Funny, I was sure I had read from the city's web site somewhere that only one accessory building is allowed, but reading the zoning ordinances they allow 2. Problem kind of solved..
Internet searches had turned up this document:
http://www.docstoc.com/docs/8389041/City-Of-Royal-Oak
It is dated 2001 and states city code 770-36(A) 1 says "Only one main building (house) and one accessory building (garage or shed) are allowed per residential lot."
But searching on the city's web site turns up:
http://ecode360.com/?custid=ro2029
And under 770-22(A) 1 it states: "No accessory building shall be built upon a lot or parcel unless and until a principal building is erected, and shall not exceed two accessory structures per lot."
under the current rules 770-36 is for 2 family units, so I guess what I had found earlier must be outdated. 770-34 is for single family lots and points back to 770-22.