Flooring estimates fail in two ways: too little pattern waste for hard floors, and treating carpet as an area when it comes off a roll of fixed width.
Hard flooring: boxes
Measure the room to the walls, including under fitted appliances if the floor runs underneath. Add waste for the layout, divide by the box coverage, and round up to whole boxes.
| Layout | Waste |
|---|---|
| Straight, simple room | 7% |
| Straight, many cuts / small rooms | 10% |
| Diagonal | 15% |
| Herringbone / chevron | 20% |
Carpet: roll width rules
Carpet comes in fixed widths: 4 m and 5 m are standard. You buy a length off the roll, so a room just wider than the roll needs a second strip, and the waste can be large. Always check both directions and pick the one with the least waste and seams in sensible places.
Underlay
Underlay follows the floor area plus a small allowance. Some LVP and engineered floors have it attached. Check before adding a separate one.
The extras
- Leveller for floors that aren't flat enough for the product
- Moisture barrier over concrete
- Door bars, thresholds and stair nosings
- Skirting or scotia to cover the expansion gap
- Gripper and seam tape for carpet
- Uplift and disposal of the old floor
This guide is general information for estimating. It is not engineering, legal or tax advice. Check the Building Regulations and Building Control for your project.