The fastest way to derail an ADU is to start with finishes before you’ve solved the fundamentals. Before sketches get serious, map constraints: access for crews, utility tie-ins, drainage, and how the unit will sit for sunlight and privacy. These factors often drive cost more than square footage. Sound control is easiest to build in early: insulation choices, resilient channels, solid-core doors, and smart room placement. On the build side, prioritize moisture control, insulation, ventilation, and sound separation. Those details determine whether the space feels quiet and comfortable year-round. If you want a practical place to start, use https://traveleworld.com/san-jose-adu-builders-14/>detached adu as your reference point. Keep a short list of non-negotiables so decisions stay consistent as options multiply. If you’re collecting bids, ask for a written scope with exclusions listed—this prevents misunderstandings later. If you’re collecting bids, ask for a written scope with exclusions listed—this prevents misunderstandings later. If you’re collecting bids, ask for a written scope with exclusions listed—this prevents misunderstandings later. When in doubt, simplify—fewer custom details often means faster progress and cleaner results. If you’re collecting bids, ask for a written scope with exclusions listed—this prevents misunderstandings later.