Answer: When you drop an iron on one and need to make a claim. Ridiculous as it may seem flooring is only flooring if it goes wall to wall. Otherwise its a 'set' and the insurance company will only pay to replace the damaged tile and not the whole 'set'! Be warned this also goes for a set of a three piece suit or a set of a bathroom suite. So just check if your policy states that "the insurer will not pay the cost of replacing or repairing any undamaged parts of the buildings which form a pair,SET,suite or part of a common design or function when the loss or damage is restricted to a clearly definable area or to a specific part" Fortunately there is hope. After speaking with the Financial Ombudsman Service, who apparently deal with this type of situation regularly, they have come to a compromise and if you are unable to match or replace the item then you are entitled to receive 50% of the entire bill. The insurance company WILL be aware of this fact.