Fire separation distance
Dimensions measured perpendicular from each face of the building to the lot line, street centerline, or an imaginary line between buildings on the same lot.
Plan check correction · Fire and life safety
Plan check correction: fire separation distance and exterior wall openings
Buildings close to a property line draw this comment. The distance sets both the rating of the exterior wall and how much of it can be windows and doors.
The comment asks you to dimension the fire separation distance from each exterior wall to the lot line, or to the centerline of a street or an imaginary line between buildings, and show that the wall rating and opening area meet the limits for that distance. Clear it with dimensioned site and floor plans and an opening-area calculation on the elevations.
Read the comment
What the plans examiner is asking for
Exterior wall rating
The rating each wall needs for its distance, occupancy, and construction type under IBC Section 705.5 and Table 705.5.
Opening area
Allowable unprotected and protected opening area for the distance under IBC Section 705.9 and Table 705.9, with the actual area calculated per story.
Projections
Eaves, balconies, and other projections checked for their distance to the line.
Published correction lists
How city lists word this correction
Published lists ask for fire separation distance dimensions, exterior wall ratings, or the percentage of openings. Paraphrased from each department’s own published list; the lists do not rank items by how often they are issued.
| City | What the published list asks for | Code cited | Where it appears |
|---|---|---|---|
| Los Angeles | Show fire separation distance to interior lot lines, to the centerline of streets, alleys or public ways, and to imaginary lines between buildings, measured perpendicular to the wall. | CBC 202 | Commercial Plan Check Correction Sheets (2026 LABC), Part II, E. Fire-Resistance Rated Construction, item 2 |
| San Francisco | Plot plan must locate the building, adjoining buildings and public ways with real and assumed property lines to support exterior wall and opening protection review. | SFBC 106A.3.4.2.1, item 3c | SFBC 106A.3.4.2.1 Contents of site permit application, item 3c |
| San Diego | The site plan must dimension fire separation distance between adjoining buildings and from property lines to every building or structure. | — | Project Submittal Manual Section 2, checklist item 4.1.10 (Fire Separation Distances) |
Sources reviewed September 12, 2026. Code sections are as cited on each list and follow that city’s adopted code. Confirm the current list and edition with the department.
Revise the set
What changes on the drawings, and what else to re-check
Opening limits change elevations, and rating changes reach the wall assembly and its details.
| Change | Sheets to revise | Also re-check |
|---|---|---|
| Distances dimensioned | Site plan; floor plans | Survey basis, setbacks on zoning sheets, imaginary lines between buildings |
| Exterior wall rated | Wall types; wall sections | Listed assembly for exterior walls, eave and soffit construction, vents in the wall |
| Openings reduced or protected | Elevations with opening area table; window schedule | Daylight and energy calculations, rated glazing, sprinkler protection of openings |
| Projection cut back | Roof plan; wall sections | Drainage, structural framing, architectural elevations |
Close the comment
A response the reviewer can verify
An illustrative example written for this guide, not a real project or a city’s wording. Name the sheet, the detail, and the change, so the recheck does not start with a search.
Comment
Show fire separation distance to property lines. Provide exterior wall ratings and allowable opening percentages for the north and east walls.
Response
Revised as requested. Fire separation distances are dimensioned on A1.01 (north wall 6 feet 2 inches, east wall 12 feet). Both walls revised to one-hour construction (wall type EW2 on A0.20). Opening area tables on elevations A4.01 and A4.02 show 14 percent unprotected openings on the east wall and 9 percent on the north wall, within the allowable for those distances.
Before you submit
Catch it before the plans examiner does
Dimension from the right line
Measure to the lot line, street centerline, or imaginary line, and say which one on the plan.
Tabulate per story
Calculate opening area on each story of each wall that is within the limited distance.
Check the eaves
Look at roof overhangs and balconies, which sit closer to the line than the wall.
Groundbook compares the drawings, schedules, and specifications with the code and local references you upload, and links each potential issue to the sheets and sections behind it. Your team verifies each finding; the jurisdiction makes every approval decision. See the pre-permit review and drawing-to-code review.
Questions, answered
Fire separation distance: questions
How is fire separation distance measured?
Perpendicular from the face of the building to the closest interior lot line, the centerline of a street or public way, or an imaginary line between two buildings on the same lot.
Is fire separation distance the same as a zoning setback?
No. A zoning setback is a planning rule for where a building can sit. Fire separation distance is a building code measurement that sets exterior wall ratings and opening limits.
Do sprinklers change the allowable openings?
Yes. In IBC Table 705.9 the allowable percentage rises when the building is sprinklered throughout or when the openings are protected; either condition is enough. State the basis on the elevations.
Keep going
Related corrections and city guides
Fire-rated assemblies
The rating each wall, floor, and roof needs, a tested or listed design for each, and plans that show the ratings consistently.
Read this correctionRated openings and penetrations
Doors, glazing, dampers, and penetrations in rated assemblies shown with the protection each needs.
Read this correctionCode analysis
Occupancy, construction type, allowable area, occupant load, and sprinkler basis stated on the cover sheet and consistent with the plans.
Read this correctionLos Angeles plan check
How LADBS reviews a permit set and what its published lists ask for.
Open the city guideSan Francisco plan check
How DBI reviews a permit set and what its published lists ask for.
Open the city guideSan Diego plan check
How DSD reviews a permit set and what its published lists ask for.
Open the city guideRespond to plan check comments
Response letter format, six response types, and a free response log.
Read the guideFind the corrections before the plans examiner does
Upload the drawing set with the code and local references that govern it. Groundbook links each potential issue to its sources for your team to verify.