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A. General.

1. Purpose. The purpose of this section is to allow for the continuance and maintenance of legally established nonconforming structures, sites, lots and uses, and to provide standards delineating the circumstances in which nonconforming structures, sites, lots and uses must be brought into conformance with the provisions of all applicable code requirements.

2. Legal Nonconforming Status of Structures, Sites and Uses. All structures, sites and uses that lawfully existed prior to September 26, 1960, shall be considered legally nonconforming. Structures, sites and uses that were constructed or initiated after September 26, 1960, that were in conformance with all applicable code provisions in effect at the time of their creation but are not in compliance with current land use codes as a result of subsequent changes in code requirements are deemed to be legally nonconforming structures, sites and uses.

3. Illegal Nonconformance of Structures, Sites and Uses. Structures, sites and uses that were not in conformance with all applicable code provisions in effect at the time of their creation are illegal and shall be brought into compliance with all applicable provisions of this code.

4. Continuation or Loss of Legal Nonconforming Status of Structures, Sites and Uses. A structure, site or use may be maintained in legal nonconforming status as long as no new nonconformances are created, there is no expansion of any existing nonconformity, and legal nonconforming status is not lost under any of the circumstances set forth in this section. If legal nonconforming status is lost, the structure, site or use must be brought into conformance with all applicable code requirements.

5. Critical Areas. This section shall govern nonconforming structures, sites, lots and uses within any critical area, unless Chapter 19.07 MICC, Critical Lands, establishes more specific standards.

6. Application of Codes. Nothing in this section in any way supersedes the requirements of the construction codes set forth in MICC Title 17, and any other construction-related codes as adopted and amended from time to time by the city.

7. Deviations. Existing structures and sites resulting from the approval of a previous deviation shall be considered “conforming” structures or sites, provided the structure or site complies with the deviation approval.

B. Repairs and Maintenance.

1. Ordinary Repairs and Maintenance. Ordinary repairs and maintenance of a legally nonconforming structure are permitted. In no event may any repair or maintenance result in the expansion of any existing nonconformity or the creation of any new nonconformity.

2. Decks. Repair and maintenance of a legally nonconforming deck, including total replacement, are allowed, as long as there is no increase in the legal nonconformity and no new nonconformances are created; provided, any portion of a nonconforming deck that is in a side yard and less than five feet from an interior lot line may be replaced only if the deck is reconstructed to comply with current minimum side yard requirements.

C. Interior Remodel. Interior remodeling of a legally nonconforming structure is permitted and will not result in loss of legal nonconforming status regardless of the cost or extent of the interior remodel, as long as no exterior alteration or enlargement is involved. If exterior alteration in conjunction with interior remodeling is involved, loss of legal nonconforming status will be determined pursuant to the provisions set forth in subsection D of this section.

D. Exterior Alteration or Enlargement of Nonconforming Structures.

1. Detached Single-Family Residential Structures.

a. Reconstruction Following Catastrophic Loss. Any legally nonconforming detached single-family dwelling and/or accessory building or structure that suffers a catastrophic loss shall not lose its legal nonconforming status. Such dwelling or accessory building or structure may be reconstructed regardless of the extent of damage or reconstruction cost, to re-establish the previous legal nonconformity or otherwise, as long as there is no expansion of any existing nonconformity, the reconstruction creates no new nonconformance, and a complete building permit for reconstruction is submitted to the city within 12 months of the date of the loss.

b. Intentional Exterior Alteration or Enlargement.

i. Detached Single-Family Dwelling. A legally nonconforming detached single-family dwelling may be intentionally altered or enlarged without losing its legal nonconforming status as long as no more than 40 percent of the length of the dwelling’s existing exterior walls, excluding attached accessory buildings, is structurally altered. Any portion of the length of existing walls that is structurally altered shall be included in calculating the 40 percent threshold. In no event shall the alteration or enlargement increase any existing nonconforming aspect of the dwelling or create any new nonconformance. Legal nonconforming status shall be lost, and the structure shall be required to come into conformance with current code requirements, if the 40 percent threshold is exceeded. An increase in height of that portion of a structure that is legally nonconforming because it intrudes into a required yard is an increase in the nonconformity and is not allowed unless the additional height meets the current yard requirements of MICC 19.02.020(C)(1) except:

