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Glossary of Code Terms

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This glossary contains definitions specific to the Uniform Building Code unless another model code is referenced. The reader is cautioned against the transference or applicability of the definitions contained herein to other divisions within Permit Sonoma. For questions regarding applicable regulations, specifically as it relates to planning issues, consult the Sonoma County Zoning Ordinance and/or Permit Sonoma planning staff.

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Addition – extension or increase in floor area or height of a building or structure.

ADU – Accessory Dwelling Units (ADUs) are backyard cottages of between 250 and 1,200 square feet. More Information on ADUs

Agricultural building – structure designed and constructed to house farm implements, hay, grain, poultry, livestock and other horticultural products. This structure shall not be a place of human habitation or a place of employment where agricultural products are processed, treated or packaged, nor shall it be a place used by the public.

Air test – a test that is applied to a plumbing system upon its completion.

Alter or Alteration – is any change, addition, or modification in construction occupancy.

Approved – as to materials and types of construction, refers to approval by the building official as a result of investigation and tests conducted by the building official, or by reason of accepted principals or tests by recognized authorities, technical or scientific organizations.

Approved agency – an established and recognized agency regularly engaged in conducting tests or furnishing inspection services, when such agency have been approved.

Approved fabricator – an established and qualified person, firm or corporation approved by the building official pursuant to Section 1701.7 of this code.

Basement – any floor level below the first story in a building, except that a floor level in a building having only one floor level shall be classified as a basement unless such floor level qualifies as a first story as defined herein.

Bathroom – an area including a basin and one or more of the following: a toilet; a tub; or a shower as defined in the 2001 California Electrical Code.

Blocked Diaphragm – a diaphragm in which all sheathing edges not occurring on framing members are supported on and connected to blocking.

Boiler – a closed vessel used for heating water or liquid, or for generating steam or vapor by direct application of heat from combustible fuels or electricity

Braced wall panel – is a section of wall braced in accordance with Section 2320.11.3 Bracing Provisions.

Building – any structure to which state agencies have regulatory power used or intended for supporting or sheltering any use or occupancy, housing or enclosure of persons, animals, chattels, equipment or property of any kind and also includes structures wherein things may be grown, made, produced, kept, handled, stored or disposed of and all appendages, accessories apparatus, appliances and equipment installed as a part thereof.

'Building' shall not include machinery, equipment or appliances installed for manufacture or process purposes only, nor shall it include any construction installations which are not a part of a building, any tunnel, mine shaft, highway or bridge, or include any house trailer or vehicle which conforms to the Vehicle Code.

Building, existing – a building erected prior to the adoption of this code, or one for which a legal building permit has been issued.

Building official – The officer or other designated authority charged with the administration and enforcement of this code, or the building official's duly authorized representative in accordance with state law. Health and Safety Code Section 13146, in occupancies regulated by the State Fire Marshal.

Building or structure – shall include structures such as porches and steps, whether covered or uncovered, breezeways, roofed Porte-coheres, roofed patios, carports, covered walks, covered driveways and similar structures or appurtenances. As defined in the 2001 California Plumbing Code.

Conditioned Space – in residential compliance, conditioned space is space in a building that is either directly or indirectly conditioned.

Conditioned Space, indirectly - indirectly conditioned space is enclosed space including, but not limited to, unconditioned volume in atria, that (1) is not directly conditioned space; and (2) either (a) has an area-weighted heat transfer coefficient to directly conditioned space exceeding that to the outdoors or to unconditioned space, or (b) is a space through which air from directly conditioned spaces is transferred at a rate exceeding 3 air changes per hour.

Indirectly conditioned space must be included when calculating total conditioned floor area. Examples of areas that may be indirectly conditioned space include enclosed porches, enclosed sunrooms, laundry rooms and furnace closets.

Conventional light-frame construction – a type of construction whose primary structural elements are formed by a system of repetitive wood framing members. Refer to Section 2320 for conventional light-frame construction provisions.

Cord-and-plug connected lighting assembly – a lighting assembly consisting of a lighting fixture intended for installation in the wall of a storable pool, and a cord-and-plug connected transformer.

Corrosion Resistant – a nonferrous metal or any metal having an unbroken surface of nonferrous metal or steel with not less than 10 percent chromium or with not less than 0.20 percent copper.

