There is a very good chance the house is operating in excess of the maximum occupancy permitted {here it is 4 unrelated adults} and outside the zoning for the neighbourhood. 

Your young age isn't really much of an issue - as soon as you turn 18 you're a legal adult and banks will view you just as anyone else.As far as getting a traditional mortgage loan though, you'll still need the same 2 factors everyone else does: credit and income.  

Buyers are willing to pay $$$ for additional flexible spaces that can be used as office, gym, guest home for elderly parents or adult kids, or simply as rental to help pay off the mortgage.

I am interested in opening up a group home to serve adults with special needs, as I have two siblings who will eventually need this type of care.

Not to mention the impact on parking, trash, etc. that just happens if you want to cram 5+ adults in 5 bedrooms.  

Sorry mate, adult ADHD kicked in.

I have worked in construction and wholesale plumbing sales my entire adult life (I am 30). 

Many people use tenantreports.com  the cost is around 28 and we charge 30 for the application for each adult over 18.A lot of tenant headache can be minimized also by the property itself.

A parent df a developmentally disabled adult accomplished just that and is willing to guide us through the process.

With that said, one of my units, 2 bed 2 ba, has 2 adults and 4 children, rent for $650.