Mountlake Terrace City Zoning Code

Residential 1 (R-1). The purpose of the residential 1 land use designation is to provide land for detached single-unit residences, duplexes, and other complementary uses, while encouraging a clean and healthy environment, safety, walkability, neighborliness, affordability for a range of income levels, and adequate open space.

Residential 2 (R-2). The purpose of the residential 2 land use designation is to provide land for detached single-unit residences, duplexes, triplexes, fourplexes, other middle housing types up to four units, and other complementary uses, while encouraging a clean and healthy environment, safety, walkability, neighborliness, affordability for a range of income levels, and adequate open space.

Residential 3 (R-3). The purpose of the residential 3 land use designation is to provide land at efficient densities for all middle housing types and other complementary uses, while still allowing for detached single-unit residences, and encouraging a clean and healthy environment, safety, walkability, neighborliness, affordability for a range of income levels, and convenient access to public transit. These lots serve as a transitional zone between the predominately detached single-unit residences, and the denser multifamily developments of residential 4.

Residential 4 (R-4). The purpose of the residential 4 land use designation is to provide land at efficient densities for middle housing, multifamily residences, and other complementary uses, while still allowing for detached single-unit residences, and encouraging a clean and healthy environment, safety, walkability, neighborliness, affordability for a range of income levels, and convenient access to public transit. These lots serve as a transitional zone between the other residential land use designations, and denser mixed-use developments.

Development standards in this chapter are applicable to all development in the residential districts, as well as to any middle housing or single-unit development in other districts.

Nonconforming Structures. Structures that no longer comply with development standards as of June 30, 2025, are allowed. Only in the case of loss of the structure due to fires or other natural disasters may the structure be rebuilt within 12 months to the preexisting nonconforming standards.

Allowable uses within the R districts are identified in Table 19.30.020 below, as now or hereafter amended.

Permitted Use (P). Where the letter "P" appears in the box at the intersection of the column and the row, the use is allowed in that district subject to applicable conditions or other standards (if any) listed in the "conditions/reference" column to the right and the review procedures specified in MTMC Title 18, Land Use Planning and Development, and the general requirements of the code.

Conditional Use (C). Where the letter "C" appears in the box at the intersection of the column and the row, the use is allowed subject to applicable conditions or other standards (if any) listed in the "conditions/reference" column to the right and to the conditional use review procedures specified in MTMC Title 18, Land Use Planning and Development, and the general requirements of the code.

Use Not Permitted (). Where no symbol appears in the box at the intersection of the column and the row, the use is not allowed in that district, except for certain temporary uses.

For uses containing a superscript number^(X), refer to the applicable condition in the "conditions/reference" column to the right.

Dimensional requirements, as identified in this section, shall apply to all buildings and lots in the R districts, except as otherwise specifically provided by this chapter.

Dimensional requirements for lots and buildings in R districts are set forth in the following dimensional requirements table; provided, that lesser areas or distances may be allowed subject to meeting the requirements of MTMC § 19.30.035, as applicable, or as otherwise specifically allowed under this title or MTMC Title 17 and greater areas or distances may be specifically required under certain provisions of the MTMC.

The lot dimensional requirements in MTMC § 19.30.030 apply to the parent lot, not the smaller "unit lots" created in a unit lot subdivision.

Regardless of the minimum lot area required under MTMC § 19.30.030, a subdivision may include one lot that does not meet minimum lot requirements; provided, that the lot would have an area that is at least 90 percent of the required minimum lot area of the underlying district and would meet all other dimensional requirements of MTMC § 19.30.030C.

Building height is regulated in both front and rear portions of the lot. "Building height at front of lot" is measured in the front 75 percent of mean lot depth. "Building height at rear of lot" is measured in the rear 25 percent of mean lot depth.

A manufactured home shall be permitted to locate on any residential lot when it meets the development standards of this title and all other applicable regulations for single units are met.

Accessory dwellings shall comply with MTMC § 19.30.050, as now or hereafter amended.

Accessory buildings (nonresidential) shall comply with MTMC § 19.120.130.

Animals are allowed subject to the provisions of MTMC Title 6.

A storage building for a legally established nonresidential use may be permitted under the following conditions: (1) it is on the same lot as the nonresidential use; (2) it is constructed of materials similar to the building that comprises the primary nonresidential use on the lot; and (3) it is for a purpose that is consistent with the residential character of the neighborhood.

The locational and area standards of this chapter and of any other regulations in this title pertaining to development under this chapter do not have to be met on individual lots, parcels or tracts developed under the provisions of Chapter 17.09 MTMC, Fee Simple Unit Lot Subdivisions; provided, that they are met on the collective lots, parcels and/or tracts in a fee simple unit lot subdivision and that all standards otherwise applicable to the outer perimeter of individual lots (e.g., setbacks, landscaping and buffers) are met around the outer perimeter of the fee simple unit lot subdivision.