Diaphragm – a horizontal or nearly horizontal system acting to transmit lateral forces to the vertical-resisting elements. When the term "diaphragm" is used it includes horizontal bracing systems.

Dwelling – any building or portion thereof that contains not more than two dwelling units.

  • Dwelling: (NOTE: Definition per 2001 California Electrical Code)
  • Dwelling unit: One or more rooms for the use of one or more persons as a housekeeping unit with space for eating, living, and sleeping, and permanent provisions for cooking and sanitation.
  • One-Family Dwelling: A building consisting solely of one dwelling unit.
  • Two-Family Dwelling: A building consisting solely of two dwelling units.
  • Multi-Family Dwelling: A building containing three or more dwelling units.

Dwelling unit – any building or portion thereof that contains living facilities, including provisions for sleeping, eating, cooking and sanitation, as required by this code, for not more than one family, or a congregate residence for 10 or less persons.

Efficiency dwelling unit - a dwelling unit containing only on habitable room.

Exit – See " Means of egress."

Exterior wall – any wall or element of a wall, or any member or group of members, which defines the exterior boundaries or courts of a building an which has a slope of 60 degrees or greater with the horizontal plane (Section 224).

Fire resistance or fire resistive construction – is construction to resist the spread of fire, details of which are specified in this code.

First Floor of a Building - For the purpose of this section of the Code the First Floor of a Building shall be that floor that has fifty percent (50%) or more of the exterior wall surface area level with or above finished grade. One additional level that is the first level and not designed for human habitation and used only for vehicle parking, storage or similar use is permitted (NOTE: This is from the 2001 California Plumbing Code)

Footing – portion of the foundation of a structure that spreads and transmits loads directly to the soil or the piles.

Garage – a building or portion thereof in which a motor vehicle containing flammable or combustible liquids or gas in its tank or an electric vehicle with a rechargeable storage battery, fuel cell, photovoltaic array or other source of electric current is stored, repaired, charged (electric vehicles only) or kept.

Garage, Private – is a building or a portion of a building, not more than 1,000 square feet (93 m²) in area, in which only motor vehicles used by the tenants of the building or buildings on the premises are stored or kept.

Garage, Public – is a garage other than a private garage.

Gas Log – a self-contained, free-standing, open-flame, gas-burning appliance consisting of a metal flame or base supporting simulated logs, and designed for installation only in a vented fireplace.

Geotechnical Report – Geotechnical reports provide information on the physical properties of soil and rock around a site. The reports are used to communicate the site conditions and design and construction recommendations to the site design, build design, and construction personnel. The investigations required for geotechnical reports are performed by geotechnical engineers or engineering geologists.

Grade (adjacent ground elevation) – the lowest point of elevation of the finished surface of the ground paving or sidewalk, within the area between the building and the property line or, when the property line is more than 5 feet (1524 mm) from the building, between the building and a line 5 feet (1524 mm) from the building.

Greenhouse – (See " Agricultural Building") Structure designed and constructed to house horticultural products. This structure shall not be a place of human habitation.

Grounded – Connected to the earth or to some conducting body that serves in place of earth.

Grounded Conductor – A system or circuit conductor that is intentionally grounded.

Grounding Conductor – A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode.

Grounding Conductor, Equipment – The conductor used to connect the non-current carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both at the service equipment or at the source of a separately derived system.

Grounding Electrode Conductor - The conductor used to connect the grounding electrode to the equipment grounding conductor, to the grounded conductor, or to both, of the circuit at the service equipment or at the source of a separately derived system.

Guardrail – a system of building components located near the open sides of elevated walking surfaces for the purpose of minimizing the possibility of accidental fall from the walking surface to the lower level or a vertical barrier erected along the open edges of a floor opening, wall opening, ramp, platform, runways or other elevated area to prevent persons from falling off the open edge.

Habitable space (room) – a space in a structure for living, sleeping, eating or cooking. Bathrooms, toilet compartments, closets, halls, storage or utility space, and similar areas are not considered habitable space.

Handrail – a railing provided for grasping with the hand for support. See also " Guardrail."

