40 sq ft of floor needs 3 sheets of HardieBacker ¼ (3×5 ft), about 159 screws and 1 bag of thinset underneath.
| Board | Sheets | Fasteners | Cost |
|---|---|---|---|
| HardieBacker ¼ (3×5) | 3 | 159 | $74.05 |
| HardieBacker 500 (3×5) | 3 | 159 | $86.35 |
| Durock ¼ (3×5) | 3 | 159 | $71.35 |
| Durock ½ (3×5) | 3 | 159 | $81.40 |
| Durock ⅝ (3×5) | 3 | 159 | $96.85 |
| GoBoard 3×5 (3×5) | 3 | 159 | — |
| GoBoard 4×8 (4×8) | 2 | 126 | — |
| wedi 3×5 (3×5) | 3 | 44 | $207 |
| wedi 4×8 (4×8) | 2 | 44 | $337 |
Floor & Decor prices checked October 2026; wedi at August 2026 list.
| Board | Sheets | Fasteners | Cost |
|---|---|---|---|
| HardieBacker ¼ (3×5) | 3 | 159 | $74.05 |
| HardieBacker 500 (3×5) | 3 | 159 | $86.35 |
| Durock ¼ (3×5) | 3 | 159 | $71.35 |
| Durock ½ (3×5) | 3 | 159 | $81.40 |
| Durock ⅝ (3×5) | 3 | 159 | $96.85 |
| GoBoard 3×5 (3×5) | 3 | 159 | — |
| GoBoard 4×8 (4×8) | 2 | 126 | — |
| wedi 3×5 (3×5) | 3 | 44 | $207 |
| wedi 4×8 (4×8) | 2 | 44 | $337 |
On a floor, 1/4 in board is enough: it adds no strength, it just gives the tile a stable, non-wood surface. The subfloor itself must be stiff enough for tile.
The full method, material data and tips are on the main backer board calculator page.