I want to build an accessory dwelling unit on my property in Western Massachusetts.

Days on market a little longer and price not appreciating as quickly in good neighborhoods and have def dropped a bit in some other less coveted areas.In the past when the markets slowed SF Bay Area on average dropped about 10%.

OR . . . .Should I build a legal ADU (accessory dwelling unit) over my detached two-car garage in my backyard? 

It adds more value in the long run when you go to sell it when you can say "legal accessory apartment."

If you’re in a pinch and need to do some work yourself, I’d consider doing the demolition, landscaping, and if the market supports it, assembling RTA cabinets.If you have the know-how, installing plumbing fixtures, electrical fixtures and bathroom accessories is another thing you could do to save a bit of money. 

Good morning investors, contractors, homeowners, banks, and code enforcement persons.  I have a question about what can and cannot be done as far as adu's are concerned?  I know there are limitations and certain zonin...

A DADU, or detached accessory dwelling unit, is a VERY rare one!

Durham allows detached or attached accessory dwelling units citywide.

These areas, designated by a new “z” Constrained Sites overlay zone, will retain existing regulations for corner duplexes or one accessory dwelling unit with a house.Lots that do not meet minimum lot sizes for three or four units (R2.5 = 3,200 sq ft; R5 = 4,500 sq ft; R7 = 5,000 sq ft)Infrastructure constraints, including lack of paved streets, sewer or water service.Increase the allowed size (FAR) for duplexes and triplexes (no increase for a fourplex).

The lot has a small accessory dwelling unit, and we plan to build a larger main home.