But with a finite amount of land to house us, communities all around the globe have come to understand the need and benefits of density (saving land and energy use, for starters).  Here in Washington State, the Growth Management Act dictates that cities plan for anticipated growth, which, in many cases, means more density in areas with the infrastructure to support it.

Zoning codes all regulate density in some form. Single family districts include lot size minimums. Multifamily districts often include a maximum number of dwelling units allowed per acre. Major political battles often erupt when density increases are proposed. Community members may fight against a proposed density number, but often they don’t know what it looks like.

Over the past few years, I’ve conducted a slideshow and discussion on density to planning commissions and committees in multiple cities. The major conclusion of the analysis is that perceptions on density depend on design. As author Julie Campoli noted in her 2007 book, Visualizing Density, people tend to overestimate the density of monotonous, amenity-poor developments and underestimate the density of well-designed, attractive projects, thereby reinforcing negative stereotypes.

This article shows examples of various densities in Washington State communities and closes with a summary of design elements that help to make density more compatible.

Clarification of Gross Versus Net Density

First, it’s important to clarify how densities are measured. Zoning codes either measure density on a gross or net basis. Net density includes just individual lots in the measurements while gross density includes street rights-of-way and common areas. As a consequence, net density figures are typically 50-70% higher than gross density numbers.

Gross density measurements are often best used when looking at large developments that are likely to have internal roads and open space. Net densities are often more appropriate for neighborhood infill situations. The graphics below, courtesy of GGLO, help to explain the differences.

Density Examples

4 Dwelling Units Per Acre (Gross)

Notable features: The lack of street trees combined with a prevalence of garages and driveways. The city’s new standards, however, reduce street widths, include wide planter strips and street trees, and deemphasize the garage in the design of home fronts.

Newer, single-family subdivision in Ellensburg

5.3 Dwelling Units Per Acre (Gross)

Notable features: Traditional streetscapes with sidewalks, planter strips, street trees, covered entries, and a diversity of architectural styles. Access to garages is provided by an alley behind the single-family houses.

Older, single-family neighborhood in Olympia, WA.

5.9 Dwelling Units Per Acre (Gross)

Notable features: Traditional streetscape with sidewalk, street trees, shallow front setbacks and front porches. The courtyard-access lots behind the street-fronting homes add density, but its density that’s largely screened from the street. Note that the second row of homes at the top and bottom of the image are accessed by private lanes.

Relatively new, single-family subdivision within the master-planned Snoqualmie Ridge development (Snoqualmie, WA)

7.7 Dwelling Units Per Acre (Gross)

Notable features: Consistent setbacks, shallow porches, minimal setbacks between homes, and alleys with driveway space in back. The monotonous layout and design, combined with the lack of usable open space for residents, led to updates to Lacey’s zoning and design standards.

Relatively new, small-lot homes in the Hawks Prairie development (Lacey, WA).

9.3 Dwelling Units Per Acre (Gross)

Notable features: Traditional streetscapes, a combination of front- and alley-loaded dwellings, and strategically located, common open space. The numbers below refer to duplexes (2) and triplexes (3).  The remaining structures are single-family homes.

Relatively new, mixed-housing-type subdivision within the master-planned Issaquah Highlands development (Issaquah, WA).

15 Dwelling Units Per Acre (Gross)

Notable features: A variety of housing types, pedestrian-friendly street frontages, alleys and auto courts, and common open space with trails.

Relatively new, mixed-housing-type subdivision, also within the master-planned Issaquah Highlands development (Issaquah, WA).

18 Dwelling Units Per Acre (Net)

Notable features: A combination of surface/garage parking and generous open space and recreational features (including children’s play area, sports court, vegetable gardens for residents, trails, common recreational building, and a protected natural area).

New apartment community in Renton, WA

27 Dwelling Units Per Acre (Net)

Notable features: Single and double-single family lots redeveloped with condominiums.  Each building contains between 3-7 units and has front-loaded parking at the street level beneath the dwelling units. All are built within a strict 30’ height limit; hence, the flat roofs.

5th Avenue condominiums in Kirkland, WA

34 Dwelling Units Per Acre (Net)

Notable features: An urban, street-oriented townhouse development integrating corner retail spaces, live-work spaces, internal auto courts with private garages, and common open space.

