Choose: pre-approved plan vs. custom designer

The two paths

Pre-approved plan sets. A handful of Portland-active firms offer plan sets that have already cleared structural and energy-code review for a typical Portland lot. You buy the set, customize finishes and minor layout, and submit. Plan review is faster because the structural and energy packages are pre-vetted.

• Cost: $3,000-$8,000 for the plan set + $4,000-$8,000 in customization
• Time to permit-ready: 4-8 weeks
• Trade-off: limited footprint and configuration; you fit the lot to the plan, not the other way around

Custom design. A designer or architect draws from scratch for your specific lot.

• Cost: $12,000-$28,000 in design fees (more if architect stamping is required)
• Time to permit-ready: 12-20 weeks
• Trade-off: longer and more expensive, but you can handle unusual lots, trees, or specific owner preferences

When Portland requires a licensed architect

Most single-story DADUs ≤800 sq ft in standard zones can be designed by a non-architect drafter or designer. An Oregon-licensed architect is required when the project crosses the threshold in ORS 671.030 — roughly: more than two stories, non-standard structural systems, or certain occupancies. A structural engineer's stamp on the framing plan is almost always required either way.

How to pick

• Tight standard rectangular lot, no trees in the way, conventional layout? Pre-approved.
• Trees, slope, odd shape, specific owner needs? Custom.
• Time-constrained (e.g., aging-in-place)? Pre-approved.