PRESENTATION: NET DENSITY & GROSS DENSITY

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City of Ferndale

CITY COUNCIL STAFF REPORT

MEETING DATE: September 2, 2020 AGENDA BILL #__________

SUBJECT: Density Presentation DATE: September 2, 2020 FROM: Haylie Miller PRESENTATION BY: Haylie Miller

EXHIBIT 1: Comprehensive Plan EXHIBIT 2: Zoning Map EXHIBIT 3: Douglas Place Long Plat Div. 3 RECOMMENDATION: No recommendation is provided, and no Council action is required. This topic will be presented to the Planning and Land Use Committee on September 2, 2020 for informational purposes only. The City Council is encouraged to ask questions on this topic or request additional information if needed. BACKGROUND: The City of Ferndale’s Comprehensive Plan (Exhibit 1) is divided into seven distinct land use classifications including: Commercial, Industrial, Low Density Residential, Medium Density Residential, High Density Residential, Residential-Unspecified, and Public. Each land use designation is further divided into fourteen distinct zoning districts (Exhibit 2 – Zoning Map). The City of Ferndale regulates densities in zones that allow residential uses1 based on the number of dwelling units per Net or Gross property area. This regulation is also accompanied with an established minimum and/or maximum density for that zone. Unlike commercial or industrial uses, which tend to lack a uniform method of measuring the intensity of development, the intensity of residential uses are measured by "density," generally expressed as the number of residential "units" in a given area. Most often, density is measured per acre (43,560 square feet), and utilizing either a net or gross calculation, as will be discussed in greater detail below

1 The City Center, Urban Residential, RS Low-Single Family Dwelling, RS Medium Single Family

Dwelling, RS High Single Family Dwelling, Residential Multifamily Medium, Residential Multifamily

High, Residential Office and the Mixed Use Commercial Zones allow for residential Uses (See Exhibit 1 –

Zoning Map).

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In general, the City’s commercial zones do not establish ratios or minimum amounts of commercial uses required, with exception of the Mixed-Use Commercial Zone. In general, the intensity of commercial use that could be placed on a parcel will be dictated by the setbacks, building height, parking requirements, stormwater approached, site conditions and other zoning or development regulations, in addition to market and an applicant’s financial conditions2. This staff report is intended to provide an overview of the concept of density including how it is calculated and which types of density calculations are used in each zone in the City. DENSITY CALCULATIONS: Gross Density Gross density means the number of residential units per acre of land. This is calculated by taking the total lot area divided by the number of units. For example: if a ten-acre property contains 40 residential lots, the gross density is 4 units per acre (40-units/10-acres = 4 units/acre). Net Density Net Density is defined as the number of units (typically expressed in residential units) per acre of land after required infrastructure and critical areas are deducted from the gross area – thus leaving only the area devoted to the lots themselves. In many cases, net density may be calculated by adding the cumulative area of all lots together and dividing that sum by the number of lots in a given area, typically within one subdivision. “Required infrastructure and critical areas” includes, but is not limited to, required public or private roads, infrastructure such as stormwater ponds, required public parks or trails, critical areas, and their required buffers. The net density calculation typically computed when a lot design proposal is submitted. For example: if a ten-acre property lot has one acre of wetlands, 0.5-acres of roadways, a 0.25-acre storm pond, a 0.25 acre park and 0.5 acres of open space tracts, the remaining “Lot Area” after subtracting the various infrastructure and critical areas would be 7.55-acres. If 30 units were proposed on the property, the net density would be 4-units per net acre (30-units/7.55-acres = 4 units/acre). Applicants are required to display this information on the face of the plat in a table format like shown below. See the Plat, Table, and net density calculation examples below.

2 Density calculations are jurisdiction-specific: from a purely scientific or engineering perspective, nearly

all of Ferndale’s future growth for the next decade or more could be contained in one large skyscraper.

However, the market conditions and financing of individual applicants in Ferndale is not the same as

Vancouver or Seattle – or Bellingham, for that matter. Thus Ferndale’s policy for density calculations is

significantly less than what might be expected in a larger city, but also more intense than what existed ten

or twenty years ago.

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Diagram 1. Local Plat Example with Roads and a Reserve Tract

Table 1. Local Plat Example Density Table for Plat in Diagram 1.

