Hi Kate!
Good question. I've been working on competencies for library staff, but I must admit I haven't included those for custodial staff.
This job description for a
Facility Maintenance Supervisor has a solid list from which to select the things that apply to your library situation.
Also, this LE@D course on
Keeping Your Library Looking Good will help you hire custodial staff who can deal with those library-specific problems, like graffiti on the restroom walls or tar on the carpets.
I'm sure others have the same question and may have some good answers. Please share!