Waste allowance: how much extra material to buy

Last reviewed 2026-06-06

The single most common reason DIYers run short. Here is how much extra to buy for tile, flooring, decking and pavers — and why.

A “waste allowance” is the small percentage of extra material you buy beyond the exact area, to cover the offcuts, breakages and mistakes that every real project produces. Skip it and you will almost certainly run short — usually right at the end, and often after the product has changed batch or been discontinued.

Why waste is unavoidable

• Cuts: tiles, planks and boards have to be cut to fit edges, and the offcut is often too small to reuse.
• Breakage: tiles crack, planks split, and a few pieces simply arrive damaged.
• Pattern and direction: matching a pattern or grain wastes material at every join.
• Mistakes: even careful people miscut. A buffer turns a disaster into a shrug.

How much to add

• Tile: about 10% for a straight layout, 15% for diagonal or herringbone, up to 20% for small rooms with many cuts.
• Flooring (laminate, vinyl, hardwood): around 10% standard; 5% for a large simple room, 15% for diagonal installs.
• Decking: about 10%, more if you have a picture-frame border or angled boards.
• Pavers: around 5% for a running-bond layout, 10% for diagonals and curves.

Our tile, flooring, deck and paver calculators let you pick the waste percentage and fold it into the final quantity automatically, so you never have to do the maths by hand.

Buy it all in one batch

This matters as much as the percentage. Tiles, flooring and wallpaper are produced in batches (“dye lots”), and colour can shift slightly between them. Buying everything together — including the waste allowance — guarantees a consistent finish. Going back for “just one more box” often means a visible mismatch.

Keep the leftovers

After the job, keep a spare box or a few pieces. Flooring and tile lines are frequently discontinued, and a future repair will be invisible if you have matching material from the original batch. A little extra spent now is cheap insurance against an ugly patch later.

Calculators for this

• Tile Calculator — How many tiles you need for a floor or wall, with waste.
• Flooring Calculator — Boxes of laminate, vinyl or hardwood flooring to buy.
• Deck Board Calculator — How many deck boards for a deck of any size.
• Paver Calculator — Pavers plus base gravel and bedding sand for a patio.