Check historic, conservation, and demolition-delay overlays

The overlays that matter for an addition

Portland Maps shows every overlay on your parcel under the Zoning tab. For a second-story addition, four are decisive:

• Historic District (HD) or Historic Landmark. Means the property is in a designated historic district (Alphabet, Lair Hill, Skidmore/Old Town, Yamhill, etc.) or is individually listed. Triggers Historic Resource Review under Title 33.846. Most additions in HD areas are Type II (administrative review with public notice and 14-day appeal); larger or more visible work may go to Type III (Historic Landmarks Commission hearing).
• Conservation District (CD). Lighter-touch version of historic — Mississippi, Russell, Piedmont, Lewis & Clark, and a handful more. Conservation review is also Type II for most additions, with somewhat more flexibility on materials and detailing.
• Environmental zones (Title 33.430). Environmental Conservation (c) and Environmental Protection (p) overlays apply on lots with streams, wetlands, or steep slopes. Additions inside an "e-zone" usually need an Environmental Review in addition to the building permit.
• Demolition delay. Title 24.55 imposes a notification requirement on residential demolitions. A pure second-story addition isn't a demolition, but if your project removes more than ~50% of the existing exterior walls or the entire roof structure, PP&D may classify it as a partial demolition for the purpose of Title 24.55 — adding a 35-day public notification window on top of the permit.

How to read your Portland Maps result

1. Open portlandmaps.com and search your address.
2. Open the Zoning tab.
3. Scroll the overlay list. Anything labeled Historic District, Conservation District, Historic Landmark, Environmental Conservation/Protection, or that references Title 24.55 is decisive.

What each result means for the project

• No overlays. You're on the standard residential addition track. No additional reviews. Good news; move on.
• Conservation District only. Plan for a Type II Historic Resource Review concurrent with the building permit — adds 8–14 weeks to the permit phase and constrains exterior materials (siding, windows, trim profiles). Designer needs CD experience.
• Historic District or Historic Landmark. Type II minimum, sometimes Type III. Adds 12–24 weeks. The design will need to demonstrate compatibility with the district's character; a "modern" pop-up almost certainly won't pass.
• Environmental zone. Add 8–16 weeks for environmental review and probably an arborist + biologist on the project team.
• Demo-delay applies. Add the 35-day notification window before any demo starts. Plan around it; don't fight it.

When to escalate to a pre-application conference

If you have any overlay touching your parcel and the addition is non-trivial, request a PP&D Pre-Application Conference ($1,200–$1,800 typical) before schematic design. Two PP&D reviewers and a planner walk through your concept, name the review tracks that apply, and identify the design constraints in writing. Worth every dollar in an HD or CD lot.