrary, but accessibility minimums are set by physical reality, so let's go over a few basics without migraine-inducing legalese. These are also minimums for accessibility, so more space should be allowed where possible. Wheelchair access is my base metric because that's what dictates the most for a floor plan, but electric receptacle height, light switch location, countertop height, and more also affect accessibility for myriad situations.
I'll be relying on imperial units because that's what we use in the USA. For those unfamiliar with our quaint system and its notation, a single quote tick denotes feet, and a double tick denotes inches, so to write that one foot equals twelve inches, I would write the following: 1'=12". 1"=25.4mm exactly, but as a rule of thumb, 4"=10cm, 12"=30cm, and so on for quick-and-dirty conversions.
Enough beating around the bush. Time to list some basic design requirements.
Allow at least a 60" unobstructed turning circle in a kitchen or restroom. If a full circle cannot be provided, a T- or L-shaped turning space can sometimes be allowed. Some obstructions with allowance for knee and toe space, i.e. restroom sinks, are allowed. Doors can open into this space as well.
36" minimum for a straight corridor, or 42" minimum to allow for turning. This also applies to the T- and L-shaped turning spaces above.
32" minimum clear width when the door is opened to 90°. My recommendation is just round up to 36" since it is a common size for pre-hung door assemblies, and a little extra space is always welcome.
Varies by door configuration. Here's an official table of data and a diagram.
We generally design interiors to be flat, but access from outside always involves some degree of elevation change. When I worked for an architectural firm, it always seemed like site grade and wheelchair ramps were the most difficult to ensure we kept in spec, whether remodeling an existing structure or building new on uneven terrain. 
Just these basic wheelchair maneuvering requirements should hint at how much work it takes to design commercial and residential spaces which meet modern standards. Incorporating them into a space from the start of the design process is far easier than remodeling an existing structure, though, and this isn't just beneficial for the handicapped. Have you ever moved furniture down a narrow hallway, pushed a baby stroller through a public space, or moved an appliance on a dolly?
With that in mind, here are the general features I want to include from the start for a starter/retirement home, at least for the main floor plan.
The main floor must include, at a minimum, the kitchen, bath, laundry, one bedroom, and a living room or parlor with full wheelchair access. This requires space, so the floor plan will necessarily be expanded from that of the postwar housing which inspired the plans I am drawing.
Private bedroom and bathroom spaces must be separated from the more public living space by a short hall to break line of sight and provide a barrier to sound, but this hall should be a minimum of 42" wide, and allow ample turning space at each doorway.
Kitchen and bath must include a clear turning circle, and ideally be designed from the start with accessible cabinets and sinks. More on that after I sort the floor plan and start drawing interior details, hopefully in an upcoming post.
One more thing: as someone who has always lived in states adjacent to Canada, snow is an annual concern. Therefore, not only should the front door include a porch and wheelchair ramp, it should be covered by a roof to keep the snow off. Handicapped or not, shoveling snow sucks, and too many mass-built tract homes dump snow right onto the front steps. This is dumb and I will not tolerate it in my own designs.
Attached garages at the front of a house are ugly. They are also typically at grade below the floor level of the home, and offer little room for a suitable ramp, and can introduce exhaust fumes and other chemicals into the home. In my not-so-humble opinion, most homes are better served by a carport near the house and/or a detached garage.
What do you like about older, smaller homes you may have had in the past? What little annoyances about your home should be designed away from the start? Have you had any experience with accessibility issues? What rules are used in the metric world for I'm still at the drawing stage, and would welcome suggestions. Hopefully I'll also find a good way to share PDF files for plans as I develop them.
Wheelchair image credit: Vicki Hamilton on Pixabay
All other images: U.S. Access Board ADA Accessibility Standards, public domain
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