114.05    User Guide

114.10    Voluntary Provisions and Intent

114.15    Parameters for Low Impact Development

114.20    Design Standards and Guidelines

114.25    Review Process

114.30    Additional Standards

114.35    Required Application Documentation

114.05 User Guide

This chapter provides standards for an alternative type of site development that ensures low impact development (LID) principles are utilized to reduce environmental impacts on project sites in specified low density zones. If you are interested in proposing detached dwelling units or two (2) unit homes that reduce environmental impacts or you wish to participate in the City’s decision on a project including this type of site development, you should read this chapter.

(Ord. 4547 § 1, 2016; Ord. 4350 § 1, 2012)

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114.10 Voluntary Provisions and Intent

The provisions of this chapter are available as alternatives to the development of typical lots in low density zones. In the event of a conflict between the standards in this chapter and the standards in Chapters 15, 17 or 18 KZC, the standards in this chapter shall control except for the standards in Chapters 83 and 141 KZC.

The goal of LID is to conserve and use existing natural site features, to integrate small-scale stormwater controls, and to prevent measurable harm to streams, lakes, wetlands, and other natural aquatic systems from development sites by maintaining a more hydrologically functional landscape. LID may not be applicable to every project due to topography, high groundwater, or other site specific conditions.

The LID requirements in this code do not exempt an applicant from stormwater flow control and water quality treatment development requirements. LID facilities are part of those requirements, and in some cases may be all that is required.

The purpose of this chapter is to allow flexibility, establish the development guidelines, requirements and standards for LID projects. Because all projects are required to use LID principles and facilities/best management practices (BMPs) as feasible, the use of LID techniques does not necessarily fulfill all the requirements for a LID project. This chapter is intended to fulfill the following purposes:

1.    Encourage creative and coordinated site planning, the conservation of natural conditions and features, the use of appropriate new technologies and techniques, and the efficient layout of streets, utility networks and other public improvements.

2.    Encourage the creation or preservation of permanent forested open space.

3.    Manage stormwater through a land development strategy that emphasizes conservation and use of on-site natural features integrated with engineered, small-scale hydrologic controls to more closely mimic predevelopment hydrologic conditions.

4.    Minimize impervious surfaces.

5.    Encourage development of residential environments that are harmonious with on-site and off-site natural and built environments.

6.    Further the goals and the implementation of the policies of the Comprehensive Plan.

(Ord. 4547 § 1, 2016; Ord. 4350 § 1, 2012)

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114.15 Parameters for Low Impact Development

These standards and incentives address the portion of the project site utilizing the LID principles. The remainder of the project site must comply with underlying zoning and stormwater development regulations. Please refer to KZC 114.30 and 114.35 for additional requirements related to these standards.

Permitted Housing Types

Detached dwelling units.

Accessory dwelling units.

2/3 unit homes.

Minimum Lot Size

Individual lot sizes must be at least 50% of the minimum lot size for the underlying zone.

Minimum Number of Lots

4 lots.

Maximum Density

As defined in underlying zone’s Use Zone Chart or Density/Dimensions Table.

Bonus density is calculated by multiplying number of lots or units by 0.10. If a fraction of 0.5 or higher is obtained then round to the next whole number.

Low Impact Development

LID principles and facilities/BMPs must be employed to control stormwater runoff generated from all hard surfaces as feasible. This includes all vehicular and pedestrian access. LID facilities/BMPs must be designed according to Public Works stormwater development regulations as stated in Chapter 15.52 KMC.


Allowed in low density residential zones with the exception of the following:

PLA 16, PLA 3C, RSA 1, RSA 8, or the RS 35 and RSX 35 zones in the Bridle Trails neighborhood north and northeast of the Bridle Trails State Park, and the Holmes Point Overlay zone. Any property or portion of a property with shoreline jurisdiction must meet the regulations found in Chapter 83 KZC, including minimum lot size or units per acre and lot coverage.

Review Process

Short plats shall be reviewed under KMC 22.20.015 and subdivisions shall be reviewed under KMC 22.12.015.

Condominium projects shall be reviewed under KZC 145, Process I.

Parking Requirements

2 stalls per detached dwelling unit.

1 stall per accessory dwelling unit.

