Therefore a two or three bedroom property cannot rent more than one bedroom at a time.The rental portion of the residence must be designated as an accessory use space.Must include the registration number in all advertisements.

The link to the requirement is here http://www.seattle.gov/sdci/permits/common-projects/accessory-dwelling-unitsDo you know any other cities in the greater Seattle area with similar regulations.

Within the city limits (I think both suburban and urban tiers) you can now have, by right, up to 3 units (2 in the form of a duplex and 1 in the form of a detached accessory dwelling unit).Of course, the problem is that construction costs are so high, ADUs are difficult, but if you have a garage that could be converted easily, that could be a good way to go!

What I beleive you want to research regarding the detached carriage house is a dwelling called an "Accessory Dwelling Unit" (ADU). 

I'm excited to see what will happen with the new ADU legislation (accessory dwelling unit) that they passed and how infill developers will be taking advantage of said legislation.

While my immediate priority is a day job in the real estate field, my wife and I are nearly done with the architecture plans to build a detached Accessory Dwelling Unit (ADU) on our property and add an immediate cash flow generating rental unit.

One thing to look into it to see if you can put an accessory structure.

Most the info came from the county accessory website that is already free.

When it comes to tax strategy for a property with an accessory dwelling unit (ADU), there are a few considerations to keep in mind.

We are considering pulling equity (HELOC) and adding an accessory dwelling unit in the back yard.