Lionsgate Townhouses in Redmond, WA

36 Dwelling Units Per Acre (Net)

Notable features: A cluster of single-family homes integrated into surrounding neighborhood with alley and internal auto-court access, private garages, a large cedar tree, and a manmade stream running through the site.

Detached, single-family homes in The Boulders at Green Lake development in Seattle, WA (images courtesy of Johnston Architects).

44 Dwelling Units Per Acre (Net)

Notable features: New urban townhouses and live-work units served by underground parking and containing private patios and a centralized, shared courtyard space.

Live-work and regular townhouse units in Seattle’s Lower Queen Anne neighborhood (landscape plan courtesy of David Vandervort Architects).

59 Dwelling Units Per Acre (Net)

Notable features: The whole block site transitions from 4-story buildings with ground level retail to townhomes that rise only one level above the street at the northwest corner of the site. While the L-shaped, mixed-use apartment building is over 100 dwelling units per net acre, the surface parking area and townhouse building bring the block’s average density down to 59 units per net acre.

Nia Apartments and townhouses in White Center (King County, WA).

162 Dwelling Units Per Acre (Net)

Notable features: A 6-story, mixed-use apartment building in the very urban, First Hill neighborhood.

Apartments over ground level retail in Seattle’s First Hill neighborhood (left image courtesy of GGLO).

205 Dwelling Units Per Acre (Net)

Notable features: This mixed-use project now under construction features 41 studio apartments averaging only 430 square feet. The trend in smaller units in urban areas results in a much higher density count than would be assumed in looking at this 4-story building. It replaces two single-family homes and features only eight parking spaces but will be within walking distance of a future light rail station.

Studio apartments over ground level retail in Seattle’s Roosevelt neighborhood (images courtesy of Weinstein A+U).

Conclusions: What Makes Density Compatible?

Some quick observations about the examples above and key elements that make them appear more or less livable or attractive.

Good streetscape. Since the most common perception of cities is from our view at street level, the quality of the streetscape in front of the buildings makes perhaps the biggest impact in humanizing developments and softening the hard edges of buildings. Street trees are present in all of the examples above, except the very first example in Ellensburg, and it’s notable that new streetscape standards for Ellensburg now require planting strips with trees! The mixed-use building photos above were all taken during the wintertime. Summertime photos from the same vantage point would certainly soften the edges of those buildings!

Vehicular access elements. Streetscapes dominated by views of garages tend to create more of a dehumanized setting. While they may not necessarily make a streetscape feel more dense, the garages certainly degrade the visual character. The Issaquah Highlands examples above are particularly successful in locating and designing garages and driveways in a manner that minimizes their visual impact on the streetscape.

Attractive streetscapes go a long way towards making higher-density neighborhoods livable. Poor streetscapes that are auto-dominated and lack softening greenery can make an area feel more crowded.

Building design. There are a number of building features that can impact a person’s perception of the building.

• Façade massing. Large buildings featuring good articulation techniques that break down the perceived scale of the building and add visual interest will appear less dense than a boxy and poorly detailed building.
• Façade materials & detailing. Buildings with materials and detailing that add visual depth and interest to a view will also be perceived as less dense and more livable.
• Variety. While some consistency in built form can be good and help to establish a sense of place, monotonous designs (particularly those with poor streetscapes, façade massing, materials, and detailing) can degrade the visual character and make the area feel denser than it is.

The top images feature good façade articulation and detailing that add visual interest and reduce the perceived scale of the buildings.  The image below features monotonous setbacks and building forms.  While some variety of color and porch roof forms are included, it still comes across as excessively monotonous.

Credits

The following planners provided assistance in this piece: Steve Butler and Byron Katsuyama (MRSC), Jeremy McMahan (Development Services Planning Manager, City of Kirkland), Chip Vincent and Clark Close (Long Range Planning Director/ Senior Planner, City of Renton), Gary Lee (Senior Planner, City of Redmond), Lisa Rutzick (Design Review Program Manager, City of Seattle), Joming Lau (Urban Design, MAKERS) and Sean McCormick (Urban Designer, MAKERS).