Height Limits

Article

Height limits are one of many planning tools used to manage the density and character of development in urban areas. Buildings of similar height will typically have a more uniform appearance. Height homogeny can also help link buildings together. The range of human vision largely affects the perception of appropriate street space and scale. Height-to-width ratios can be used to describe the relationship between the relative amounts of visible street wall/buildings and sky.

In areas with very low height-to-width ratios, creating spatial definition can be quite difficult. Conversely, areas with height-to-width ratios at or above 3:2 can seem claustrophobic and overwhelming, and buildings may be difficult to read.

In light of the important role building height plays in shaping the streetscape, some communities choose to implement height limits. Height limits can be used to protect the architectural integrity and prominence of important buildings, mountain, waterfront, or other scenic vistas (e.g. citywide height limits implemented in San Francisco), or protect solar access to streets.

Boundaries between different height districts can be addressed in a number of ways, including building height contours, transitional height zones, point net envelope, and variable height extension.

Establish a building height minimum. Buildings with less than two-stories fail to create a sense of enclosure and space. Generally, wider streets require taller street walls, according to the ratios above. Real estate value plays a role in determining the market's desire to build up. In major downtown areas, height limits may be enforced for a number of reasons. For most other areas, where real estate values are not as high, and particularly along commercial/service corridors, building height minimums are important in creating a street-wall and welcoming pedestrian environment.

Recognize different needs for different uses. Some ordinances address maximum building height using "feet" and others use floors or stories. Specifying height limits in floors can allow retail spaces in commercial and mixed-use settings the higher ceilings desired on the ground floor (16' to 20'). Specifying a height limit in feet, for example 45', can unintentionally limit commercial buildings to three floors. Similarly, "loft" style housing is defined in part as having high ceilings, so mixed-use developments that are trying to create loft housing may conflict with height limits more often than traditional mid-century types of residential development.

Consider height requirements and/or limits in combination with density and solar access. While height limits are the most common tool for controlling building height, communities may also use solar access angles and density controls linked to lot size.

Allow for step-back. Some ordinances address overall height but also address the height of the street wall, allowing projects to step-back with subsequent stories so that the apparent scale is not as great, but the density can still be higher. Step-back design may also improve solar access.

Recognize the impact of height requirements and/or limits on building construction. Depending on local circumstances, such as building codes, fire codes, climate, seismic classification, and others, height requirements and/or limits can determine the type of construction that is possible. Generally, buildings taller than three floors must have elevators. Some cities require any commercial space above ground floor (including office) to be elevator served. Depending on local codes, the practical limit for wood frame buildings is somewhere around three to five floors. Anything above that may require steel or reinforced concrete framing. This can vary with zoning. Some ordinances address total height and others address height to the eave or drip line, allowing sloped roofs and dormers above. Ordinances should be explicit about accepted variations.

Also see the article on Urban Scale