Jobsite Numbers Card — Stair Limits, Roof Pitch, Grades & Spacing Rules
One-page jobsite card: IBC/IRC/OSHA stair limits, roof pitch classes in degrees, IRC drainage grades, and guard and outlet spacing rules.
Updated August 20, 2026
The code numbers a jobsite argument reaches for, on one printable card: maximum riser and minimum tread under IBC, IRC, and OSHA with the Blondel comfort band, the roof pitch classes with their angles in degrees, the IRC foundation drainage grades for pervious and impervious surfaces, the guard opening sphere rule, and the NEC receptacle spacing distances for walls and countertops.
Every cell is generated from the constants behind the stair designer, roof pitch, grading slope, baluster spacing, and outlet spacing calculators — degrees are computed from the rise-per-12 boundaries, and metric equivalents from the exact inch definition, never retyped. The linked calculators apply these limits to real geometry and count the fixtures for you.
Jobsite Numbers Card — Stair Limits, Roof Pitch, Grades & Spacing Rules — updated August 20, 2026
Stair limits (IBC / IRC / OSHA)
| Rule | Imperial | Metric |
|---|---|---|
| IBC 1011.5.2 — max riser | 7 in | 178 mm |
| IBC 1011.5.2 — min tread | 11 in | 279 mm |
| IRC R311.7.5 — max riser | 7.75 in | 196 mm |
| IRC R311.7.5 — min tread | 10 in | 254 mm |
| OSHA 1910.25 — max riser | 9.5 in | 241 mm |
| OSHA 1910.25 — min tread | 9.5 in | 241 mm |
| Comfort band, 2R + T (Blondel) | 24–25 in | 610–635 mm |
| Blondel target for auto tread (2R + T) | 25 in | 630 mm |
Residential (IRC) vs commercial (IBC) vs general-industry (OSHA) presets from the stair designer; headroom and other comfort checks live in the tool.
Roof pitch classes
| Class | Pitch (x/12) | Degrees |
|---|---|---|
| Flat | < 2/12 | < 9.5° |
| Low slope | 2/12 – 4/12 | 9.5° – 18.4° |
| Conventional | 4/12 – 9/12 | 18.4° – 36.9° |
| Steep | > 9/12 | > 36.9° |
Degrees computed as atan(rise ⁄ 12). Shingle manufacturers set their own low-slope underlayment cutoffs — check the wrapper.
Drainage grades (IRC R401.3)
| Surface | Rule | Rate |
|---|---|---|
| Pervious (soil) | 6 in fall in first 10 ft | 5% (0.60 in/ft) |
| Impervious (paved) | 2% min slope (Exception) | 2% (0.24 in/ft) |
Fall away from the foundation. Where lots prevent 10 ft, drains or swales must carry the water (R401.3).
Guard openings (IRC R312.1.3)
| Location | Max clear opening |
|---|---|
| Guard infill (balusters) | 4 in sphere must not pass (102 mm) |
Measured as the sphere that must not pass anywhere in the infill; the baluster spacing calculator solves the even layout.
Receptacle spacing (NEC 210.52)
| Location | Max from any point | Max spacing |
|---|---|---|
| Wall line (210.52(A)) | 6 ft | 12 ft |
| Countertop (210.52(C)) | 24 in | 48 in |
Max spacing is twice the point distance. Wall spaces ≥ 2 ft count; counter segments ≥ 12 in count — the outlet spacing calculator does the counting.
Sources
- IBC 1011.5.2 / IRC R311.7.5 / OSHA 1910.25 stair dimension limits
- US rise-per-12 pitch convention (degrees computed)
- IRC R401.3 and Exception (foundation drainage)
- IRC R312.1.3 guard opening sphere rule
- NEC 210.52(A) and (C) receptacle placement
Try the Calculators
Jobsite Numbers Card — Stair Limits, Roof Pitch, Grades & Spacing Rules — reuven.tools/cheat-sheets/jobsite-numbers-card — verified against: IBC 1011.5.2 / IRC R311.7.5 / OSHA 1910.25 stair dimension limits; US rise-per-12 pitch convention (degrees computed); IRC R401.3 and Exception (foundation drainage); IRC R312.1.3 guard opening sphere rule; NEC 210.52(A) and (C) receptacle placement