Before You Build in Bellingham, WA: Permit & Rule Checklist (2026)

Bellingham exempts retaining walls not over 4 feet (1,219 mm) in height measured from the bottom of the footing to the top of the wall from a building permit, unless the wall supports a surcharge or impounds Class I, II, or III-A liquids, per BMC 17.10.020 (Construction Administrative Code) and the Washington State Building Code (WAC 51-50 IBC / WAC 51-51 IRC). Retaining walls over 4 feet, or any wall supporting a surcharge, require a building permit and engineered design. BMC 20.30.110 (Fences) measures height for combined wall-and-fence structures from the ground level adjacent to the outside edge, so a fence built on top of a retaining wall in a required yard counts both elements toward the applicable yard height limit.

BMC 20.30.110 (Fences) does not enumerate permitted fence materials and focuses on height and location. Common materials including wood, masonry, vinyl, metal, and composite are generally allowed in residential zones subject to the yard height limits in BMC 20.30.110 and the 36-inch vision clearance triangle in BMC 20.12.060. For duplex/triplex/fourplex/townhouse/shared-court housing types under BMC 20.28.050, fences in front and side-street setbacks must be no more than 60 percent opaque and may not be chain link or cyclone fencing. Fences over 8 feet, or with masonry/concrete elements above 6 feet, must meet the 2021 IBC adopted under BMC 17.10 and WAC 51-50.

Bellingham fence heights inside a required yard are set by BMC 20.30.110 (Fences) in Title 20 Land Use Development. Fences, walls, and hedges in a required yard may not exceed: 54 inches (4.5 ft) in a front yard on an interior lot; 42 inches (3.5 ft) in a front yard on a corner lot or in a side yard on a flanking street; 72 inches (6 ft) in interior side and rear yards; and 36 inches (3 ft) inside the BMC 20.12.060 vision clearance triangle. Height is measured from the ground level adjacent to the outside edge of the wall or fence, and where a fence is constructed on top of a wall, both are included in the height calculation. Outside required yards, fences are subject to the height limits applicable to structures.

Bellingham exempts fences not over 8 feet (2,438 mm) in height that do not have masonry or concrete elements above 6 feet from a building permit, per the Construction Administrative Code adopted in BMC 17.10.020 and the Washington State Building Code (WAC 51-50). Fences over 8 feet (or with masonry/concrete elements above 6 feet) require a building permit through the Bellingham Permit Center. Land use height limits in BMC 20.30.110 apply to all fences, even those exempt from a building permit, and exceeding those height limits requires an administrative exception approved by the planning and public works directors.

Bellingham's Title 20 Land Use Code regulates fence height, location, and the vision clearance triangle, but does not impose a cost-sharing requirement on adjoining neighbors and does not include a 'finished side' rule. The City of Bellingham Permit Center publication 'Fences, Walls and Hedges' explains that fence height limits in BMC 20.30.110 apply within a required yard and that the property owner is responsible for confirming boundaries. Boundary disputes and shared-fence cost-sharing between neighbors are governed by Washington State common law and statutes (including RCW 16.60 fencing of livestock), not by the Bellingham Municipal Code.

Residential pool barriers in Bellingham follow the 2021 International Swimming Pool and Spa Code (ISPSC) adopted under BMC Chapter 17.10 and the Washington State Building Code (Chapter 51-50 WAC), effective March 15, 2024. ISPSC Section 305.2 requires a barrier not less than 48 inches above grade measured on the side of the barrier facing away from the pool, openings that do not allow passage of a 4-inch-diameter sphere, and pedestrian access gates that open outward away from the pool with a self-closing and self-latching device. Bellingham's perimeter pool fence must also satisfy the BMC 20.30.110 yard height limits (72 inches interior side/rear; 54 inches front interior lot; 42 inches corner lot or flanking street) and the BMC 20.12.060 vision clearance triangle.

