Permit & ADU glossary

Plain-English definitions of the permit, ADU and California-housing terms that show up across Igni — each one links out to the long-form guides and articles.

Accessory Dwelling UnitAn accessory dwelling unit (ADU) is a smaller, self-contained second home on the same lot as a primary residence.Accessory StructureAn accessory structure is a detached building subordinate to the main home — a garage, shed, or studio — which may or may not be a dwelling unit.ADU vs Guest HouseADU vs guest house: an ADU is a full dwelling with its own kitchen, while a guest house usually lacks one and can't be a separate residence.Building PermitA building permit is official authorization from a local building department to perform construction, ensuring it meets code.By-Right / Ministerial ApprovalBy-right or ministerial approval grants a permit against objective standards without discretionary review or public hearings.California SB-10California SB-10 is an optional tool letting cities voluntarily upzone parcels up to ten units in transit-rich or urban areas.California SB-9California SB-9 is a ministerial, by-right path letting qualifying single-family lots be split and host up to two units per lot.CasitaA casita is a small standalone secondary dwelling — a regional term for an ADU common in the Southwest and parts of the West.Certificate of OccupancyA certificate of occupancy is a document issued after final inspection confirming a building is safe and legal to occupy.Conditional Use PermitA conditional use permit (CUP) is a discretionary approval allowing a specific use on a property that isn't permitted by right.Detached vs Attached ADUDetached vs attached ADU: a detached ADU is a standalone structure, while an attached ADU shares at least one wall with the main home.EasementAn easement is a recorded right for someone to use part of a property for a set purpose — like utilities or access — that limits where you build.EgressEgress is a code-required safe exit path from a building or room; bedrooms typically need an egress window or door sized for escape and rescue.Floor Area Ratio (FAR)Floor area ratio (FAR) is the ratio of a building's total floor area to the lot size, capping how much can be built.Grading PermitA grading permit authorizes moving, cutting, or filling earth on a site — often required before building on sloped or excavated lots.Height LimitA height limit is the maximum building height zoning allows on a lot, often measured to the roof, with special allowances for ADUs.Impact & Development FeesImpact or development fees are one-time charges on new construction to help fund public infrastructure like roads, water, and parks.JADU vs ADUJADU vs ADU: a JADU is a small unit built inside an existing home's walls, while an ADU can be a larger attached or detached unit.Junior ADU (JADU)A junior ADU (JADU) is a small unit, typically up to 500 sq ft, created within the existing walls of a single-family home.Lot CoverageLot coverage is the share of a lot a building footprint may occupy — a zoning limit that caps ground-level building area on a parcel.Lot Split (Urban Lot Split)An urban lot split is the SB-9 mechanism to divide one qualifying single-family lot into two, each able to hold housing.Missing Middle HousingMissing middle housing is house-scale buildings with multiple units — duplexes, triplexes, fourplexes, and townhouses.Owner-BuilderAn owner-builder is a property owner who acts as their own general contractor on a permitted project instead of hiring one.Permit ValuationPermit valuation is the declared or estimated construction cost of permitted work, used to calculate fees and as a data signal.Plan Check / Plan ReviewPlan check (plan review) is the stage where building department staff examine submitted plans for code compliance before issuing a permit.SetbackA setback is the minimum required distance a building must sit from a property line, street, or another structure.Single-Family ZoningSingle-family zoning is a designation allowing only one detached home per lot — the baseline that recent ADU and lot-split laws relax.Title 24 (CA Energy Code)California Title 24 is the state's building energy-efficiency code, setting insulation, HVAC, and other standards new construction must meet.VarianceA variance is a discretionary approval allowing a property to deviate from a specific zoning rule due to a unique hardship.

Informational only, not legal advice. Housing and permitting rules change and vary by jurisdiction — verify current requirements before relying on anything here.