It's not easy getting around most homes in a wheelchair. If you can't enlarge doorways or remove doors, use a narrow wheelchair, called a transport wheelchair, to get through narrow doorways.
Ramp Design Factors
These ramp videos are not dementia-specific, but offer excellent suggestions for Do's and Don'ts when building a ramp. You'll view people with mobility impairments using ramps in a variety of ways, (e.g., with crutches, walkers, and wheelchairs) and see how the design of the ramp affects safety and ease of use.