Case Study: The Two-Story ADU

1. The property. A narrow 5,400 SF lot in a hillside-adjacent LA neighborhood; the house and driveway consumed most of it, leaving a 24-by-30-foot buildable pocket at the rear — with an SCE service line crossing one corner.

2. The goal. A full 2-bedroom unit for the owner's mother and, eventually, market rental — needing real square footage on a lot that "was full."

3. The constraints. The pocket capped a single-story unit near 550 SF after setbacks — too small for the program. The city, helpfully, allowed detached ADUs to 25 feet (13.7's route #1). The power line imposed a clearance cone over the northeast corner (2.4), and the neighbors' rear windows looked directly at the site (8.5, hard mode).

4. Options considered. (a) A 550 SF single-story 1BR — fits, fails the program. (b) An attached ADU — the house's layout made the connection surgical and the owner's mother wanted separation. (c) Two stories: ~430 SF footprint, ~820 SF total. The choice was really made by the program: only (c) delivered two bedrooms. The honest 13.7 premium (~15% per SF here) was accepted with eyes open.

5. The final design. Sleeping down, living up — inverted from convention because the second floor cleared the fences into tree canopy (8.6): bedrooms and bath on the ground floor (mom's aging-in-place future pulled one bedroom + full bath downstairs — 8.9's arc thinking), kitchen/living upstairs with the view. The building massed away from the power-line corner, roof held under the clearance cone — the structure literally shaped by the utility diagram. Upstairs windows faced the canopy; the neighbor-facing wall got clerestories only (8.5's toolkit, fully deployed).

6. City issues. One planning comment on height measurement method (2.3's fine print, encountered in the wild) — resolved by resubmitting elevations dimensioned to the city's specific standard.

7. Permitting. Two correction rounds — the structural package (stacked loads, a steel moment frame at the big upstairs window wall — 9.3 and 13.7's cost warnings, both realized) drew most items. 16 weeks.

8. Construction. 9 months. SCE's clearance was verified twice: at design and again with a field visit before roof framing (12.4 at height is unforgiving of assumptions). Scaffolding, the crane day for roof trusses, and the moment frame were the visible costs of verticality.

9. The final result. An 815 SF 2BR whose upstairs living room — floating in tree canopy — is the best room on the entire property, main house included. Mom took the downstairs suite; the stair (run along an exterior wall, storage beneath — 13.7's moves) reads as architecture, not circulation.

10. Cost range. $355,000–$380,000 all-in — the ~15% vertical premium visible and, per the owner, worth it.

11. Timeline. About 16 months end to end.

12. Lessons learned. Two-story ADUs are program-driven decisions, not preference-driven ones — this lot simply had no horizontal answer. The power line was designed around from day one and never became a problem; discovered at framing it would have been a catastrophe. And inverting the plan (living up) turned the constraint lot into the best view on the street.