Hot tubs and spas in Bellingham are governed by the 2021 International Swimming Pool and Spa Code (ISPSC) adopted under BMC Chapter 17.10 and Washington State Building Code (Chapter 51-50 WAC), effective March 15, 2024. ISPSC Section 305.6 exempts spas and hot tubs with a safety cover complying with ASTM F1346 from the barrier provisions. A building permit is required for hot tubs/spas that exceed the BMC 17.10.020 exemption (prefabricated above-ground, less than 24 inches deep, no more than 5,000 gallons, accessory to a 1- or 2-family dwelling). Electrical permits and NEC Article 680 bonding inspections are administered by Washington State L&I under WAC 296-46B.

Residential pool safety in Bellingham follows the 2021 International Swimming Pool and Spa Code (ISPSC) Section 305 as adopted under BMC Chapter 17.10 and the Washington State Building Code (Chapter 51-50 WAC), effective March 15, 2024. ISPSC Section 305.4 governs dwelling-wall doors providing direct access to the pool (alarm meeting UL 2017, ASTM F1346 powered safety cover, or self-closing/self-latching door with the release at least 54 inches above the floor). Public swimming pools are separately regulated by WAC 246-260 (Water Recreation Facilities) administered by the Washington Department of Health and locally enforced by the Whatcom County Health Department, including federal Virginia Graeme Baker Act anti-entrapment drain covers.

Residential swimming pools, hot tubs, and spas in Bellingham require a building permit from the Bellingham Permit Center under BMC Chapter 17.10 and the Washington State Building Code (Chapter 51-50 WAC, including the 2021 ISPSC) and Washington State Residential Code (Chapter 51-51 WAC, 2021 IRC), effective March 15, 2024. Prefabricated swimming pools accessory to a single- or two-family dwelling that are less than 24 inches deep, do not exceed 5,000 gallons, and are installed entirely above ground are exempt from a building permit. Electrical permits and inspections are administered by Washington State L&I under WAC 296-46B (NEC Article 680).

Residential pool, spa, and hot tub barriers in Bellingham follow the 2021 International Swimming Pool and Spa Code (ISPSC) Section 305 as adopted under BMC Chapter 17.10 and the Washington State Building Code (WAC 51-50), effective March 15, 2024. The barrier must be not less than 48 inches above grade on the side facing away from the pool, openings must not allow a 4-inch-diameter sphere to pass, the maximum vertical clearance between grade and the bottom of the barrier is 2 inches (4 inches over a solid surface), and pedestrian access gates must open outward away from the pool, be self-closing, and have a self-latching device. The perimeter pool fence must also satisfy the BMC 20.30.110 yard height limits and the BMC 20.12.060 vision clearance triangle.

Bellingham updated BMC 20.10.036 effective August 22, 2023 to pre-emptively adopt most provisions of WA HB 1337 (RCW 36.70A.680-696) before the state deadline. Up to TWO ADUs are permitted per single-family lot. A detached ADU (D-ADU) may be up to 1,000 sq ft of habitable floor area (1,800 sq ft total including ancillary space for one D-ADU; 2,000 sq ft for two attached D-ADUs). Height limit 24 ft. Setbacks 5 ft side/rear (zero from an alley). No off-street parking required within 0.5 mi of a Whatcom Transportation Authority major transit route. Bellingham was an early ADU adopter (first ordinance 1995).

Converting a Bellingham garage to habitable space requires a building permit (plus electrical, mechanical, and plumbing permits) from the Bellingham Permit Center under the 2018 Washington State Building Code (RCW 19.27). A garage-to-ADU conversion that adds a kitchen and separate entrance falls under BMC 20.10.036 ADU rules — 1,000 sq ft habitable floor max, 5 ft side/rear setbacks. Per WA HB 1337 (RCW 36.70A.681), Bellingham cannot impose an owner-occupancy mandate and cannot require off-street parking replacement within 0.5 mi of a Whatcom Transportation Authority major transit route.

