A great deal of specialized equipment, planning, patience, and skill is involved with refinishing a hardwood floor. Of all the common home improvement tasks, this is one that requires research, time, and know-how, so it is only a do-it-yourself job for the very ambitious or thrifty. For weeks, you must go through several stages of evaluating, preparing, sanding, and sealing the floors, so there are many places where a small error could create a lasting problem.
It is entirely possible to refinish floors yourself, but many sources advise having assistance at certain stages. The first thing involved with refinishing a hardwood floor is determining whether your planks are good candidates for the arduous process. Assess whether floors have suffered damage from water, pet urine, or spills. Pull up one door's threshold to see if the boards are too thin to be sanded. Determine whether the last seal was varnish, wax, or polyurethane. Do your floors have deep gouges or dramatic wear patterns?
If most planks seem to have the same amount of seal, not too many scratches or holes, and are at least 3/4" (2 cm) thick, you have conquered the first step. Now, many days of preparation are involved in refinishing a hardwood floor. Thoroughly clean all surfaces. Fill holes from nails, staples, or scrapes. It's useful to get matching boards to replace damaged ones. Pull up all thresholds and possibly baseboards. You'll want to give all the floors in your home the same treatment, even if you only feel like one room is bad, just to keep them consistent.
Probably the most demanding step involved with refinishing a hardwood floor is the actual sanding. First, you need to rent a cumbersome, heavy, unfamiliar tool that looks like a lawnmower ate a miniature steamroller. This is a drum sander. It is incredibly loud, extraordinarily heavy, and so unwieldy that it may dissuade you from the project. By rolling it around the room in three passes, you are peeling off the top layer of finish, stain, and a good deal of wood to make the surface raw and flat.
If you survive the treacherous sanding (only a slight exaggeration), you still have to tackle staining and sealing. These are the last steps involved with refinishing a hardwood floor. You need to clean every speck of sawdust, so it doesn't contaminate the liquid applications. Stains are notoriously challenging to apply without streaks or demarcations. Over this, you apply a thin coat of polyurethane. This is the best kind of sealer to protect your floor from sunlight and shoes. You'll probably want several coats, with steel wool in-between. All told, refinishing a hardwood floor may take up to 1-3 weeks or more, not to mention several trips to the home improvement store.