Material and waste
Waste covers cuts, layout, damaged pieces, pattern matching and future repairs. It changes by material and does not automatically increase labor square footage.
Installation and demolition
Installation method, occupied spaces, stairs and demolition difficulty can change labor. Glued flooring and tile removal typically require more effort than floating floor removal.
Subfloor and moisture
Flatness, damage and moisture may not be visible before demolition. A calculator can include an allowance, but an inspection at the property is essential.