1.5 stalls per unit in multi-unit home, rounded to next whole number.

See KZC 105.20 for guest parking requirements.

Parking pad width required in KZC 105.47 may be reduced to 10 feet.

Parking pad may be counted in required parking.

Tandem parking is allowed where stalls are shared by the same dwelling unit.

Shared garages in separate tract are allowed.

All required parking must be provided on the LID project site.

Development Type



Minimum Required Yards (from exterior property lines)

20 feet for all front yards.

10 feet for all other required yards.

Minimum Required Yards (from internal property lines)

Front: 10 feet.

Option: Required front yard can be reduced to 5 feet, if required rear yard is increased by same amount of front yard reduction.

Side and rear: 5 feet.

Zero lot line for 2/3 unit homes between internal units.

Front Porches

Must comply with KZC 115.115(3)(n), except that front entry porches may extend to within 5 feet of the interior required front yard.

Garage Setbacks

Must comply with KZC 115.43, except that attached garages on front facade of dwelling unit facing internal front property line must be set back 18 feet from internal front property line.

Lot Coverage (all impervious surfaces)

Maximum lot coverage is the maximum lot coverage percentage of the underlying zone and may be aggregated.

Required Common Open Space (RCOS)

Minimum of 40%.

Must preserve native and undisturbed vegetation.

Allowance of 1% of required common open space for shelters or other recreational structures.

Paths connecting and within required common open space to development must be pervious.

Landscape greenbelt easement is required to protect and keep required common open space undeveloped in perpetuity.

Maximum Floor Area1

Maximum floor area is 50% of the minimum lot size of the underlying zone.


1.    The maximum floor area for LID projects in RS 35 and RSX 35 zones is 20 percent of the minimum lot size of the underlying zone.

(Ord. 4811 § 1, 2022; Ord. 4547 § 1, 2016; Ord. 4476 § 3, 2015; Ord. 4437 § 1, 2014; Ord. 4350 § 1, 2012)

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114.20 Design Standards and Guidelines

1.    Required Low Impact Development Stormwater Principles and Facilities/BMPs – Low impact development (LID) facilities/BMPs shall be designed according to Public Works stormwater development regulations, as stated in KMC 15.52.060. The maintenance of LID facilities shall be maintained in accordance with requirements in KMC 15.52.120. The proposed site design shall incorporate the use of LID strategies to meet stormwater management standards. LID is a set of techniques that mimic natural watershed hydrology by slowing, evaporating/transpiring, and filtering water, which allows water to soak into the ground closer to its source. The design should seek to meet the following objectives:

a.    Preservation of natural hydrology.

b.    Reduced impervious surfaces.

c.    Treatment of stormwater in numerous small, decentralized structures.

d.    Use of natural topography for drainage ways and storage areas.

e.    Preservation of portions of the site in undisturbed, natural conditions.

f.    Restoration of disturbed sites.

g.    Reduction of the use of piped systems. Whenever possible, site design shall use multifunctional open drainage systems such as rain gardens, vegetated swales or filter strips that also help to fulfill landscaping and open space requirements.

2.    Required Common Open Space – Required common open space shall support and enhance the project’s LID stormwater facilities/BMPs; secondarily to provide a sense of openness, visual relief, and community for low impact development projects.

a.    The minimum percentage for required common open space is 40 percent and is calculated using the size of the LID portion of the project site. Wetland and streams shall not be included in the calculation. The required common open space must be located outside of wetlands and streams. Passive trails for the residents of the development may be located in the outer 25 percent of the critical area buffer if approved under permitted activities, improvements or uses pursuant to KZC 90.40.

b.    Conventional stormwater management facilities such as vaults and tanks shall not be located within required common open space areas unless there is no other feasible alternative placement for stormwater facilities. LID facilities/BMPs are permitted, provided they do not adversely impact access to or use of the required common open space for passive recreation. Neither conventional nor LID stormwater facilities can result in the removal of healthy native trees, unless a positive net benefit can be shown and there is no other alternative for the placement of stormwater facilities. The Public Works Director must approve locating conventional stormwater facilities within the required common open space.