BMC 20.30.100 governs accessory buildings (including sheds) in Residential Single (RS) areas: max one story or 12 ft height, max 800 sq ft area (larger only by conditional use permit), and located in the rear yard or the rear 22 ft of an interior side yard. The 2018 Washington State Building Code (RCW 19.27) — based on the 2018 IBC/IRC adopted by WAC 51-50 and 51-51 — exempts one-story detached residential accessory structures up to 200 sq ft from a building permit, provided no electrical, plumbing, or mechanical systems are added. Sheds over 200 sq ft, or any shed with utilities, require a Bellingham Permit Center building permit.

BMC 20.30.100 treats detached carports as accessory buildings in RS zones: max one story or 12 ft height, max 800 sq ft, located in the rear yard or rear 22 ft of an interior side yard. Attached carports follow the principal-building setbacks (front, side, rear) of the underlying RS or RM zone, with typical 5 ft side and 20-25 ft front setbacks per BMC 20.30.040. Construction requires a building permit from the Bellingham Permit Center under the 2018 Washington State Building Code (RCW 19.27) with engineered anchorage for Bellingham wind loads (~85-95 mph) and Seismic Design Category D2.

A tiny home on a permanent foundation in Bellingham is treated either as a primary single-family dwelling (must meet BMC 20.30.040 RS zone standards) or as an Accessory Dwelling Unit under BMC 20.10.036 (1,000 sq ft habitable floor cap, 24 ft height, 5 ft side/rear setbacks). The 2018 Washington State Building Code (RCW 19.27 + WAC 51-51, effective July 1, 2021) adopts IRC Appendix Q (Tiny Houses) — allowing reduced ceiling heights, ladder access to lofts, and small-stair geometry for homes 400 sq ft or less. Tiny homes on wheels (THOWs) registered as RVs cannot serve as a permanent residence in Bellingham residential zones.

Bellingham recreational fires are governed by the 2021 Washington State Fire Code (WAC 51-54A / 2021 IFC) adopted at BMC Chapter 17.20, plus Northwest Clean Air Agency (NWCAA) rules under WAC 173-425. The City of Bellingham allows recreational fires only when no more restrictive burn ban is in effect, the fuel is seasoned wood or charcoal, the fuel area is 3 feet or less in diameter and 2 feet or less in height, the fire is at least 25 feet from any structure or combustible material, and the fire is attended at all times until fully extinguished.

Outdoor burning of yard debris and land-clearing materials is permanently banned inside the City of Bellingham, the Bellingham Urban Growth Area, and Whatcom County Fire District 8 under Washington State law (WAC 173-425) and Northwest Clean Air Agency (NWCAA) rules. Recreational fires using seasoned wood or charcoal up to 3 feet in diameter and 2 feet in height are still allowed when no NWCAA burn ban is in effect. Burning garbage, construction or demolition material, treated wood, and yard debris is prohibited year-round.

Bellingham regulates tree removal on multiple tracks: (1) the Emergency Landmark Tree Ordinance (adopted May 20, 2024; extended through September 2026) protects any healthy tree 36 inches or greater DBH from removal without City approval, with fines of $800 to $5,000 per violation; (2) BMC Chapter 16.60 (Land Clearing) regulates 'significant trees' (6 in. DBH or greater) during development; and (3) BMC 13.40 requires a Street Tree Permit to remove any tree in a public right-of-way.

Bellingham draws its drinking water from Lake Whatcom and asks residents to follow a voluntary summer watering schedule from June 1 to September 30 to reduce stress on the supply. Even-numbered addresses water Tuesdays/Thursdays/Saturdays; odd-numbered addresses water Sundays/Wednesdays/Fridays; no watering on Mondays. The City recommends one inch per week, early morning. Washington's surface water rights are administered by the WA Department of Ecology under RCW 90.03.

Under BMC Chapter 13.40 (Street Trees and Other Vegetation), no person may perform major pruning or remove trees in planting strips, improved rights-of-way, or other public places without first obtaining a Street Tree Permit from the City. Topping is unlawful as a normal practice, and the City may require that pruning be performed by a licensed tree trimmer.