Reference Charts
Quick lookup tables for common planning questions on Project Home Calc. These charts are starting points — local code, soil, and product labels still win. For interactive numbers with waste and cost bands, open the linked calculator.
How to use these charts
Pick the row that matches the job, then re-run the matching calculator with your length, width, and depth. A chart cannot see your access path, frost line, or dye lot — it only keeps you from starting with an empty guess.
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 | | Shed pad (light storage) | 4 in / 100 mm | | Post footing (frost depth varies) | Below local frost line |
Thicker slabs jump volume fast: going from 4 in to 6 in is a 50% increase for the same footprint. Confirm with the Concrete Calculator before you compare quotes.
Gravel and sand 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 | | Path topping (decorative gravel) | 2–3 in / 50–75 mm |
Bedding sand and gravel base are separate orders. See the Gravel Calculator and Sand Calculator.
Mulch and topsoil depth
| Use | Depth | |-----|-------| | Flower beds (mulch) | 2–3 in / 5–7.5 cm | | Trees (donut, not volcano) | 2–4 in away from trunk | | New planting bed (topsoil) | 4–6 in / 10–15 cm | | Lawn topdressing | ½–1 in / 1–2.5 cm |
Bulk delivery usually wins past about one cubic yard. Use the Mulch and Topsoil tools for tonnage.
Paint coats
| Situation | Coats | |-----------|-------| | Same colour refresh | 1 | | Colour change | 2 | | Dark → light | 2–3 | | Bare plaster / patched walls | Primer + 2 |
Coverage on the tin assumes ideal conditions. Rough surfaces and deep colour changes burn more paint — see the Paint Calculator.
Waste allowances (planning defaults)
| Job | Common planning waste | |-----|------------------------| | Simple rectangular flooring | 5–8% | | Diagonal tile or herringbone pavers | 12–15% | | Straight fence panel run | 1 spare panel on long runs | | Asphalt roof field (simple gable) | ~10% | | Brick wall (solid rectangle) | 5–10% |
Edit waste in each calculator — these rows are defaults, not rules.
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 | | 1 gallon (US) | 3.785 litres |
Roofing pitch factor (US)
Pitch factor = √(1 + (rise ÷ 12)²). Example: 6/12 → factor ≈ 1.118.
One US roofing square = 100 ft² of roof area. Bundle counts depend on the product — see How to read a roofing square and the Roofing Calculator.
Brick and mortar (rule of thumb)
| Item | Planning note | |------|----------------| | US modular brick | Often ~7 per ft² of wall face with mortar joints | | UK metric brick | Often ~60 per m² of single-leaf wall | | Premixed mortar bags | Roughly 1 bag per ~100–120 bricks for standard joints |
Confirm brick size on the pallet label. Guides: How many bricks for a garden wall and Mortar quantities.