Should I Order Extra Tile Beyond the Waste Percentage for Future Repairs?

The waste percentage in a tile order exists to absorb cuts, breakage, and layout adjustments that happen while the installer is working: edge pieces around a doorway, a tile that snaps wrong on the wet saw, a corner that needs a sliver cut. That figure runs about 10% for a straight-set layout and climbs to about 15% for diagonal, herringbone, or large-format patterns, according to the Tile Council of North America installation guidelines, and it's designed to be used up by the end of the job.

Repairs happen after the job is finished — a dropped skillet cracks a floor tile, a plumber has to pull three pieces to get at a shutoff valve, a shower tile debonds and needs to come out. If the only tile in the house is what's left over from waste, there's usually nothing left, because a competent installer uses most of that allowance on cuts. Treating waste and repair stock as the same pot is the single most common reason homeowners end up short two years later.

The fix is to keep them as two line items on the order: waste percentage for the install, and a separate attic-stock percentage that gets boxed up, labeled with the lot number, and stored untouched.

The National Tile Contractors Association Reference Manual points to roughly 5% of the total tiled area as a reasonable attic-stock allowance on top of installation waste — enough to replace a handful of cracked or stained tiles without opening a new box mid-repair. On a 100 sq ft floor that's an extra 5 sq ft, which combined with 10% waste brings the total order to about 115 sq ft, or roughly 12 boxes at 10 sq ft per box after rounding up.

That 5% baseline moves depending on a few conditions. Natural stone and handmade or artisan ceramic tile show more shade and texture variation between batches, so contractors often push attic stock toward the high end of that range on those materials. A tile that's part of a manufacturer's core, ongoing collection is lower risk — reordering later is realistic — while a closeout, imported, or limited-run tile should get extra stock now, because there may be no way to match it once the current pallet sells out. Phased projects matter too: if the kitchen floor goes in this year and a mudroom using the same tile is planned for next year, buying both phases from the same production run avoids a dye-lot mismatch that no amount of waste-percentage math will fix later.

Run the specific numbers for a room through the /tile-estimator or /floor-tile-calculator before ordering — plugging in the actual dimensions and tile size gives a box count that already separates the waste line from the attic-stock line, rather than leaving that math to be done by hand at the tile counter.

The most common failure isn't running out of tile — it's running out of the same tile. Glazed ceramic and porcelain are manufactured in dye lots, and even the identical SKU ordered eight months later can show a visible shift in shade or sheen under raking light. A patched-in tile from a different lot reads as a bright or dull square in an otherwise even floor, and there's no way to blend it after the fact.

Discontinuation compounds the problem. Manufacturers rotate collections, and a pattern that's in stock at order time can be pulled from the line before a repair is ever needed, leaving a homeowner searching discount lots or resigning themselves to replacing an entire wall or floor to fix one cracked tile. Attic stock sidesteps both problems for the cost of a few extra tiles bought once, while sourcing replacements later can mean a second delivery fee, a second site visit from an installer, and in the worst case a full re-tile.

On very small jobs — a single niche, a half-bath floor — the math can round down to nothing, which is why it's worth flagging a floor: keep at least 1 full box aside even when 5% of the area comes out to less than a box's worth of tile. A whole box is easier to store, easier to find in two years, and covers more repair scenarios than a handful of loose pieces would.