Prefinished hardwood flooring comes with a factory-installed polyurethane coating that is very hard and durable. Warranties for prefinished wood floors may extend as long as 100 years, attesting to the wood's durability; consult your warranty before refinishing a floor. However, if the finish has worn down to bare wood and the warranty has expired, it's time to consider refinishing.
Two problems crop up when refinishing a prefinished floor. First, the factory-installed polyurethane coating probably has not worn off on all areas of the floor but must be removed prior to refinishing. Sanding this coating off takes a lot of work, creating a lot of dust. Second, floors must be at least 3/4-inch thick to refinish, otherwise you risk sanding down to the sub-floor. Many prefinished floors are only 1/4-inch thick. Prefinished floors cannot be refinished as many times as plank floors, which are sanded and stained in the home.
Your best bet is to hire a professional before sanding and staining a prefinished floor. A professional floor installer is familiar with each manufacturer's recommendations for refinishing and has the experience to sand thinner floors without causing damage. A professional can also remove and replace any warped or marred pieces of wood.
It's possible that your floor doesn't need refinishing. Here's how to tell: Apply a few drops of water to the floor. If the water beads up or soaks in slowly, minor maintenance will suffice. If the water soaks in immediately, the floor has no protective coating and must be refinished.
The simplest approach is to polish wood floors with a polish or restoring finish, available at home improvement or hardware stores. These products are urethane or acrylic, and they coat the floor with a hard seal, which adds shine, protects the wood and fills in minor scratches and cracks. Select brands made by wood floor manufacturers. The next option is to screen the wood floor, which involves removing the top coat of polyurethane with a commercial floor screening and polishing machine, and applying new sealer. You can rent floor screening and polishing machines at a home improvement store. Consider screening if the surface coat is worn, dull or scratched but the wood underneath remains intact. Screening is much less expensive than sanding and staining, and it is easy enough that many homeowners tackle the project themselves.