(a) A change from a flat roof to a pitched roof is allowed under MICC 19.02.020(C)(3)(a); and

(b) A height increase of a single-family dwelling and any accessory building or structure in the R-8.4 zone that is legally nonconforming because it intrudes into a minimum five-foot required side yard is allowed only if the additional height is modulated so that it is a minimum of 10 feet from the side yard property line.

ii. Accessory Buildings or Structures. A legally nonconforming attached or detached accessory building or structure, including but not limited to a carport, garage, shed, gazebo, deck or fence, may be altered or enlarged without losing its legal nonconforming status as long as no more than 40 percent of its existing exterior perimeter (or length in the case of a fence) is structurally altered. A wall that is shared with the main dwelling shall not be included in the calculation for the attached accessory building. In no event shall any alteration or enlargement increase any existing nonconforming aspect of the building or structure or create any new nonconformance. Legal nonconforming status shall be lost, and the structure shall be required to come into conformance with current code requirements, if the 40 percent threshold is exceeded.

iii. Structural Alteration Calculation. For the purposes of determining the percentage of exterior walls of a nonconforming structure that is being structurally altered, the following calculation applies:

Formula:

Percentage of exterior walls altered = (sum of the length of existing exterior walls to be structurally altered) ÷ (sum of the length of existing exterior walls)

Where:

(a) The “sum of the length of existing exterior walls to be structurally altered” is the sum of each wall segment that is completely demolished.

(b) The “sum of the length of exterior walls” is the sum of the lengths of each exterior wall segment of a structure or building.

(c) For the purposes of this subsection, a wall segment is “completely demolished” when any portion of the wall is completely removed, such that no structural elements remain.

(d) For the purposes of this subsection, the “wall segment” is the horizontal length of each continuous exterior wall plane or façade; provided, that each building modulation (e.g., a bay window bump-out) shall be accounted for as a separate exterior wall plane. For example, the sum of the length of the exterior wall segments for a building that is a perfect cube with a dimension of 50 horizontal feet on each side of the house is 200 feet. The same building with a second story bay window bump-out dimensioned two feet by 10 feet by two feet has a sum of 214 feet.

iv. Roof Repair and Replacement. The roof of a nonconforming structure may be repaired including total replacement; provided, that there is no expansion of any existing nonconformity. Repair or replacement of a roof does not constitute structural alteration of exterior walls.

v. Cumulative Time Limit. The maximum cumulative structural alteration of a legally nonconforming structure, as described in subsections (D)(1)(b)(i) and (ii) of this section, is 40 percent within any five-year period. The five-year period includes the cumulative total of the work authorized by a permit application, and the work conducted within the five years immediately prior to demolition or construction authorized by the permit application. Legal nonconforming status shall be lost, and the structure shall be required to come into conformance with current code requirements, if the cumulative 40 percent threshold is exceeded within the five-year time limit.

2. Town Center.

a. Reconstruction Following Catastrophic Loss. In the Town Center, a legally nonconforming structure which suffers a catastrophic loss may be reconstructed to its previous legally nonconforming configuration and appearance if the cost of the reconstruction equals or is less than 75 percent of the structure’s current King County assessed value as of the time the loss occurs and is reconstructed within the same building footprint, to the same number of stories, and to the same square footage of the legally nonconforming damaged or destroyed structure. If the damaged or destroyed portion of the structure is reconstructed to other than its previous nonconforming configuration and appearance, the entire structure shall lose its nonconforming status and shall be required to come into conformance with current code requirements; however, minor changes in appearance that bring it into closer conformity with current code requirements shall not result in overall loss of nonconforming status. In any event, if the 75-percent threshold is exceeded, legal nonconforming status shall be lost and the structure shall be required to come into conformance with current code requirements.

