Solve backwards
How much shower wall will my backer boards cover?
- 18 boardsThe example worked below
- Tile Backer Board CalculatorEvery figure is its own
You have
How much backer board?
Worked by the Tile Backer Board Calculator at the settings below.
The settings it uses
- Board size
- 4 ft × 32 in (10.6 sq ft)
- Cutting waste (%)
- 15
What it will do
167 sq ft of tile backer
15.5 m²
One shower wall. Enough for a shower wall 20.8 ft long and 8 ft high.
Or several. About 1 shower wall of the size the Tile Backer Board Calculator opens on: a shower wall 20 ft long and 8 ft high.
Check it forwards
- Area to board
- 167 sq ft
- It asks for
- 18 boards
- You have
- 18 boards
The Tile Backer Board Calculator asks for 18 boards at that size, and 19 boards one step larger.
If you had more, or less
Around your amount
Each worked by the Tile Backer Board Calculator at the same settings.
Half
9 boards
83.4 sq ft
a shower wall 10.4 ft long and 8 ft high
Yours
18 boards
167 sq ft
a shower wall 20.8 ft long and 8 ft high
Half as much again
27 boards
250 sq ft
a shower wall 31.3 ft long and 8 ft high
Double
36 boards
334 sq ft
a shower wall 41.7 ft long and 8 ft high
Common amounts
What each amount of backer board covers
The sizes it is usually sold in, each worked by the Tile Backer Board Calculator at the settings above.
| You have | It covers | As one shower wall | Average shower walls |
|---|---|---|---|
| 5 boards | 46.3 sq ft(4.3 m²) | a shower wall 5.8 ft long and 8 ft high | under 1 |
| 10 boards | 92.7 sq ft(8.61 m²) | a shower wall 11.6 ft long and 8 ft high | under 1 |
| 18 boards | 167 sq ft(15.5 m²) | a shower wall 20.8 ft long and 8 ft high | 1 |
| 30 boards | 278 sq ft(25.8 m²) | a shower wall 34.7 ft long and 8 ft high | 1 |
Fifteen per cent in a bathroom
The calculator carries fifteen per cent for cuts, realistic in a bathroom where every board meets a window, a door or a fitting; on a plain floor ten is enough. Read backwards, it comes off what you have, so the boards cover less than their face. Deduct openings over about a square metre; below that the cutting waste eats the saving.
Stop the boarding where the tile stops
Measure the area to be boarded to where the boarding stops, not the room: a wet-area board that runs 150 mm past the shower enclosure stops there, and the rest of the wall is plasterboard. Smaller boards are easier to handle in a bathroom and leave more joints to tape; on a large floor larger sheets are worth it.
A substrate, not a waterproofing layer
Backer board is not waterproof on its own — a wet area needs a membrane or a liquid-applied system over it, a separate material. Boards are screwed at about 200 mm (8 in) centres and the joints taped with alkali-resistant mesh set in the tile mortar; on floors they are bedded in mortar over a sound deck, not just screwed.
How the answer is worked
Nothing here is a second formula. The Tile Backer Board Calculator runs forwards — a size in, a quantity out — and this page grows its own starting shower wall 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.
Tile Backer Board Calculator
runs it forwardsCount cement backer boards, screws and joint tape for a tiled wet area.
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 tile backer does 18 boards of backer board cover?
- At the Tile Backer Board Calculator's own settings, 167 sq ft (15.5 m²) — a shower wall 20.8 ft long and 8 ft high. That is about 1 shower wall of the size the calculator opens on: a shower wall 20 ft long and 8 ft high. Every figure follows the settings, which you can change in the calculator.
- How many square feet does a sheet of cement board cover?
- A 4 foot by 32 inch board covers about 10.6 square feet (0.99 m²), a 3 by 5 foot board 15 square feet (1.4 m²), and a 1200 by 800 mm board 0.96 m² (10.3 square feet). With fifteen per cent for bathroom cuts, a 4 foot by 32 inch board backs about 9 square feet of tiled wall.
- Is cement backer board waterproof?
- No. It is water-resistant — it will not rot or swell — but water passes through it. A shower or wet area needs a waterproofing membrane or a liquid-applied system over the board, installed to the product's instructions, before the tile goes on.
- How far apart should backer board screws be?
- About 200 mm (8 inches) on centre through the field and at the edges, per manufacturer instructions and the TCNA Handbook, using the corrosion-resistant screws made for the board. Joints are taped with alkali-resistant mesh and filled with the same mortar used to set the tile.