What Makes a Good ADU Floor Plan?

Two 600 SF units. Same budget, same lot. One feels like a boutique apartment; the other feels like a hallway with rooms attached. The difference is six principles — learn them and you'll evaluate any plan like a pro.

1. Zone public and private. Living, kitchen, and dining are public; bedroom and bath are private. Good plans cluster each zone and put the public zone at the entry. When guests must cross the bedroom's doorway to reach the sofa, the plan failed this test.

2. Protect the entry sightline. What you see standing in the doorway is the home's first impression. Best case: living space and a window beyond. Worst cases: the toilet (surprisingly common in bad plans) or the entire kitchen's dirty dishes. Move a door two feet on paper and the whole unit feels different.

3. Hallways are theft. Every square foot of corridor is space you paid ~$375 for that stores nothing, seats no one, sleeps no one. Great small plans use rooms to reach rooms, or one short gallery doing double duty. Target: under 5% of floor area in circulation.

4. Group the wet walls. Kitchen and bath sharing a plumbing wall (or stacking tightly) saves thousands in pipes and venting — you learned this in Module 4; in design review it's the first thing to check on any plan.

5. Light from two sides. Rooms with windows on two walls feel calm and bigger than they are; rooms lit from one side feel like offices. Corners are free — use them. And one generous window beats three mean ones.

6. Storage is a room's silent roommate. A plan without a coat spot, a linen cabinet, and real closets forces the furniture to do storage's job — and small rooms full of storage furniture stop being rooms. Build storage into the walls (lesson 8.7 goes deep).

How to use this lesson: when reviewing any proposed plan, walk it mentally: enter, hang a coat, cook dinner, host two friends, go to bed, get up at 2 AM. Every stumble in the mental walk is a real stumble you'll live with — or your tenant will price into the rent.