Normal Wear
Normal wear and tear occurs naturally, from "normal" use of a home the tenant cleans and maintains properly. There's no definition of what constitutes "normal" wear of flooring unless your lease defines the term; however, landlords generally overlook light scratches in wood flooring, carpeting that's matted or slightly worn in high-traffic areas, and indentations or crushed pile from furniture. If your bathrooms and/or kitchen have tile flooring, the landlord might consider some cracking of the tiles and the grout to be normal wear. None of these conditions should cause you to lose security money.
Damage
Negligence, accidents and other special situations that cause damage to flooring generally are, in fact, damage rather than normal wear. Damage includes cracked tile from dropping a heavy pot, carpet stains and tears, gouged wood or vinyl that requires repair, burns, water stains from unreported leaks, excessive dirt and a build-up of mold and mildew. Your landlord is within his rights to deduct from your security deposit the costs of cleaning or repairing these conditions.
Minimize Damage
Make a careful note of the condition of your floors before you move out of your home. Clean hard surfaces with a cleaner that's safe and appropriate for the flooring material. Treat carpet stains with a pre-treatment solution, and steam clean the carpets with a commercial-quality machine available at many supermarkets and rental centers. Don't attempt to sand or refinish wood flooring yourself. If you believe you can have the work done for less money than the landlord is likely to withhold from your security, ask permission to hire a professional to do the job.
Next Time, a Walk-Through
Request a walk-through of your next home just prior to your move-in date so that you can identify damage to the home's floors and report them to the landlord. Use a checklist that includes each room in the home and such items as windows, walls, ceilings, light fixtures and doors, in addition to the flooring. Take photos of the issues you report to further reduce the likelihood of future misunderstandings. Keep track of measures you take throughout the term of your lease to protect and repair your flooring. For example, save steam-cleaning receipts and record the date you re-grout a bathroom floor.