Setbacks, Yards, and Build-To Lines
Summary
A setback is the minimum distance a building must sit back from a lot line, street, or other protected feature, and a yard is the open area that results; a build-to line works the other way by requiring the building to meet a line at the street. Together they define the buildable envelope on the plan, so measure them from the right line before testing a massing.
Cols
Scope
- Setback distances and yard definitions are set by each local ordinance and by private covenants. Always verify the municipal code's definitions and the current zoning for the project parcel
- Covers how setbacks are defined and measured, how lot type changes the yards, and how they combine into a buildable envelope
- Fire separation distances in the building code can require more distance or rated walls; they are in the IBC and IRC notes
Terminology
- Setback: the minimum distance a building or structure must be set back from a street or road, a river or stream, a shore or flood plain, or another place deemed to need protection
- Front yard, side yard, rear yard: the open areas between the building and the front, side, and rear lot lines; the side yard runs between the building and the side lot line from the front yard to the rear yard, and the rear yard is opposite the front yard
- Required yard: the area that must remain open under the setback
- Build-to line: a line at which the building face must be located (or must cover a set percentage), instead of being set back
- Corner lot: a lot on two streets; some codes give it two front yards, and others assign the front to the shorter street frontage
- Through lot: a lot with street frontage on two opposite sides, usually with no rear yard
- Flag lot: a lot reached by a narrow strip; the front lot line is the line separating the lot from the right-of-way or access easement
- Right-of-way: land dedicated to a street or public use; some codes measure setbacks from it
- Easement: the right of another party to use part of a lot, such as a utility easement
- Encroachment (projection): an element such as an eave, porch, or step extending into a required yard
Requirements
Who sets setbacks and why
- Local governments set setbacks by ordinance, zoning, and building code, mainly for safety, privacy, and environmental protection
- Private developers set uniform lines in covenants and restrictions to keep a consistent street appearance and prevent crowding; building ahead of a line may need special approval
- Setbacks also provide room for utilities and utility meter access
Measuring
- Measure to the line the ordinance names: in some municipalities setbacks are measured from the street right-of-way rather than the front property line
- Corner, through, and flag lots are the places where definitions change; ask the planning staff which lines are front, side, and rear
- Setbacks can also apply to features other than buildings, such as fences, landscaping, and septic tanks, depending on the jurisdiction
Build-to lines
- A build-to line controls where the front of the building sits, often with a requirement that a set percentage of the frontage meet it
- Urban and mixed-use districts use build-to ranges to hold the street wall; the range is a minimum and a maximum distance from the line
- A build-to line may replace the front setback or work with it
Historic ranges
- Neighborhoods built before 1890 commonly have one to five feet between properties; suburbs laid out before 1920 commonly have five to fifteen feet between houses
- Modern setbacks grew with car ownership and zoning; some areas have recently reduced them
Worked examples
Buildable envelope
An illustrative R-1 lot, 60 ft by 120 ft (7,200 sq ft), with a front setback of 20 ft, side setbacks of 5 ft each, and a rear setback of 20 ft.
| Step | Calculation | Result |
|---|---|---|
| Buildable width | 60 − (5 + 5) | 50 ft |
| Buildable depth | 120 − (20 + 20) | 80 ft |
| Envelope area | 50 × 80 | 4,000 sq ft |
| Coverage cap at 40 percent | 7,200 × 0.40 | 2,880 sq ft |
| Governing limit | Smaller of the two | Coverage governs at 2,880 sq ft |
Corner lot
The same lot sits on a corner, with the code treating both street sides as front yards at 20 ft.
| Step | Calculation | Result |
|---|---|---|
| Buildable width | 60 − (20 + 5) | 35 ft |
| Buildable depth | 120 − (20 + 20) | 80 ft |
| Envelope area | 35 × 80 | 2,800 sq ft |
| Effect | Envelope drops 1,200 sq ft | Corner lots cost buildable area |
Build-to range
A mixed-use district sets a build-to range of 5 ft to 15 ft from the right-of-way for 70 percent of the frontage.
| Step | Calculation | Result |
|---|---|---|
| Frontage | 100 ft | 70 ft of facade must lie in the range |
| Remaining | 30 ft | May sit deeper, such as at a courtyard or entry |
| Check | Distance measured from the right-of-way line | Not the curb or the property line |
Coordination
- Survey: get lot lines, right-of-way, and easements from a current boundary survey
- Title and covenants: recorded plats may show build lines or easements tighter than the ordinance
- Fire code: the building code requires rated walls or limits openings near lot lines; the larger of the zoning and code distances sets the design
- Utilities and services: meters, transformers, and utility easements take space in the yard
- Site design: driveways, parking, and landscaping fit inside the yards and may have their own setbacks
- Planning staff: corner lot, flag lot, and projection rules vary; confirm early
Common issues
- Measuring from the wrong line: from the property line instead of the right-of-way (or the reverse)
- Easements inside the setback: an easement may block building even where zoning allows it
- Projections ignored: eaves, bay windows, porches, and steps may need to be within allowed encroachments
- Corner lot assumptions: the second street side may be a front yard
- Mailbox and driveway items: some items have maximum rather than minimum setbacks
- Existing buildings: an addition to a building that already encroaches may have special rules
Standards
- Local zoning ordinance: the yard definitions and setback tables
- Recorded plat and covenants: private building lines
Sources
- Wikipedia: Setback (land use), https://en.wikipedia.org/wiki/Setback_(land_use)
- Fairfax County: yard and lot determination, https://www.fairfaxcounty.gov/code/sites/code/files/assets/documents/pdf/yard_and_lot_determination.pdf
- City of Richmond: zoning illustrations, https://Rva.gov/sites/default/files/Planning/PDFDocuments/Zoning/Zoning_Illustrations.pdf