We have written a few blogs recently about Accessory Dwelling Units (ADUs) and therefore wanted to further address them. But before we start, do you know the difference between an ADU, Casita, Guest House and Mother-in-Law Suite? Depending on your market area, they can mean different things and sometimes are inner changeable. Here in Arizona, Casita is used in replace of guest house, where there is a separate living area from the main Gross Living Area. Typically, here in Arizona, mother-in-law suites are actually within the GLA and just a separate end of the house that includes a bedroom, bathroom and kitchenette (no stove top or oven) with an electric hot plate or sink and mini-fridge. ADUs are separate dwellings with fully functioning kitchens (stove top and oven). As mentioned before, zoning is a key to determine if the property has a legally functioning ADU. If zoning does not allow for an ADU, then an appraiser should give value to the amenity as a casita or guest house. If zoning allows for an ADU, then the key difference between a casita and an ADU is a legal full kitchen. Having a full kitchen classifies the unit as a separate dwelling. There is a bathroom, bedroom, living area, full kitchen and likely separately metered. Note: Casitas or Guest Houses are not counted in the GLA. If there is a mother in law suite, it would have interior access to the main dwelling and thus would be included in the GLA. ADUs, due to being considered a separate dwelling are also not included in the GLA. If they are not considered in the GLA, they should be given contributory value on the grid as a line item. However, not all markets are the same and some amenities are not given value due to various reasons. The Many Styles of an Accessory Dwelling Unit Image from: AARP website The next question might be: When is it considered an ADU verses a multi family property? If they are both separate dwellings couldn't ADUs be considered multi family type properties? The answer to this question would lead into a Highest and Best Use Analysis. Keep checking back as Highest and Best Use will be discussed in a future blog. Until then, see if you can spot these different types of ADUs when driving through your neighborhoods.