Single Family FAQs

The lot area is the area of the parcel, and can be measured or verified by a surveyor. Some of this area may need to be excluded from the calculations, such as:

•     Street right-of-way
•     Natural waterway, river, creek or stream, or flood control or drainage easement
•     The portion of a flag lot connecting to the street

Lot coverage refers to the footprint of all structures, plus the roof eaves and patio/porch overhangs. Basically, if you took an aerial photo of your property and traced the outline of all structures, that is lot coverage. 

In R-1, 45% of the lot can be covered by structures, with an additional 5% allowed for coverage by roof overhangs, patios, porches, and other structures not enclosed by walls on at least three sides.

Floor area is the total area of all habitable floors of a building measured to the outside of exterior walls including the following:

•     Depth of all walls
•     Rooms
•     Hallways
•     Stairways
•     Base of stairwells
•     Base of elevator shafts
•     Services and mechanical equipment rooms
•     Interior building area above 15 feet in height between any floor level and the ceiling above
•     Residential garages
•     Roofed arcades, breezeways, porches, and similar features that are enclosed by walls on three sides
•     All accessory structures, such as sheds and Accessory Dwelling Units

The following features are not included in floor area calculations:

•     Basements with lightwells that conform to Section 19.28.070(I)
•     Lightwells
•     Attic areas

The Floor Area Ratio (F.A.R.) of a property/development is calculated by dividing the floor area of the development by the lot area. 

The Maximum FAR determines how many square feet can be built on a property. In R1 Zoning Districts, the Maximum FAR is 0.45 or 45%.

Example: Calculating F.A.R. for R1 Property

In this scenario, a maximum of 4,500 square feet can be built.

In R1 zoning districts, interior building area above 16 feet from the finished floor to the top of the rafters is counted twice toward Floor Area.

For instance, if a single story home has an 18 foot tall entry way, the area of the floor of the entry way and the area of the entry way at 16 foot height are both counted, as though there is a second story at 16 feet. This would all apply to the floor area of the home.

In a two story home, the first floor portion of the high volume area would apply toward the first floor Floor Area and the area where the second story would intersect would apply to the second floor Floor Area.

Common examples where Floor Area is counted twice include:

•     Entry ways
•     High Volume living rooms
•     Staircases
•     Garages

Floor area differs from Lot Coverage in that it only calculates floor area to the exterior of the wall, not overhangs, but also that it counts second story square footage. 

Therefore, the lot coverage of a two story home may be almost half the square footage of it's Floor area and the lot coverage of a single story home may be quite close to it's Floor area.

The building envelope is like an imaginary tent placed on your property within which single story elements of your home (including eaves) or single-story sections of two-story homes must fit. 

Exception: A gable end of a roof enclosing an attic space may encroach outside of the building envelope and have a maximum wall height of 17 feet from natural grade to the peak of the roof, or 20 feet with a Minor Residential Permit.

For most R1 zoned property, a 10’ tall vertical imaginary line is drawn at all the property lines that then has intersecting lines at a 25-degree angle that peak towards the center of the property.

In the R1-a zone, the imaginary vertical line is 12’ tall and located 10 feet inside the property lines.

The rear yard setback in R1, R2 and R3 zoning districts may be reduced so long as the amount of usable rear yard prescribed in the ordinance is provided.

In the R1 zoning district, the required 20 foot rear yard setback may be reduced to 10 feet with a Minor Residential Permit as long as the usable rear yard area is at least 20 times the lot width (measured from the front setback line).

Example: Determining Building Addition allowed