Every takeoff needs a waste allowance: offcuts, breakage, mistakes, pattern matching and the bag or tin that gets rained on. Too little and you're back at the supplier mid-job. Too much and the profit sits in a pile behind the van.
Typical allowances
| Material | Typical | Go higher when… |
|---|---|---|
| Ready-mix concrete | 5–10% | Uneven base, hand-dug, pumped |
| Bricks and blocks | 5% | Reclaimed brick, many openings or piers |
| Framing timber | 10% | Complex walls, lots of openings |
| Plasterboard | 10–12% | Short walls, sloped ceilings, many openings |
| Laminate / LVP / wood | 7–10% | Diagonal 15%, herringbone 20% |
| Tile | 10% | Large format, diagonal, many cuts: 15%+ |
| Carpet | Varies | Set by the roll width, not a percentage |
| Roof tiles and slates | 10% | Hips, valleys and dormers: 15–20% |
| Deck boards | 10% | Picture frames, diagonal layouts |
| Paint | 5–10% | Rough surfaces, spraying |
| Mulch, gravel, soil | 5–15% | Loose soil settles 15–20% |
Waste isn't only offcuts
Allow for stock length fit. If every run of trim is 3.4 m and you buy 2.4 m lengths, the waste will be far more than 10% unless you plan the joins. Good takeoffs choose stock lengths to suit the runs. The calculators do this for framing, decking and trim.
Keep spares for the client
For tile, flooring and roof coverings, leave a few spares with the client for future repairs. Batches change, and a matching tile three years later can be impossible to find. Say so in your quote. Clients appreciate it.
Track your real waste
The best waste figure is your own. After each job, compare what you ordered with what you used, and adjust your defaults. Every TakeoffYard calculator lets you set the waste allowance per job.
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.