I can enter dimensions in fractions but then can only see dimensions ofr objects in decimals. I live in the US and I'm using blender to create build plans. For the plans to be useful to people in the trades dimensions need to be shown in fractions.
I'm afraid it's not possible at the moment to have something like 5 3/8". Request this feature or try to find a Python script. And it's possible to import, with an app, .obj files to AutoCad and do the measuring there with fractions supported. Blender's primary goal is not architecture/housing.