b. Intentional Exterior Alteration or Enlargement. Legal nonconforming status of a structure in the Town Center is lost, and the structure shall be required to come into conformance with current code requirements, if there is any intentional exterior alteration or enlargement of a structure that costs in excess of 50 percent of the structure’s current King County assessed value as of the time the initial application for such work is submitted. No structure may be altered or enlarged so as to increase the degree of nonconformity or create any new nonconformance.1

3. Nonconforming Structures Other Than Single-Family or in Town Center.

a. Reconstruction Following Catastrophic Loss. Any legally nonconforming structure not covered under subsections (D)(1) or (2) of this section, that suffers a catastrophic loss may be reconstructed to its previous legally nonconforming configuration regardless of the extent of damage or reconstruction cost. No structure may be reconstructed so as to increase the degree of its nonconformity or create any new nonconformance. Regulated improvements reconstructed to their previous legally nonconforming configuration shall be subject to partial design review as provided by MICC 19.12.010(D)(2); however, no condition may be imposed by the design commission or code official which would have the effect of reducing the number of units contained in a multiple-family dwelling prior to the catastrophic loss.

b. Intentional Exterior Alteration or Enlargement. Legal nonconforming status of any legally nonconforming structure not covered under subsection (D)(1) or (2) of this section is lost, and the structure and site shall be required to come into conformance with all current code requirements, including design review, if there is an intentional exterior alteration or enlargement of the structure over any three-year period that incurs construction costs in excess of 50 percent of the structure’s current King County assessed value as of the time the initial application for such work is submitted; provided, application of this subsection shall not be construed to require an existing structure to be demolished or relocated, or any portion of an existing structure that is otherwise not being worked on as part of the construction to be altered or modified. If there is no current King County assessed value for a structure, a current appraisal of the structure, which shall be provided by the applicant and acceptable to the code official, shall be used as the value point of reference. No structure may be altered or enlarged so as to increase the degree of nonconformity or create any new nonconformance.

E. Abandonment of a Legally Nonconforming Structure or Use.

1. Structure. A legally nonconforming structure shall be deemed to be abandoned, and shall lose its legal nonconforming status and be required to come into conformance with current code requirements, after the structure has been unoccupied continuously for 12 months or more, unless it is listed on the state or federal register of historic buildings or meets the criteria for a historic building pursuant to Chapter 16.01 MICC.

2. Use. A legally nonconforming use shall be deemed to be abandoned and shall lose its legal nonconforming status, and any subsequent use shall be required to conform with current code requirements, after the use has been discontinued for 12 consecutive months or more.

3. Exception. A structure that has been unoccupied continuously for 12 months or more, or a use that has been discontinued for 12 consecutive months or more, shall not be deemed abandoned if the owner of the structure can provide compelling evidence, to the satisfaction of the code official, that the structure is being actively marketed for sale or the owner of the structure otherwise has a reasonably timely and viable plan for resuming occupation of the property or resuming the legally nonconforming use.

F. Nonconforming Sites.

1. Impervious Surface Coverage Limitation. A structure on a site that is legally nonconforming because the maximum allowable surface coverage has been exceeded can be increased in height and gross floor area (up to the maximum permitted). No new impervious surfaces are permitted outside the footprint of an existing structure unless the site is either brought into conformance with all applicable impervious surface limitations or two square feet of legally existing impervious surface are removed for every one square foot of new impervious surface.