JADU – Junior Accessory Dwelling Units (JADUs) are a very small living unit (up to 500 square feet) created out of a bedroom within an existing single family home. More Information on JADUs

Industrial Waste – Any and all liquid or waterborne waste from industrial or commercial processes, except domestic sewage.

Listed and listing – terms referring to equipment or materials included in a lists published by an approved testing laboratory, inspection agency, or other organization concerned with product evaluation that maintains periodic inspection of current productions of listed equipment or materials. The published list shall state that the material or equipment complies with approval nationally recognized codes, standards or tests and has been tested or evaluated and found suitable for use in a specified manner.

Means of egress – an exit system that provides a continuous, unobstructed and undiminished path of exit travel from any occupied point in a building or structure to a public way.

Noncombustible – as applied to building construction material means a material that, in the form, in which is used, is either on of the following:

  1. Material of which no part will ignite and burn when subjected to fire. Any material conforming to UBC. Standard 2-1 shall be considered noncombustible within the meaning of the section.
  2. Material having a structural base of noncombustible material as defined in Item 1, with a surfacing material not over 1/8 inch (3.2 mm) thick which has a flame-spread rating of 50 or less.

Non-Standard Septic Systems – The County's Operational Permit Program for permitting Non-Standard Septic Systems or approved pretreatment units.

Occupancy – the purpose for that a building or part thereof, is used or intended to be used.

Occupancy separation – a fire resistive separation between each occupancy either vertical or horizontal or both or when necessary of such other form as may be required to afford a complete separation between the various occupancy divisions in the building. Where the occupancy separation is horizontal structural members supporting the separation shall be protected by equivalent fire-resistive construction.

Open circuit condition – refers to no continuity between circuit conductors.

Panel board – a panel or group of panels assembly consisting of bus bars, automatic overcurrent protection devices, etc designed to be placed in a cabinet or cutout box placed in or against a wall or partition and accessible only from the front.

Patio Cover – One-story structure not exceeding 12 feet in height. Enclosure walls may have any configuration, provided the open area of the longer wall and one additional wall is equal to at least 65% of the area below 6 feet, 8 inches of each wall, a measured from the floor. Openings may be enclosed with insect screening or plastic that is readily removable. Translucent or transparent plastic not more than 0.125 inch in thickness. They shall be used only for recreational, outdoor living purposes and not as carports, garages, storage rooms or habitable rooms.

Pressure gauge – an instrument for measuring the pressure of fluids, gases or air.

Pressure relief valve – a pressure-activated valve held closed by a spring or other means and designed to automatically relieve pressure in excess of setting; also called safety valve.

Private Riding Arena – means an enclosed or unenclosed building or a portion of a building used exclusively for private equestrian activities by the building owners, guests or employees not to exceed a capacity of thirty (30) persons. The area within the private riding arena shall not be used for storage areas, animal stalls, offices, viewing areas, shows, events, public riding lessons or similar uses or occupancies. Such buildings shall be classified as Group U, Div. 3 occupancy.

Private swimming pool – any structure, whether in-ground or above ground, designed or used for swimming or recreational bathing that contains water in excess of 18 inches.

PSI – Pound pressure per square inch.

Remodeling – See "Alter or Alteration."

Repair – the reconstruction or renewal of any part of an existing building for the purpose of its maintenance.

Smoke Detector – a state fire marshal approved and listed device that senses visible or invisible particles of combustion.

Storable swimming or wading pool – Those that are constructed on or above ground and are capable of holding water to a maximum depth of 42 inches or a pool with nonmetallic molded polymeric walls or inflatable fabric walls regardless of dimension.

Story – That portion of a building included between the upper surface of any floor and the upper surface of the floor next above, except that the topmost story shall be that portion of a building included between the upper surface of the topmost floor and the ceiling or roof above. If the finish floor level directly above a useable or unused under-floor space is more than 6 ft (1829 mm) above grade, as defined herein, for more than 50 percent of the total perimeter or is more than 12 feet (3658 mm) above grade, as defined herein, at any point, such usable or unused under-floor space shall be considered a story.

Story, first – the lowest story in a building that qualifies as a story, as defined herein, except that a floor level in a building having only one floor level shall be classified as a first story, provided such floor level is not more than 4 feet (1219 mm) below grade, as defined herein, for more than 50 percent of the total perimeter or not more than 8 feet (2438 mm) below grade, as defined herein, at any point.

