Here at Istockhouseplans we have been pleased to be consulted for several local Accessory Dwelling Unit (AKA ADU, granny flat, lane housing) projects. Most, but not all, of these projects involve the homeowner creating an ADU space to move into so that they can rent out their house. We would expect the other way around. We've designed a 12x24 garage conversion, are working on turning a bonus room into an ADU, and are drafting up plans for an addition and ADU. Most of our work is in the Great Northwest but the ADU projects are very specific to Portland. Portland has very graciously extended two huge benefits to ADU builders. The first is square footage requirements. Used to be that you could build an ADU to 30% of the house square footage, max 800sf. Now that has increased to 75% of the house, still 800sf. This means smaller 1000sf homes don't have to try to work living space into 300sf, they can shoot for 750sf. But really, 300sf is still doable.
The second benefit is the temporary elimination of systems development charges on a permit when building an ADU. In some cases this fee can be thousands and thousands of dollars. But in order to try to encourage higher density (and avoid sprawl) the fees are reduced or in most cases eliminated for a while. The one caveat with all ADU spaces is that the property owner must live either in the house or the ADU. Not allowed to rent out both. Not that that stops folks from doing so.
If you've been considering an ADU on your property, let us know if we can help. We already have a host of plans that could be used for an ADU as well as garage options with living space. Of course every property is different. If nothing works for you let us know. We are eager to design small and beautiful.