THINGS TO KNOW WHEN PLANNING
AN ADDITION TO AN EXISTING
SINGLE FAMILY HOUSE
The following is a list of unusual or special requirements for single family home additions or construction. In addition to these requirements, all homes are subject to development standards such as setbacks, lot coverage and height limitations. These residential development standards vary depending on the zoning district of the property. Please refer to the Setback and Zoning Requirements for R-0, R-1, and R-2 Zoning Districts (PDF) brochure (these zoning districts include most of the single family homes in Sunnyvale) for a graphic display of the development standards.
DESIGN REVIEW
All new second stories or any residential addition that is greater than 20% of the existing floor area (including the garage) is subject to Design Review, based on the Single Family Home Design Techniques. These techniques are policy statements on neighborhood compatibility, architectural detail and privacy. A copy of these techniques is available from the Planning Division. Important design considerations include:
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Compatibility with the neighborhood. The appearance of the house must be compatible with the established character of the neighborhood in terms of size, scale, mass and architectural features.
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Compatibility with the existing house. Additions should match the style of the existing residence and have the same or compatible exterior colors and materials.
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Window placement and design. New second story windows will be reviewed to minimize possible visual intrusion into adjacent properties. In some cases, frosted glass or privacy windows may be required.
All new second stories require noticing of adjacent neighbors. For additions or homes that are equal to or less than the Floor Area Ratio (FAR) threshold or square footage threshold for each zoning district, the application may be reviewed at the staff level. Projects that exceed the threshold FAR or square footage must be reviewed at a public hearing by the Planning Commission.
FIRE SPRINKLERS
Fire sprinklers are required for all new residential units in the City of Sunnyvale. Fire sprinklers are also required for additions where the additional square footage is greater than 50% of the existing living area (not including the garage). Fire sprinkler installation is not required for interior remodeling. A Fire Protection Engineer can answer any questions you have about this requirement.
ROOF MATERIALS
Roof materials must equal or improve the quality of the existing material on the house. For example, 30 year composition shingles must be replaced with 30 year or better. Any proposed change that would not equal the quality of the existing roof must be reviewed through a no-fee Miscellaneous Plan Permit. If the home is in a Planned Development, proposed roofing materials must follow the approved materials in the original Special Development Permit.
PARKING
If you would like to convert an existing garage or carport into living area, you will be required to provide an equivalent number of covered parking spaces on your property. A two-car garage has a required minimum area of 400 sq. ft. The interior dimension of the garage cannot be reduced to less than 17' (w) x 18' (d). Existing garages /carports which do not meet these minimum dimensions may not be reduced further in size.
Existing homes with sub-standard parking (less than two garage spaces and two driveway spaces) are required to upgrade the parking to meet the minimum standards whenever an addition is proposed that will result in either four or more bedrooms or total square footage of 1,800 square feet or more (including the garage).
SOLAR STUDY
For any new second story addition, a solar access study may be required showing projected shadow patterns on roofs of adjacent properties. No structure may shade more than 10% of the area of an adjacent property’s roof. Please speak with a planner for more details on solar access study requirements.
VISION TRIANGLES
Vision triangles are areas which must be kept clear of all objects except for fences, hedges shrubs or other natural objects of 3 feet or less in height. All lots must maintain a 10 foot driveway vision triangle, created by measuring ten feet along the outer edge of a driveway and ten feet along the back edge of a public sidewalk from the point where the driveway and sidewalk meet. Corner lots must maintain a corner vision triangle of 40 feet, formed by measuring 40 feet along each property line from the corner where the two street side of the property meet. Please see information on vision triangles for further details.
Questions?
Call or visit the One-Stop Permit Center at City Hall. Planners are available to assist you between the hours of 8 a.m. to 12 p.m. and 1 p.m. to 5 p.m.