2. Parking Requirements. These parking requirements apply to subsections (F)(2)(a) and (c) of this section in the event of an intentional exterior alteration or enlargement, but do not apply in the event of reconstruction following a catastrophic loss. In the event of catastrophic loss, nonconforming parking may be restored to its previous legally nonconforming configuration.

a. Detached Single-Family Dwelling Site. A proposed addition of more than 500 square feet of gross floor area to a detached single-family dwelling site, which is legally nonconforming because it does not provide the number and type of parking spaces required by current code provisions, shall provide parking spaces as provided by MICC 19.02.020(G).

b. Town Center. A structure in the Town Center that is legally nonconforming because it does not provide the number and type of parking spaces required by current code provisions shall provide parking spaces as required by MICC 19.11.130(B)(1)(a) and subsections (I)(1) and (2) of this section, as applicable.

c. Sites Other Than for a Detached Single-Family Dwelling or in Town Center.

i. New Development and Remodels. A site other than those identified in subsections (F)(2)(a) and (b) of this section that is legally nonconforming because it does not provide the number or type of parking spaces required by current code provisions shall provide parking spaces as required by the current code provisions for the zone where the site is situated for all new development and remodels greater than 10 percent of the existing gross floor area.

ii. Change of Use. A site other than those identified in subsection (F)(2)(a) and (b) of this section that is legally nonconforming because it does not provide the number or type of parking spaces required by current code provisions shall provide parking spaces as required by the current code provisions for the zone where the site is situated whenever there is a change of use.

3. Landscaping, Open Space and Buffer Requirements.

a. Regulated Improvements. A site developed with a regulated improvement shall be brought into conformance with current code requirements for landscaping, open space and buffers, whenever a structure or use on the site loses its legal nonconforming status. Landscaping, open spaces and buffers should be brought into conformance with current code requirements as much as is feasible whenever any changes are made to a legal nonconforming structure.

b. Lot Coverage – Single-Family Dwellings. A site developed with a single-family dwelling that is legally nonconforming because the required landscaping area pursuant to Chapter 19.02 MICC has not been provided, or because maximum allowable hardscape has been exceeded, can be increased in height and gross floor area (up to the maximum height and gross floor area permitted). No new hardscape or further reduction in landscaping area is permitted unless:

i. The site is either brought into conformance with all applicable lot coverage requirements of MICC 19.02.020; or

ii. For lots where the maximum hardscape is exceeded, two square feet of legally existing hardscape are removed for every one square foot of new hardscape; or

iii. For lots where the maximum lot coverage is exceeded, two square feet of landscaping area are provided for every one square foot of additional nonlandscaping area.

G. Nonconforming Lots.

1. Legally Nonconforming Lot. A nonconforming lot shall be deemed to be a legally nonconforming lot if the lot was legally created. In order to establish that a lot was legally created, an applicant seeking permit approval must provide:

a. A long subdivision, short subdivision or plat approved by the city of Mercer Island or King County, separately describing and creating the lot in question; or

b. A deed, contract of sale, mortgage, property tax segregation, or recorded survey separately describing and/or conveying the lot in question if the instrument was executed prior to July 18, 1960, and evidence that the creation of the lot was consistent with all codes in effect at the time of such conveyance or recording date.

2. Illegal Nonconforming Lot. A lot which was not legally created in accordance with the laws of the local governmental entity in which it was located at the date of its creation is an illegal nonconforming lot and will not be recognized for development.

3. Minimum Requirements for Development of Legally Nonconforming Lot. In order to be used as a building site, an undeveloped legally nonconforming lot must meet the following minimum requirements:

a. The lot must exceed 3,500 square feet;

b. The lot must have a minimum width of 30 feet and a minimum depth of 50 feet;

c. The property owner must provide evidence that establishes that the lot was intended to be a building site at the time of its creation; and

d. The lot must not be subject to consolidation pursuant to subsection (G)(5) of this section.

If the owner provides proof to the satisfaction of the code official, demonstrating that the strict application of subsections (G)(3)(a) through (d) of this section prevents all reasonable use of the lot and that the owner was not involved in the creation of the legal nonconformity, such owner may be permitted to use the lot for one single-family residential dwelling, even if the lot does not meet the size, width, depth and other dimensional requirements of the zone, as long as all other applicable site, use and development standards are met or a variance from such site use or development standards has been obtained.

