Local codes limited the Detached Accessory Dwelling Unit (DADU) in size, but subterranean space wasn't included, even though in this case—the unit is nestled into a sloping hillside—it doesn't feel like a basement.  Photo 3 of 6 in Budget Breakdown: A Seattle Couple Expand Into a Backyard Addition For $413K

Budget Breakdown: A Seattle Couple Expand Into a Backyard Addition For $413K

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Local codes limited the Detached Accessory Dwelling Unit (DADU) in size, but subterranean space wasn't included, even though in this case—the unit is nestled into a sloping hillside—it doesn't feel like a basement.