Solve backwards
How much underfloor heating will my screed cover?
- 5 yd³The example worked below
- Heated Screed Volume CalculatorEvery figure is its own
You have
How much heated screed?
That is 5 yd³(3.8 m³). Worked by the Heated Screed Volume Calculator at the settings below.
The settings it uses
- Cover Over the Tube Crown
- 1.75 in
- Tube Outside Diameter
- 0.63 in
- Tube Centres
- 6 in
- Hardened Screed Density
- 131 pcf
- Yield per Bag
- 0.5 ft³
- Waste Allowance (%)
- 10
What it will do
633 sq ft of heated floor
58.8 m²
One heated floor. Enough for a heated floor about 25.2 × 25.2 ft.
Or several. Less than one heated floor of the size the Heated Screed Volume Calculator opens on (a heated floor about 29.3 × 29.3 ft).
Check it forwards
- Heated Floor Area
- 633 sq ft
- It asks for
- 5 yd³
- You have
- 5 yd³
The Heated Screed Volume Calculator asks for 5 yd³ at that size.
If you had more, or less
Around your amount
Each worked by the Heated Screed Volume Calculator at the same settings.
Half
2.5 yd³
316 sq ft
a heated floor about 17.8 × 17.8 ft
Yours
5 yd³
633 sq ft
a heated floor about 25.2 × 25.2 ft
Half as much again
7.5 yd³
949 sq ft
a heated floor about 31 × 31 ft
Double
10 yd³
1,265 sq ft
a heated floor about 36 × 36 ft
Common amounts
What each amount of heated screed covers
The sizes it is usually sold in, each worked by the Heated Screed Volume Calculator at the settings above.
| You have | It covers | As one heated floor | Average heated floors |
|---|---|---|---|
| 1 yd³(0.8 m³) | 127 sq ft(11.8 m²) | a heated floor about 11.2 × 11.2 ft | under 1 |
| 2 yd³(1.5 m³) | 253 sq ft(23.5 m²) | a heated floor about 15.9 × 15.9 ft | under 1 |
| 5 yd³(3.8 m³) | 633 sq ft(58.8 m²) | a heated floor about 25.2 × 25.2 ft | under 1 |
| 10 yd³(7.6 m³) | 1,265 sq ft(118 m²) | a heated floor about 36 × 36 ft | 1 |
Cover over the pipe, then the pipe
The depth that matters is the cover from the top of the pipe to the finished surface; the calculator adds the pipe's own diameter to get the total, so 45 mm over a 16 mm pipe is 61 mm of screed. The pipe displaces a little: at 150 mm centres there are about 6.7 m of pipe to the square metre, taking about 2% of the volume. After ten per cent waste, a cubic metre covers about 15.2 m².
The substrate eats the allowance
The biggest waste term on most floors is not spillage but substrate tolerance: a slab a few millimetres low over part of its area quietly absorbs a real share of the pour. Where the base has been surveyed and is known to be flat, the ten per cent can come down. Where one zone is piped at different centres from the next, run each zone separately, since the displacement differs between them.
Bags or a pump
Bagged screed is counted by its made-up yield — 13 litres a bag by default, a mixed-and-placed figure that moves with the water added. A pumped screed is ordered by volume and mass instead: at 2,100 kg/m³ the calculator's 80 m² floor is about 11 tonnes. Cover depth comes from EN 1264 or the heating supplier, and BS 8204 covers thickness and soundness; edge strip and movement joints are separate.
How the answer is worked
Nothing here is a second formula. The Heated Screed Volume Calculator runs forwards — a size in, a quantity out — and this page grows its own starting heated floor 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.
Heated Screed Volume Calculator
runs it forwardsScreed quantity for an underfloor heating build-up, taking the cover over the tube crown and subtracting what the tube itself displaces.
Work out what to buy insteadSolve backwards
Other things you might already have
How big a bed will my bags of mulch cover?
Bagged mulch, worked by the Mulch Calculator.
How much bed will a yard of mulch cover?
Bulk mulch, worked by the Mulch & Gravel Calculator.
How much ground will my gravel cover?
Gravel, worked by the Mulch & Gravel Calculator.
How big a bed will my topsoil fill?
Topsoil, worked by the Topsoil Calculator.
How big a raised bed will my soil fill?
Raised bed soil, worked by the Garden Soil Calculator.
How much ground will my compost dress?
Compost, worked by the Compost Blend Calculator.
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 heated floor does 5 yd³ of heated screed cover?
- At the Heated Screed Volume Calculator's own settings, 633 sq ft (58.8 m²) — a heated floor about 25.2 × 25.2 ft. Every figure follows the settings, which you can change in the calculator.
- How much heated floor does 5 m³ of heated screed cover?
- At the Heated Screed Volume Calculator's own settings, 76.2 m² (820 sq ft) — a heated floor about 8.7 × 8.7 m. Every figure follows the settings, which you can change in the calculator.
- How thick should screed be over underfloor heating?
- The cover over the pipe is what is specified; the calculator opens at 45 mm (1¾ in) over a 16 mm pipe, 61 mm in all. Take the figure for your screed type from EN 1264 or the heating system supplier rather than a general rule — flowing and sand-cement screeds are specified differently.
- How much screed do I need for 50 m² of underfloor heating?
- At 45 mm over a 16 mm pipe at 150 mm centres, with ten per cent waste, about 3.28 m³ (4.3 cubic yards) — about 6.9 tonnes at 2,100 kg/m³, or 253 bags at 13 litres made-up yield. A base with low spots takes more than the allowance.
- Does underfloor heating pipe reduce the screed needed?
- A little. The calculator takes the pipe's volume out: a 16 mm pipe at 150 mm centres runs about 6.7 m to the square metre and displaces about 2% of a 61 mm screed. Tighter centres near outside walls displace more; where a zone is split into two spacings, calculate them separately.