4. Development of Legally Nonconforming Lot. Subject to the limitations of subsections (G)(3) and (5) of this section, a legally nonconforming lot may be developed for any use allowed by the zoning district in which it is located, even though such lot does not meet the size, width, depth and other dimensional requirements of the zone, as long as all other applicable site, use and development standards are met or a variance from such site use or development standards has been obtained.

5. Consolidation. If, since the date on which it became nonconforming due to its failure to meet minimum lot size or width criteria, a legally nonconforming lot has been in the same ownership as a contiguous lot or lots, the nonconforming lot is and shall be deemed to have been combined with such contiguous lot or lots to the extent necessary to create a conforming lot and thereafter may only be used in accordance with the provisions of this code, except as specifically provided in subsection (G)(6) of this section.

6. Continuation of Developed Legally Nonconforming Lot. A legally nonconforming lot that was developed as a separate and complete building site in accordance with the applicable laws at the time of development shall maintain its legal nonconforming status even if the lot has been in the same ownership as a contiguous lot or lots; provided, if separately developed, contiguously owned legally nonconforming lots are subsequently developed as one building site, the lots shall be deemed to be consolidated and may only be used as a single lot thereafter.

7. No New Nonconformities Created. No nonconforming structure, site, lot or use shall be created as a result of the division of land or any modification of a lot line through any subdivision or lot line revision pursuant to Chapter 19.08 MICC.

H. Nonconforming Uses.

1. Change of Use. Any change from a legal nonconforming use shall be to a conforming use only; provided, the continuation of the same or similar use by the same or different owner will not result in loss of legal nonconforming status.

2. Additional Uses Prohibited. While a legal nonconforming use exists on any lot, no separate or new use may be established thereon, even though such additional use would be a conforming one.

3. Expansion of Legal Nonconforming Use. Legal nonconforming uses shall not be expanded or enlarged; however, if the code official determines that expansion or enlargement of the use or an accessory use (including parking) or other site modifications would make the use more conforming to current code standards or is required by city ordinance, state law, or federal law and no new nonconformity is created it may be allowed. Expansion includes increasing the size of the structure in which the use occurs or enlarging the scope, volume, area or intensity of the use in a significant way.

4. Nonconforming Use Associated With Structure that Suffers Catastrophic Loss. In the event of catastrophic loss to a structure, the legal nonconforming status of any use contained in the structure shall not be lost, provided a complete building application to rebuild the structure and reestablish the nonconforming use is submitted within 12 months of the loss.

I. Change of Use – Town Center.

1. Single Tenant. If any applicant proposes a change of use on a lot used or occupied by a single tenant or use, the applicant shall meet those code provisions determined by the code official to be reasonably related and applicable to the change in use. These provisions shall apply to the entire lot. If the development is nonconforming due to the number of parking spaces provided for the existing use, any change in use which requires more parking than the previous use shall provide additional parking consistent with current code parking requirements.

2. Multi-Tenant. If any applicant proposes a change of use on a portion of a lot occupied by multiple tenants or uses, the applicant shall meet those code provisions determined by the code official to be reasonably related and applicable to the change in use. These provisions shall apply only to that geographic portion of the lot related to the use or tenant space on which the change is proposed. If the multi-tenant lot is nonconforming due to the number of parking spaces provided for the existing uses, any change in use, which requires more parking than the previous use, shall provide additional parking consistent with current code parking requirements.

J. Enforcement. The provisions of this section requiring compliance with current code requirements for any illegal nonconforming structure, site or use, for any legally nonconforming structure, site or use that loses its nonconforming status and for any structure or use that is deemed abandoned shall be enforced pursuant to the provisions of Chapter 6.10 MICC.

1Code reviser’s note: MICC 19.01.050(D)(2)(c) has been deleted as obsolete, per the city’s request, as a scrivener’s error.

(Ord. 19C-04 § 1 (Exh. A); Ord. 17C-15 § 1 (Att. A); Ord. 16C-06 § 3 (Exh. A); Ord. 11C-08 § 1; Ord. 04C-12 § 8; Ord. 04C-08 § 5; Ord. 03C-01 § 2).