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The regulations in this section shall apply to accessory dwelling units (ADUs), whether attached or detached to a single-family housing unit, duplex, triplex or townhome. The term “ADU” as used in this section shall apply to either attached or detached accessory dwelling units. The term “DADU” as used in this section shall apply only to detached accessory dwelling units. In the event there is a conflict between the provisions of this section or any other provision of the EMC, the provisions of this section shall control.

A. General Standards. The following table is a summary of the standards required for ADUs in the single-family (SF) zones (R-S, R-1, R-2, R-2(A)), and within the UR3 zone if within an area designated as an Everett historic district or historic overlay:

Table 8-6: ADU Standards



1)    Owner Occupancy:

a)    R-S, R-1, and R-2 zones: One of the units must be owner-occupied.

b)    Other zones: Owner occupancy not required.

2)    Lot Requirements:

a)    No minimum lot size required.

b)    Only one ADU per lot.

c)    An ADU may not be segregated from ownership of the principal dwelling.

3)    ADU Size:

a)    Single-family dwelling unit: An ADU attached or detached from a single-family dwelling unit shall not exceed a gross floor area the lesser of 1) 15% of the total lot area; 2) 1,000 square feet; or 3) the principal dwelling’s building footprint.

b)    Duplex, triplex or townhome: An ADU attached or detached from a duplex, triplex or townhome shall not exceed a gross floor area the lesser of 1) 7.5% of the total lot area; 2) 1,000 square feet; or 3) 37.5% of the gross floor area of the dwelling; provided, however, that an ADU is permitted to be no less than 440 square feet.

4)    Lot Coverage:

a)    See applicable zone (Chapter 19.06 EMC).

b)    An increase of 5% may be allowed, using Review Process I, if necessary to allow a DADU on an existing developed lot that meets all other requirements of this section.

5)    Maximum Height:

See Chapter 19.22 EMC.

6)    Setbacks:

See Chapter 19.06 EMC.

7)    Vehicle Access:

See city standards in EMC Title 13 and Chapter 19.34 EMC.

8)    Historic Overlay:

Any ADU located within an historic overlay zone must also comply with the design requirements of the historic overlay and be reviewed by the city’s historical commission with a recommendation to the planning director.

B. Design Standards. An ADU shall meet the design standards in this section. The planning director shall consider the impact that any requested modification will have on abutting properties in terms of aesthetics, privacy, view impacts, and compatibility with the character of other dwellings.

1. Attached ADUs. The appearance and character of the dwelling shall be maintained when viewed from the surrounding neighborhood.

a. Single-Family (One-Unit) and Townhouse Dwellings. Only one entrance to the residential structure may be located on any street side of the structure; provided, however, that this limitation shall not affect the eligibility of a residential structure which has more than one entrance on the front or street side on the effective date of the ordinance codified in this section.

b. Duplex and Triplex (Two- and Three-Unit) Dwellings. Any ADU attached to a two- or three-unit dwelling shall comply with the front porch and entrance requirements set forth in EMC 19.08.050.

2. Historic Overlay Zones. On lots located in the historic overlay zone, an attached ADU shall comply with the standards of subsection (B)(1) of this section. A DADU shall comply with the development and design standards of the H overlay zone.

3. Detached ADUs. The planning director shall promulgate a design manual of examples and best practices for the design of DADUs and compatibility with the surrounding neighborhood. The city shall have the authority to require changes to the design of a DADU that is not consistent with best practices identified in the design manual. In addition:

a. The DADU shall be designed to give the appearance that it is secondary to the principal dwelling.

b. Siding, roofing, windows and building trim materials shall visually match those used on the principal dwelling.

c. The roof pitch shall be similar to the predominant roof pitch on the principal dwelling.

C. Owner Occupancy, When Required.

1. Either the principal dwelling unit or the ADU shall be occupied by the owner of the property as his or her principal residence when located within the R-S, R-1, or R-2 zones.

2. When required, prior to issuance of a permit for an accessory dwelling unit, the property owner shall submit to the city a signed affidavit affirming that the owner occupies the principal dwelling as his or her principal residence and will occupy either the principal dwelling or accessory dwelling after completion of the accessory dwelling unit.

3. When required, the owner shall record a covenant with the Snohomish County auditor, approved by the director, that shall run with the land as long as the ADU is maintained on the property. The property owner shall submit proof that the covenant has been recorded with the Snohomish County auditor’s office prior to issuance of the building permit.

4. When required, the property owner shall certify to the city no later than April 1st of each year that the owner occupies one of the dwellings as the owner’s principal residence. Any person who fails to report or falsely certifies residence in a dwelling unit at the stated address shall be subject to the enforcement and penalty provisions of Chapter 1.20 EMC.

D. Modification of Standards. A property owner may request that the planning director modify the design standards, using Review Process II as set forth in EMC Title 15 and criteria set forth in Chapter 15.03 EMC. (Ord. 3901-22 § 2 (Exh. B § 45), 2022; Ord. 3774-20 § 5(G) (Exh. 3), 2020.)