DENSITY TABLE

Acres Percentage %

Overall Parcel Area 3.99 AC 173, 945 SF 100

Private & Public Roads 0.73 AC 31,796 SF 18.28

Total Lot Area 2.84 AC 123,751 SF 71.14

Reserve Tract 0.42 AC 18,398 SF 10.57

For this plat, the net density would be calculated by dividing the number of units by the total lot area (18 units/2.84 acres = 6.33 units/net acre). The plat is located in the RS Medium Single-Family Zone which requires a density of 4-7 units per net acre. This plat falls within the required density range. Density Summary: In general, gross density is helpful to understand the overall densities of an area – a macro calculation. Net density acknowledges site-specific characteristics that may make individual developments more or less efficient and eliminates those inefficiencies from the calculation in order to arrive at a uniform starting point for measurement. However, it should be noted that there can be broad differences in the placement of “required infrastructure,” and the choices made to accommodate that infrastructure. As an example, most wetlands can be mitigated, road placement can often be reconfigured, the size and type of stormwater facilities can be altered, and more – generally at a cost to the applicant. This means that while net density seeks to let the land “speak” for itself, there are several ways to interpret what the land is saying.

Legend

Public & Private Roads

Total Lot Area

Reserve Tract

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Minimum Lot Size The City of Ferndale historically calculated single-family residential densities using a “Minimum Lot Size” calculation. For example, one of the previous Single-Family Zones in Ferndale (the RS 6.5 Zone) required a minimum lot size of 6,500 square feet. The Douglas Place Long Plat Div. 3 (Exhibit 3) shows an example of this requirement. The 16-lot plat yields a gross density of 5-units/acre based on the overall parcel area and a net density of 6-units/acre based on the overall parcel area deducting the right of way dedication. The City does not base density on minimum lot sizes alone any longer. The single-family and some multifamily zones do establish a very small minimum lot size requirement however, a density range (using net or gross) is also established to regulate the density. The use of a minimum lot size requirement as a basic metric for subdivision dates to the post WW2 era as suburban development became increasingly popular. The minimum lot size requirement (as well as substantial front setbacks) was intended primarily to ensure that this model for suburban development – expansive lots with large lawns – was achieved. Long-range plans from the era, where they existed, anticipated continued expansion of the city limits and water service area in order to accomplish this low-density growth. Density and Minimum Lot Size Calculations in Ferndale In general, a “Net Density” calculation is used in the Residential Single-Family zones and “Gross Density” is used in the Multifamily, City Center and Urban Residential Zones. In each zone a minimum density, maximum density, or a minimum and maximum density (range) is established. The Residential Office (RO) Zone3 calculates density based on the lots size with a maximum gross density established. The Mixed-Use Commercial Zone does not establish a minimum or maximum density for residential units. The City’s Commercial Zones (General Business, Regional Retail, Manufacturing and Light Industrial) do not establish a minimum or maximum amount of commercial uses required. The zones also do not establish ratios of land area to the area of buildings and structures. The size of the commercial uses is generally determined by the existing lot size, setbacks, lot coverage requirements, infrastructure requirements, parking and building heights. The Mixed-Use Commercial zone does establish a minimum component of non-residential uses required for the gross property size, not the net developable area. The table below displays the residential density and commercial requirements established for each zone (Exhibit 1 – Zoning Map).

3 The Residential Office (RO) Zone exists in three areas within the City. This zone was established in the

1970’s and is outdated. Staff intended to replace the RO zone with a new zone or existing zones in 2021.

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Underlying Zone

Density Calculation

Minimum Density (Dwelling Units)

Maximum Density (Dwelling Units)

Minimum Lot Size

RS Low Single- Family Dwelling

Per Net Acre 3 7 3,500 SF

RS Medium Single-Family Dwelling

Per Net Acre 4 7 3,500 SF

RS High Single-Family Dwelling

Per Net Acre 6 9 3,500 SF

RMM – Residential Multifamily Medium

Per Gross Acre

10 30 3,500 SF for detached single-family uses.

RMH – Residential Multifamily High

Per Gross Acre

15 No maximum.

3,500 SF for detached single-family uses.

RO – Residential Office Per Gross Acre

See FMC 18.40.050.

27 4,000 SF for first unit, 1,500 SF for each additional unit.

UR – Urban Residential Per Gross Acre

15 No Maximum

N/A

MXD – Mixed Use Commercial District

Per Gross Acre

No Minimum.

No Maximum.

None. Commercial minimums are based on a sliding scale in relation to property size.

CC – City Center Per Gross Acre

15 No Maximum.

N/A

RR – Regional Retail N/A N/A N/A None.

GB – General Business Zone

N/A N/A N/A None.

M – Manufacturing Zone N/A N/A N/A None.

