Solve backwards
How much green roof will my growing medium cover?
- 5 yd³The example worked below
- Green Roof Growing Medium Volume CalculatorEvery figure is its own
You have
How much green roof growing medium?
That is 5 yd³(3.8 m³). Worked by the Green Roof Growing Medium Volume Calculator at the settings below.
The settings it uses
- Growing Medium Depth
- 6 in
What it will do
270 sq ft of green roof
25.1 m²
One green roof. Enough for a green roof about 16.4 × 16.4 ft.
Or several. Less than one green roof of the size the Green Roof Growing Medium Volume Calculator opens on (a green roof about 33 × 33 ft).
Check it forwards
- Green Roof Area
- 270 sq ft
- It asks for
- 5 yd³
- You have
- 5 yd³
The Green Roof Growing Medium Volume Calculator asks for 5 yd³ at that size.
If you had more, or less
Around your amount
Each worked by the Green Roof Growing Medium Volume Calculator at the same settings.
Half
2.5 yd³
135 sq ft
a green roof about 11.6 × 11.6 ft
Yours
5 yd³
270 sq ft
a green roof about 16.4 × 16.4 ft
Half as much again
7.5 yd³
405 sq ft
a green roof about 20.1 × 20.1 ft
Double
10 yd³
540 sq ft
a green roof about 23.2 × 23.2 ft
Common amounts
What each amount of green roof growing medium covers
The sizes it is usually sold in, each worked by the Green Roof Growing Medium Volume Calculator at the settings above.
| You have | It covers | As one green roof | Average green roofs |
|---|---|---|---|
| 1 yd³(0.8 m³) | 54 sq ft(5.02 m²) | a green roof about 7.3 × 7.3 ft | under 1 |
| 5 yd³(3.8 m³) | 270 sq ft(25.1 m²) | a green roof about 16.4 × 16.4 ft | under 1 |
| 10 yd³(7.6 m³) | 540 sq ft(50.2 m²) | a green roof about 23.2 × 23.2 ft | under 1 |
| 20 yd³(15.3 m³) | 1,080 sq ft(100 m²) | a green roof about 33 × 33 ft | 1 |
Depth is the design decision
Extensive green roofs commonly use 75 to 150 mm (3 to 6 in) of growing medium, and intensive, garden-style roofs 300 mm (12 in) or more. At 150 mm a cubic metre covers 6.7 m² (72 square feet), and at 6 inches a cubic yard covers 54 square feet (5 m²). Halve the depth and the same volume covers twice the roof, so confirm the design depth from the specification first.
Plan area is not planted area
A green roof carries vegetation-free zones: a ballast or paver border at the parapet and every roof edge, commonly 300 to 500 mm (12 to 20 in) wide, and a clear ring around rooflights, upstands, penetrations and any maintenance path. Those take gravel or slab, not substrate, so deduct them from the roof before setting what you have against it — and resist filling them with growing medium.
Substrate, not topsoil
Green roof substrate is an engineered mineral blend to a specified grading with a small organic fraction. Screened topsoil at the same depth is a different product — heavier when saturated, which moves the structural figure, and fine enough to blind the filter fleece. The build-up beneath it, from root barrier and protection mat to drainage board and fleece, adds depth every upstand and threshold must clear.
How the answer is worked
Nothing here is a second formula. The Green Roof Growing Medium Volume Calculator runs forwards — a size in, a quantity out — and this page grows its own starting green roof in proportion until the quantity it asks for is what you have. Where it rounds up to whole containers, the answer is the largest size before the next one would be needed.
Where the calculator adds an allowance for cuts or breakage when you order, the same allowance comes off here, because it is the same calculator: a stack you already own finishes less than its face value. Where it adds none, neither does this page — the settings beside the answer say which.
Green Roof Growing Medium Volume Calculator
runs it forwardsCalculate the volume of growing medium (substrate) needed to fill a green roof to its design depth.
Work out what to buy insteadSolve backwards
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Solve backwards
Start from what is already in the yard
Paint, sheets, rolls, bags and pieces, each read the other way by the calculator that orders it.
The calculator's own figures
Nothing is estimated twice: the page runs the same calculator you would order with.
The largest size that fits
Where a calculator rounds up to whole containers, the answer stops before the next one.
Both unit systems
Gallons and litres, square feet and square metres, side by side.
Frequently asked questions
- How much green roof does 5 yd³ of green roof growing medium cover?
- At the Green Roof Growing Medium Volume Calculator's own settings, 270 sq ft (25.1 m²) — a green roof about 16.4 × 16.4 ft. Every figure follows the settings, which you can change in the calculator.
- How much green roof does 5 m³ of green roof growing medium cover?
- At the Green Roof Growing Medium Volume Calculator's own settings, 33.3 m² (359 sq ft) — a green roof about 5.8 × 5.8 m. Every figure follows the settings, which you can change in the calculator.
- How deep should green roof substrate be?
- Extensive green roofs commonly use 75 to 150 mm (3 to 6 in) of growing medium, and intensive, garden-style roofs 300 mm (12 in) or more. The design depth comes from the landscape architect's or the system maker's specification, and it sets both what can be planted and the load on the roof.
- How many cubic metres of substrate for a 100 m² green roof?
- At 150 mm, 100 m² takes 15 m³; at 100 mm, 10 m³; at 75 mm, 7.5 m³ — before deducting the vegetation-free border and the clear zones. In imperial, 1,000 square feet at 6 inches is about 18.5 cubic yards.
- Can I use topsoil on a green roof?
- Not as a substitute. Green roof substrate is an engineered mineral blend with a small organic fraction; topsoil is heavier when saturated, which changes the load on the roof, and fine enough to clog the filter fleece and hold water where the design wants it drained. Order the specified product, not a volume of anything.