Small ADU — 480 sq ft

#PLN-98F8FFA1Search this code in Explore or Google with “PlanGrounds”.

This is an example plan — for reference only, not from a real listing.

by Chen Design CoSeattle, WA, USAMarch 2026

Size

480 sq ft

Beds

Baths

Floors

Planning estimate · design services

Guidance based on this plan's type, size, and region signal — not a binding proposal. How planning estimates work.

$7,049.00 – $23,744.00(7–14% of project budget)

Confidence: medium — varies with site, code, and scope

·Based on plan customization scope
·ADU
·~480 sq ft
·Location: WA, US
·Schematic design

Often increases scope / cost

• Smaller projects often see a higher effective percentage.

Start your project → refine this estimate with your site and goals

Gallery

PLN-98F8FFA1

Preview — purchase for usable files

PLN-98F8FFA1

Preview — purchase for usable files

Floor Plan

Detailed floor plans available upon inquiry

Description

About this plan

The Small ADU packs remarkable livability into 480 square feet. Designed for backyard lots in Portland, Seattle, and similar Pacific Northwest cities, this plan meets common ADU code requirements while feeling spacious and considered. The open living/kitchen area uses 10-foot ceilings and a wall of glass to dissolve boundaries between indoor and outdoor space. A covered entry porch doubles as an outdoor dining area in good weather. The kitchen features full-sized appliances and a breakfast bar. The bedroom is generously proportioned with a walk-in closet and direct access to the bathroom, which includes a walk-in shower, floating vanity, and laundry stack closet. Built with aging-in-place principles: zero-step entry, 36" doorways, blocking for future grab bars, and lever hardware throughout. This plan has been successfully permitted and built in Portland, OR and Seattle, WA.

minimalist

adu