Single Story Overlays


What is a Single Story Overlay (SSO)? 

A single story overlay is a zoning regulation which requires all homes in a designated area to have just one habitable floor. Homes within a single story overlay may not exceed 17 feet in height as measured from the peak of the roof. In a special flood hazard area, this height may be increased as high as 20 feet. 

Palo Alto Municipal Code Sections on Single Story Overlays

Palo Alto Municipal Code (PAMC) Section 18.12.100 describes single story overlay applicability and site development regulations. Palo Alto Municipal Code (PAMC) Section 18.80.035 describes the rezoning process. Please view these sections within the Palo Alto Municipal Code (PAMC) to learn more.

SSO Zoning Change Application and Approval Process

Any property owner(s) within a neighborhood may submit an application for a Single Story Overlay (SSO) Rezoning. The above referenced municipal code section requires evidence that 70% of property owners in the area of interest support rezoning at the time of the application's submission. In the case of a neighborhood with covenants codes and restrictions that limit development to single story homes, the code only requires evidence of support from 60% of property owners.

When the City receives an application that includes evidence of the required levels of support, City staff forwards the proposal to the Planning and Transportation Commission (PTC).  Staff shares the current level of support at the public PTC hearing, based upon any additional evidence received from any new owners submitting signatures in support and any persons requesting to withdraw their earlier signature of support. (It is important to note that the City staff does not gather “votes” of property owners at any point in this process.) Following the public hearing conducted by the Planning and Transportation Commission, the City Council acts as the final decision-maker on any SSO zoning changes.

Non-Complying Homes in a SSO Zone

An existing two-story home or home exceeding a height of 17 feet above grade (or 20 feet above grade in flood zones) becomes a ‘non-complying facility’ following SSO adoption. Additionally, some existing homes may encroach into a required side or rear yard setback, or exceed allowable maximums for lot coverage or floor area.  Such homes are also considered ‘non-complying facilities.

Restrictions as to what may be done to such non-complying facilities are set forth in Palo Alto Municipal Code (PAMC) Chapter 18.70 sections 18.70.080, 18.70.090 and 18.70.100. Home improvement exceptions (HIEs) are an option to modify such homes when 75% of the exterior walls remain in place as exterior walls.  The HIE process, eligibility and findings are contained in Palo Alto Municipal Code (PAMC) Chapter 18.12, Section 18.12.120.  However, if improvements result in more than 25% of the exterior walls being removed, the project is no eligible for HIE.

Below is a brief summary of the rules governing alterations to such non-complying facilities.

  • A two story home destroyed by non-willful means (referred to as “act of God”) may be rebuilt in the same two-story footprint, envelope, etc. per Palo Alto Municipal Code Chapter 18.70.
  • Intentional removal of an existing, non-complying, two-story home in a SSO zone district would result in the requirement to construct a compliant, one-story home limited to 20 feet in height on the property.
  • Maintenance, repair or limited enlargement that does not increase the “degree of non-compliance” of a non-complying facility can be permitted. Palo Alto Municipal Code (PAMC) Section 18.70.080 allows for limited enlargement of a non-complying facility within a SSO, but a homeowner cannot add more floor area on the second floor, for instance.  Enlargement or improvement of the first floor, as otherwise permitted by the Zoning Code, is allowable. Palo Alto Municipal Code (PAMC) Chapter 18.70 also refers to Section 18.12.050, permitted encroachments, projections and exceptions, which allows limited encroachments of first floor areas into required setbacks.
  • Home improvement exceptions (HIEs) are an option for additions to non-complying facilities when there are special circumstances, such as existing reduced setbacks.  An addition may be allowed to encroach into a setback or exceed allowable lot coverage or floor area if findings for HIE approval are made.

Recently Approved Single Story Overlays

The City recently approved two single-story overlays; one in 2015 and one in 2016. For more information, please view the SSOs adopted in 2015 and 2016 flyer or view the ordinances linked below.