Tree review (Title 11) and Historic Resource Review if overlay applies

Tree review under Title 11

Portland Urban Forestry reviews any project near regulated trees. The threshold:

• Trees with a diameter at breast height (DBH) of 12 inches or more in residential zones are regulated.
• Heritage trees (designated individually or in groups) are protected at any size.
• City-owned street trees in the right-of-way are always regulated.

A second-story addition rarely removes trees, but it almost always involves construction activity in tree root zones. Urban Forestry asks for a tree preservation plan with the addition application:

• Survey identifying every regulated tree on the lot and within 25 ft of the work.
• Tree protection zones (TPZ) per Title 11, typically 1 ft of radius per inch of DBH.
• Construction-fence specs to protect TPZs.
• Arborist sign-off if construction activity enters a TPZ.

Most additions clear tree review without removing anything — preservation plan + fenced TPZs is enough. Removal of a regulated tree requires a separate tree permit, mitigation planting, and possibly an arborist's report justifying the removal.

Historic Resource Review if HD/CD applies

If your overlay check in feasibility flagged a Historic District (HD) or Conservation District (CD), Title 33.846 Historic Resource Review applies. Three review types:

• Type I (administrative, no notice). Minor work — paint, in-kind window replacement, small repairs. Most additions don't qualify for Type I.
• Type II (administrative with notice + 14-day appeal). Most additions in HD/CD lots. PP&D historic-review staff issue the decision; appeals go to the Landmarks Commission.
• Type III (Landmarks Commission hearing). Larger or more visible additions, particularly in central-city districts. Public hearing; written decision with conditions.

The review focuses on compatibility with the district's character: massing, materials, fenestration rhythm, roof shape, trim profiles. A modern pop-up on a Craftsman in Alphabet HD won't pass; a sympathetic addition that reads as period-appropriate will.

Timing

• Tree review runs 2–6 weeks; usually doesn't extend the building permit timeline.
• Historic Type II runs 8–14 weeks; can extend the building permit if comments require design changes.
• Historic Type III runs 16–24 weeks; typically the long pole on HD lots.

Fees

• Tree: $100–$1,500 depending on whether removal is involved.
• Historic Type II: ~$1,500–$5,000 (varies with project size).
• Historic Type III: $5,000–$15,000 + applicant cost for hearing materials.

What experienced HD designers do differently

• They submit a pre-application conference request to PP&D historic staff before schematic. Two-hour meeting; staff identify the design constraints in writing. Pays for itself.
• They pick exterior materials from the district's pattern book, not from their preferred vendor list.
• They attend Landmarks Commission hearings for similar projects to read which arguments land and which don't.
• They build in a Type III contingency in the schedule even if Type II is targeted — staff sometimes elevate the review path mid-process.