Calculateur de Ratio d'Emprise au Sol — Formule
## Lot Coverage Ratio
Lot coverage measures how much of a parcel is covered by buildings and impervious surfaces. Zoning codes use coverage limits to control density, manage stormwater, and preserve neighborhood character.
### Building Coverage Ratio
**Building Coverage = Building Footprint / Lot Area x 100**
This measures only the building footprint (first floor area), not total floor area.
### Impervious Coverage Ratio
**Impervious Coverage = Total Impervious Surfaces / Lot Area x 100**
Includes buildings, driveways, patios, walkways, and any surface that prevents water absorption.
### Why Coverage Matters
- **Zoning compliance**: Most zones cap building coverage at 25-50% and impervious at 50-75%
- **Stormwater management**: Higher impervious coverage increases runoff and may require detention facilities
- **Neighborhood character**: Coverage limits prevent oversized buildings on small lots
- **Permitting**: Exceeding coverage limits requires a variance, which is not guaranteed
Lot coverage measures how much of a parcel is covered by buildings and impervious surfaces. Zoning codes use coverage limits to control density, manage stormwater, and preserve neighborhood character.
### Building Coverage Ratio
**Building Coverage = Building Footprint / Lot Area x 100**
This measures only the building footprint (first floor area), not total floor area.
### Impervious Coverage Ratio
**Impervious Coverage = Total Impervious Surfaces / Lot Area x 100**
Includes buildings, driveways, patios, walkways, and any surface that prevents water absorption.
### Why Coverage Matters
- **Zoning compliance**: Most zones cap building coverage at 25-50% and impervious at 50-75%
- **Stormwater management**: Higher impervious coverage increases runoff and may require detention facilities
- **Neighborhood character**: Coverage limits prevent oversized buildings on small lots
- **Permitting**: Exceeding coverage limits requires a variance, which is not guaranteed
Exemple Résolu
10,000 sq ft lot, 2,500 sq ft building footprint, 800 sq ft driveway/patio, 200 sq ft other impervious, 35% max building coverage, 60% max impervious.
- Building coverage: 2,500 / 10,000 = 25.0%
- Total impervious: 2,500 + 800 + 200 = 3,500 sq ft
- Impervious coverage: 3,500 / 10,000 = 35.0%
- Remaining building capacity: 3,500 - 2,500 = 1,000 sq ft
- Remaining impervious: 6,000 - 3,500 = 2,500 sq ft
- Open space: 10,000 - 3,500 = 6,500 sq ft (65.0%)