Reference Charts

Quick lookup tables for common planning questions. For interactive numbers, use the linked calculator.

Concrete slab thickness

| Use | Typical thickness | |-----|-------------------| | Walkway / patio (foot traffic) | 4 in / 100 mm | | Driveway (cars) | 4–6 in / 100–150 mm | | Garage slab | 4–6 in | | Post footing (frost depth varies) | Below local frost line |

Gravel layer depth

| Use | Depth | |-----|-------| | Paver bedding sand | 1–2 in / 25–50 mm | | Gravel sub-base under patio | 4–6 in / 100–150 mm | | Driveway sub-base | 6–8 in / 150–200 mm |

Mulch depth

| Use | Depth | |-----|-------| | Flower beds | 2–3 in / 5–7.5 cm | | Trees (donut, not volcano) | 2–4 in away from trunk |

Paint coats

| Situation | Coats | |-----------|-------| | Same colour refresh | 1 | | Colour change | 2 | | Dark → light | 2–3 |

Unit conversions

| US | Metric | |----|--------| | 1 ft³ | 0.0283 m³ | | 1 yd³ | 0.765 m³ | | 1 ft² | 0.0929 m² | | 1 ton (US) | 0.907 tonnes |

Roofing pitch factor (US)

Pitch factor = √(1 + (rise ÷ 12)²). Example: 6/12 → factor ≈ 1.118.

See the Roofing Calculator for your footprint.