Structural observation – the visual observation of the structural system, for general conformance to the approved plans and specification, at significant construction stages and at completion of the structural system. Structural observation does not include or waive the responsibility of the inspection required by Section 108, 1701 or other sections of this code.

Structure – that which is build or constructed, as edifice or building of any kind, or any piece of work artificially built up or composed of parts joined together in some definite manner.

Technically infeasible – With respect to an alteration of a building or a facility, that is has little likelihood of being accomplished because existing structural conditions would require removing or altering a load-bearing member which is an essential part of the structural frame; or because other existing physical or site constraints prohibit modification or addition of elements, spaces or features which are in full or strict compliance with the minimum requirements for new construction and which are necessary to provide accessibility.

Temporary Occupancy Permit: A permit that allows individuals to occupy a building or a portion of a building before the building is completed. More information

Through-penetration fire stop – is a material, device or construction installed to resist, for a prescribed time period, the passage of flame, heat and hot gases through openings which penetrate the entire fire-resistive assembly in order to accommodate cables, cable trays, conduit, tubing, pipes or similar items.

Total perimeter – the outer limits of the lowest level under consideration. The perimeter is the bound area formed by the exterior walls of that level. Posts which support an upper structure are considered an exterior wall. Cantilevered exterior balconies or decks are not included (Section 224 and Reference 2.).

Treated wood – wood treated with an approved preservative under treating and quality procedures.

Unconditioned Space – A space that is neither directly or indirectly conditioned space, which can be isolated from conditioned space by portions and/or closable doors.

Unreasonable Hardship – exists when the enforcing agency finds that compliance with the building standard would make the specific work of the project affected by the building standard unfeasible, based on an overall evaluation of the following factors:

  1. The cost of providing access.
  2. The cost of all construction contemplated.
  3. The impact of proposed improvements on financial feasibility.
  4. The nature of accessibility which would be gained or lost.
  5. The nature of the use of the facility under construction and its availability to persons of disabilities. The details of any finding of unreasonable hardship shall be recorded and entered in the files of the enforcing agency.


  • Bearing wall – any wall meeting either of the following classification:
    1. Any metal or wood study wall that supports more than 100 pounds per linear foot (1.459 kN per linear meter) of superimposed load.
    2. Any masonry or concrete wall that supports more than 200 pounds per linear foot (2.918 kN per linear meter) superimposed load, or any such wall supporting its own weight for more than one story.
  • Exterior wall – any wall or element of a wall, or any member or group of members, that defines the exterior boundaries or courts of a building and that has a slope of 60 degrees or greater which the horizontal plane.
  • Faced wall – a wall in which the masonry facing and backing are so bonded as to exert a common action under load.
  • Nonbearing wall – any wall that is not a bearing wall.
  • Parapet wall – is that part of any wall entirely above the roof line.
  • Retaining wall – is a wall designed to resist the lateral displacement of soil or other materials.

Water heater – an appliance designed to supply hot water and is equipped with automatic controls limited water temperature to a maximum of 210° F (99° C).

Wind Speed

  • Basic – is the fastest-mile wind speed associated with an annual probability of 0.02 measured at a point 33 feet above the ground for an area having Exposure C category.
  • Exposure B – has terrain with buildings, forest or surface irregularities, covering at least 20% of the ground level area extending one mile or more from the site.
  • Exposure C – has terrain that is flat and generally open extending 1/2 mile or more from the site in any full quadrant.
  • Exposure D – represents the most severe exposure in areas with Basic Wind Speeds of 80 miles per hour or greater and has terrain that is flat and unobstructed facing large bodies of water over one mile or more in width relative to any quadrant of the building site. Exposure D extends inland from the shoreline 1/4 mile.

Wood of natural resistance to decay or termites – the heartwood of the species set forth below. Corner sapwood is permitted on 5 percent of the pieces provided 90 or more of the width of each side on which it occurs is heartwood. Recognized species are:

  • Decay resistant: Redwood, Cedars, Black Locust.
  • Termite resistant: Redwood Eastern Red Cedar.