Applicability. Within residential districts, development standard bonuses are available for developments that provide specific public benefits outlined in this section. In exchange for the specified public benefits, the project can utilize the development standards bonuses described in Table 19.30.030. The bonuses have been crafted to offer value to middle housing development, while achieving the intended public benefits while maintaining compatibility with neighborhood scale and residential patterns. Multiple bonuses may be combined on a site, subject to the standards in Table 19.30.030.

Purpose. The bonus program aims to go beyond the typical benefits of middle housing by incentivizing additional contributions aligned with community priorities and Comprehensive Plan Vision 2044 goals. The program focuses on the following public benefits:

Affordable Housing Bonus. A development may receive bonuses (increased lot coverage, FAR, height, and setback reductions per Table 19.30.030) for providing affordable housing consistent with Chapter 3.96 MTMC at the following minimum amounts:

On-Site Tree Retention Bonus. A development may receive bonuses (increased lot coverage, FAR, height, and setback reductions per Table 19.30.030) for providing on-site tree retention. Eligible projects must:

Sustainability Certification Bonus. A development may receive bonuses (increased lot coverage, FAR, height, and setback reductions per Table 19.30.030) for providing sustainability certification. To be eligible for the bonus, new developments and major renovations shall be designed, constructed, and certified to meet or exceed standards of one or more of the following rating systems:

Alleys. A development may receive bonuses (increased lot coverage, FAR, height, and setback reductions per Table 19.30.030) for providing alleys or portions of alleys at the rear of the lot. Eligible alleys must meet the following criteria:

Midblock Connections. A development may receive bonuses (increased lot coverage, FAR, height, and setback reductions per Table 19.30.030) for providing midblock connections. Midblock connections must meet the following criteria:

Improved Parking Courts. A development may receive bonuses (increased lot coverage, FAR, height, and setback reductions per Table 19.30.030) for providing improved parking courts. They may not count towards required open space. Improved parking courts must meet the following criteria:

Shared Driveways. A development may receive bonuses (increased lot coverage, FAR, height, and setback reductions per Table 19.30.030) for providing shared driveways. Shared driveways must provide access to (1) parking garages; or (2) lots containing four or more stalls; or (3) on abutting parent lots greater than 14,000 square feet.

The intent of this section is to:

Accessory dwelling units are permitted on a lot, provided the following requirements are met:

Accessory dwelling units shall comply with all standards for health and safety as provided in Chapter 15.05 MTMC, as now or hereafter amended, and any other applicable chapters of this code, except as specifically granted otherwise.

Permitting. An accessory dwelling unit shall not be permitted unless the property owner has applied for and been issued a building permit by the Department.

Elimination of an accessory dwelling unit may be accomplished by the property owner recording with the Snohomish County Auditor's office a certificate identifying the property's address and that the accessory dwelling unit no longer exists on the property, and providing a copy of the certificate to the City.

Hours of operation for outdoor activities shall not extend into nighttime hours when sounds can be declared a nuisance affecting public peace, referenced in Chapter 8.20 MTMC.

Outdoor recreation facility lighting shall be turned off during nighttime hours, referenced in Chapter 8.20 MTMC.

Light fixture height maximum shall be determined based on recreation use and addressed through the conditional use permit review process.

All lights provided to illuminate parking areas, buildings, and outdoor facilities shall be shielded and arranged to direct light away from any adjoining properties in accordance with MTMC § 19.120.030.

Fences must comply with MTMC § 19.120.200. The first 12 feet in height (ground up to 12 feet) of fencing shall be site obscuring. For example, chain-link fencing with slats, mesh, or solid wood fencing would be considered appropriate.

Traffic impact analysis (TIA) is required each time a private recreation facility is proposed in a single-unit residential zone as part of the conditional use permit review.

A minimum of one off-street loading/unloading space shall be provided, subject to MTMC § 19.125.080.

On interior and through lots, the required side yards may be used to provide off-street parking areas and, on corner lots, the rear yard may be used. The required front yard may not be used for off-street parking.

All structures shall be set back 20 feet from property lines.

Buildings associated with private recreation facility uses shall not exceed 35 feet in height as defined in Chapter 19.15 MTMC.

The minimum lot area required to locate a private recreation facility is one and one-half acres. The maximum lot size to locate a private recreation facility is three acres.

For private recreation facility uses, the maximum lot coverage by structures required is 45 percent of lot area.

For private recreation facility uses, the maximum impervious surface allowed is 75 percent.

Outdoor open space must be provided consistent with the following:

Common and private open space must conform to the design standards in MTMC § 19.32.020G.

Neighborhood commercial services in any single building shall not exceed a total of 5,000 square feet in area unless approved up to 10,000 square feet in area under a conditional use permit. A "single building" for this purpose shall include any buildings that are located on the same lot and connected by a walkway or driveway outside of a public right-of-way or by a building element.