c.    Existing native vegetation, forest litter and understory shall be preserved to the extent possible in order to reduce flow velocities and encourage sheet flow on the site. Invasive species, such as Himalayan blackberry, must be removed and replaced with native conifers and plants (see Kirkland Native Tree and Plant List). Undisturbed native vegetation and soil shall be protected from compaction during construction. A restoration plan that achieves 80 percent coverage within two (2) years must be included with the applicant’s submittal.

d.    If no existing native vegetation, then applicant may propose a restoration plan to achieve 80 percent coverage within two (2) years that shall include all native conifer and plant species (see Kirkland Native Tree and Plant List). No new lawn is permitted and all improvements installed must be of pervious materials.

e.    Vegetation installed in required common open space areas shall be designed to allow for access and use of the space by all residents, and to facilitate maintenance needs. However, existing mature trees should be retained.

(Ord. 4551 § 4, 2017; Ord. 4547 § 1, 2016; Ord. 4437 § 1, 2014; Ord. 4350 § 1, 2012)

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114.25 Review Process

1.    Approval Process – Low Impact Development Projects

a.    The City will review and process an application for a LID project concurrent with and through the same process as the underlying subdivision proposal (Process I, Chapter 145 KZC for short plats; Process IIA, Chapter 150 KZC for subdivisions). However, public notice for LID projects shall be as set forth under the provisions of Chapter 150 KZC (Process IIA). A Process I and site plan review will be required for projects that use a condominium ownership structure and do not subdivide the property into individually platted lots.

b.    Lapse of Approval – Unless otherwise specified in the decision granting Process I approval, the applicant must begin construction or submit to the City a complete building permit application for development of the subject property consistent with the Process I approval within five (5) years after the final decision granting the Process I approval or that decision becomes void. The applicant must substantially complete construction consistent with the Process I approval and complete all conditions listed in the Process I approval decision within seven (7) years after the final decision on the Process I approval or the decision becomes void. “Final decision” means the final decision of the Planning and Building Director.

2.    Approval Process – 2/3 Unit Homes – The City will review and process a LID project application that includes a 2/3 unit home with an additional land use process as follows:

a.    One 2/3 unit home requires a Planning Official review.

b.    More than one 2/3 unit home requires a Process I review.

3.    Approval Process – Requests for Modifications to Standards

a.    Minor Modifications – Applicants may request minor modifications to the general parameters and design standards set forth in this chapter. The Planning and Building Director under a Process I, Chapter 145 KZC or Hearing Examiner under Process IIA, Chapter 150 KZC may modify the requirements if all of the following criteria are met:

1)    The site is constrained due to unusual shape, topography, easement or critical areas; and

2)    The modification is consistent with the objectives of this chapter; and

3)    The modification will not result in a development that is less compatible with neighboring land uses.

(Ord. 4749 § 1, 2021; Ord. 4551 § 4, 2017; Ord. 4547 § 1, 2016; Ord. 4350 § 1, 2012)

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114.30 Additional Standards

1.    The City’s approval of a low impact development project does not constitute approval of a subdivision or short plat. An applicant wishing to subdivide in connection with a development under this chapter shall seek approval to do so concurrently with the approval process under this chapter.

2.    To the extent there is a conflict between the standards set forth in this chapter and Title 22 of the Kirkland Municipal Code, the standards set forth in this chapter shall control.

(Ord. 4547 § 1, 2016; Ord. 4350 § 1, 2012)

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114.35 Required Application Documentation

1.     Site assessment documents to be submitted with application include:

a.    Survey prepared by a registered land surveyor or civil engineer.

b.    Location of all existing and proposed lot lines and easements.

c.    Location of all critical areas, including lakes, streams, wetlands, flood hazard areas, fish and wildlife habitat conservation areas and steep slope/erosion hazard areas.

d.    Landscape plan showing existing and proposed trees and other vegetation. The plan must show that the required common open space to be restored or augmented will be planted within native conifers and native plants to achieve 80 percent coverage within two (2) years.

2.    Soil report prepared by a licensed civil engineer, geotechnical engineer, or engineering geologist.

3.    Stormwater drainage report/technical information report.

(Ord. 4551 § 4, 2017; Ord. 4547 § 1, 2016; Ord. 4350 § 1, 2012)

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