LI – Light Industrial Zone N/A N/A N/A None.

PI – Public Institutional Zone

N/A N/A N/A None.

ANALYSIS: The net density calculation range within the single-family zones is meant to prevent applicants from placing “too few” or “too many” lots on a single parcel, and also enables the City to reliably plan ahead for future infrastructure needs. For example, the minimum density established in single-family zones prevents an applicant from purchasing a large property and building one or two mansions on

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the property. This results in a lower density within City limits and prevents additional infill. Further, the low-density example provided above would have the potential to significantly modify long-range infrastructure planning: if the City, Fire District, and School District had invested in infrastructure to support significant growth in that area and if that growth did not occur, the infrastructure would be under-utilized and the investment could be partially wasted. By establishing a range of densities, the City and other public agencies are able to reliably plan for growth. Conversely, the maximum density requirement in single-family zones prevents an applicant from creating a development (using the minimum lot size of 3,500 SF) that exceeds the Comprehensive Plan figures. For example, the City’s minimum lot size in residential zones is 3,500 SF4. On a 35,000 SF parcel, the applicant may wish to establish 10 lots using the minimum lot size area. The code also requires a density range of 4-7 units per acre which means the 35,000 SF parcel could only yield 5 lots. The minimum lot size and density range is meant to be used together for each development to allow for various lot sizes within the acceptable density range. From Staff’s perspective, applicants generally appreciate the flexibility built into the net density range calculation for single-family zones. Recently, staff has received feedback from applicants stating the minimum density limit is too restrictive for homeowners who wish to build on large parcels. Applicants have also asserted the net density calculation is unfairly restrictive for parcels with vast wetland areas or undevelopable portions of the property. For example, if a ten-acre property has nine acres of wetlands the applicant is left with less than an acre to apply the density calculation to. If the density was calculated as “gross” the applicant would in theory be able to maximum the density on the parcel while complying with the minimum lot size and other infrastructure requirements. Staff intends to analyze these issues more closely at a future date. The Residential Multifamily High (RMH) zone requires a minimum density of 15 dwelling units per acre. For example, there are a number of properties along Cedar Street that contain steep slopes that make portions of the property undevelopable. Recently, applicants have had a difficult time meeting the minimum density requirements because of this.5 Staff plans to incorporate greater flexibility with the minimum density requirement in the RMH Zone and will bring this issue to the Planning Commission in September.

4 This is the minimum lot size required for single family detached residences in order to preserve a

minimum building envelope of 40’ x 40’. 5 However, Staff also notes that while in some cases site conditions may prevent additional density, in other

situations the type of development proposed by an applicant, in combination with site-specific constraints,

may not result in the densities anticipated by the City. For example, the consolidation of multifamily units

into a smaller number of taller structures will necessarily open up more area for environmental protection

and infrastructure – but the cost of building a taller structure (three stories or taller requires an elevator and

a different method of construction) may prevent an applicant from seeking these more land-efficient

development approaches.

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CONCLUSION: Staff has provided a brief introduction to explain how densities are determined and calculated in Ferndale. Staff intends to present this matter to the Planning and Land Use Committee on September 2. Staff may also present this to the full Council if directed to by the Planning and Land Use Committee. Staff intends to have a discussion and answer any questions the City Council may have on this topic.

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Official Zoning 0 1,250 2,500 3,750 5,000625Feet

N o o k s a c k

R i ver

DISCLAIMER: USE OF THIS MAP IMPLIES THE USER'S AGREEMENT WITH THE FOLLOWING STATEMENT: The City of Ferndale disclaims any warranty of merchantability or warranty of fitness of this map for any particular purpose, either express or implied. No representation or warranty is made concerning the accuracy, currency, completeness or quality of data depicted on this map. Any user of this map assumes all responsibility for use thereof, and further agrees to hold the City of Ferndale harmless from and against any damage, loss, or liability arising from any use of this map.

City of Ferndale, WAO

City LimitsTax ParcelCC-City CenterRS Low-Single Family DwellingRS Medium-Single Family DwellingRS High-Single Family DwellingRMM- Residential Multifamily MediumRMH-Residential Multifamily High

RO-Residential OfficePI-Public/InstitutionalUR-Urban ResidentialRR-Regional RetailGB-General BusinessMC-Mixed Use Commercial DistrictLI-Light IndustrialM-Manufacturing

Map Content Date: October 2019

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Document Path: C:\DATA\Projects\ARCGIS PROJECTS\2019\PROPOSED_OfficialZoning_1117.mxd

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