Olympia, WA · zoning record
The dimensional standards that govern what you can build in the RM-18 district, straight from Olympia's ordinance, with every figure quoting its source. Check a specific address to see how these rules apply to a real lot.
Free · Every figure cited · Read from the current code (2026-09-21)
In Olympia's RM-18 district the maximum height is 35 ft (Olympia code 18.04.080(I), read 2026-09-21).
In Olympia's RM-18 district a lot may hold up to 18 dwelling units (Olympia code 18.04.080(A), read 2026-09-21).
In Olympia's RM-18 district the minimum lot size is 3,000 sq ft (Olympia code 18.04.080(C) 18.04.080(D) 18.04.080(E) 18.04.080(F) Chapter 18.64 (townhouses) 18.04.060(P) (mobile home parks), read 2026-09-21).
In Olympia's RM-18 district the minimum front setback is 10 ft (Olympia code 18.04.080(H) 18.04.080(I) Minimum of 20 feet from front property line adjacent to a street to vehicle access to garage or carport, read 2026-09-21).
In Olympia's RM-18 district the minimum interior side setback is 5 ft (Olympia code 18.04.080(H), read 2026-09-21).
In Olympia's RM-18 district the minimum rear setback is 10 ft (Olympia code 18.04.080(D) 18.04.080(F) 18.04.080(H) 18.04.080(I), read 2026-09-21).
In Olympia's RM-18 district impervious cover may not exceed 65% (Olympia code 18.04.080(K) 18.64.080, read 2026-09-21).
In Olympia's RM-18 district an accessory structure may be up to 24 ft tall (Olympia code 18.04.080(I), read 2026-09-21).
In Olympia's RM-18 district an accessory dwelling unit may be up to 24 ft tall (Olympia code 18.04.080(I), read 2026-09-21).
These are the letter-of-the-law limits for the base RM-18 district. Overlays (historic, neighborhood plan, and similar) can tighten them; a specific address check resolves the overlays that actually apply.
How tall the building may be.
“MAXIMUM BUILDING HEIGHT | 40’ | 40’, except: 24’ for detached accessory structures and dwelling units | 40’ except: 24’ for detached accessory structures and dwelling units | 40’ except: 24’ for detached accessory structures and dwelling…”18.04.080(I) · Olympia code · read 2026-09-21
How many homes the lot may hold.
18.04.080(A) · Olympia code · read 2026-09-21Row as published
“MAXIMUM HOUSING DENSITY (in units per acre) | 1/5 | 4 | 4 | 4 | 8 | 12 | 13 | 18 | 18 | 24 | --- | --- | 12 | --- | 18.04.080(A)”
Smallest conforming lot.
18.04.080(C) 18.04.080(D) 18.04.080(E) 18.04.080(F) Chapter 18.64 (townhouses) 18.04.060(P) (mobile home parks) · Olympia code · read 2026-09-21Row as published
“MINIMUM LOT SIZE | 4 acres for residential use; 5 acres for non-residential use | 5,000 SF; except: Townhouse = 2,000 SF | One acre; reduced to 12,000 SF if associated with a drainage dispersal tract of at least 65% in the same subdivision plat. | 4,000 SF; except: Townhouse = 2,000 SF | 4,000 SF; except: Cottages = 2,500 SF; Townhouse = 2,000 SF | 3,500 SF; except: Cottages = 2,000 SF; Townhouse = 1,600 use | 3,000 SF; except: Cottage = 1,600 SF; Townhouse = 1,600 SF | 3,000 SF; except: Cottage = 1,600 SF; Townhouse = 1,600 SF | 3,000 SF; except: Cottage = 1,600 SF; Townhouse = 1,600 SF | Townhouse = 1,600 SF Mobile Home Parks = 2,500 SF | Townhouse = 1,600 SF Mobile Home Parks = 2,500 SF | Townhouse = 1,600 SF | 3,500 SF; except: Cottage =- 2,000 SF; Townhouse = 1,600 SF | Townhouse = 1,600 SF minimum, 2,000 SF average; Mobile Home Park = 2,500 SF | 18.04.080(C) 18.04.080(D) 18.04.080(E) 18.04.080(F) Chapter 18.64 (townhouses) 18.04.060(P) (mobile home parks)”
Required space from the front line.
“MINIMUM FRONT YARD SETBACKS | 20’ except: 5’ for agricultural buildings with farm animals | 10’ | 10’ | 10’, 5’ for agricultural buildings with farm animals | 10’, 5’ for agricultural buildings with farm animals | 10’, 5’ for agricultura…”18.04.080(H) 18.04.080(I) Minimum of 20 feet from front property line adjacent to a street to vehicle access to garage or carport · Olympia code · read 2026-09-21
Required space from a side line.
“MINIMUM SIDE YARD SETBACKS | 5’ except: 10’ along flanking streets; provided garages are set back 20’ | 5’ except: 10’ along flanking street; except garages must meet Minimum Front Yard Setbacks | 5’ | 5’ except: 10’ along flanking stree…”18.04.080(H) · Olympia code · read 2026-09-21
Required space from the rear line.
“MINIMUM REAR YARD SETBACKS | 10’ | 10’ | 10’ | 10’ | 10’ | 10’ | 10’ | 10’ | 10’ except: 15’ for large multifamily | 10’ except: 20’ next to an R 4-8 or R 6-12 district | 5’ except: 20’ for structures 35’ or higher | 5’ | 5’ | 5’ except:…”18.04.080(D) 18.04.080(F) 18.04.080(H) 18.04.080(I) · Olympia code · read 2026-09-21
Share of the lot that may be hard surface.
18.04.080(K) 18.64.080 · Olympia code · read 2026-09-21Row as published
“MAXIMUM IMPERVIOUS SURFACE COVERAGE | 45% or 10,000sf (whichever is greater) = lots less than 4 acres; 6%=4.1 acre or more | 35% | 6% | 2,500 SF or 6% coverage whichever is greater. | 55% | 55% | 65% | 65% | 65% | 75% | 85% | 85% | 65% 25% = 3.01 + acres 70% = townhouses | 85% | 18.04.080(K) 18.64.080”
How tall an accessory structure may be.
“MAXIMUM BUILDING HEIGHT | 40’ | 40’, except: 24’ for detached accessory structures and dwelling units | 40’ except: 24’ for detached accessory structures and dwelling units | 40’ except: 24’ for detached accessory structures and dwelling…”18.04.080(I) · Olympia code · read 2026-09-21
How tall an accessory dwelling unit may be.
“MAXIMUM BUILDING HEIGHT | 40’ | 40’, except: 24’ for detached accessory structures and dwelling units | 40’ except: 24’ for detached accessory structures and dwelling units | 40’ except: 24’ for detached accessory structures and dwelling…”18.04.080(I) · Olympia code · read 2026-09-21
Every figure above is quoted verbatim from the current ordinance. We never substitute a typical-for-zone default: a field absent from the record shows nothing, not a guess.
See how these standards resolve on a specific parcel, with the overlays that actually apply, in about 20 seconds.
Free to score · No card, no signup · All 50 states
Buildability