Hardwood floors typically last for the life of a home, but eventually they will need refinishing or refurbishing. Refinishing
If the floors are simply dirty from years of use but aren't worn through to bare wood, you can probably clean them with household detergent and elbow grease, or you can rent a floor-buffing machine with an abrasive pad. After all the dirt and wax is removed you can then apply a new finish coat.
Refurbishing
If your floors are in bad shape, you can often sand them back to their original state. If the floor is reasonably flat and free of dips and gouges, all you need to do is remove the finish with a vibrating sander. Vibrating sanders work on the same principle as handheld finishing sanders: The machine's flat pad with sandpaper vibrates and oscillates to remove the old finish.
Solid wood-strip floors can be sanded and refinished several times. Engineered wood floors, however, are made from laminated wood products and can be sanded only once and only with great care.
Tools and Materials
| Plastic sheeting | Hammer | Pry bar |
| Nail set | Putty knife | Large flooring sanders |
| Edge/random-orbit sander | Paint tray | Lamb's wool applicators (for varnish) |
| Clean rags | Paintbrush or foam brush | Dust mask/respirator |
| Shop vacuum | Tack cloth | 8d finishing nails |
| 220-grit sandpaper | Steel wool | Blue painter's masking tape |
| Latex wood putty | Wood stain | Varnish |
Before You Start
Preparation
- Before refinishing remove all the dirt and wax from the floor but not the finish itself.
- Make sure that the floor isn't too thin to sand. Pull up a floor vent or take off the threshold or the baseboard to reveal the edge of a floorboard. You can sand until you're just above the tongue and groove.
- Always exercise caution when using a sander for your floors. Vibrating floor models are bigger and heavier but easy to control.
- If you're not comfortable running the machine, call a professional to do the sanding, then do the finishing and staining yourself.
- Follow the manufacturer's instructions application of stains and finishes, as well as drying times.
- Refinishing or refurbishing a floor is a great do-it-yourself project that is considerably cheaper than buying a new floor or having one installed.
Step 1. Remove the shoe molding. A floor sander may bang against base molding, so remove it. Usually all you have to do is remove the shoe molding—the quarter round that runs along the floor. Pry it off as shown, protecting the baseboard with a piece of scrap wood. If there is no shoe molding, either remove the base molding or take care not to damage it with the sanders. 
Step 2. Fix squeaks and shore up the floor. Check for squeaks and nail loose floorboards. The best approach is to nail into a floor joist, not just the subfloor, with 8d finishing nails. Find protruding nails by sliding the blade of a putty knife across the floor. Set the nails and fill the holes with latex wood putty. 
Step 3. Contain the dust. To prevent dust from spreading throughout the house, close off doorways and ductwork with plastic sheeting. Stick strips of masking tape around the edges of closet doors. If possible, pull the dust out a window with a box fan. Wear a dust mask when sanding. 
Step 4. Rough-sand the floor. Ask your tool rental company what kind of sander to use when rough-sanding your floor. If the floor itself is in bad shape, start with a drum sander; if it just needs refinishing, use a vibrating sander (Step 6) instead. When drum sanding, start with the coarsest sandpaper grit—typically 36 or 40 grit—then switch to 60 grit. Finish with 80 or 100 grit. Move the sander along the length of the boards, with the grain. Work it back and forth over 3'-4' lengths, overlapping strokes by at least 1/3 the belt width. GOOD IDEA: Trial Run
A drum sander is difficult to maneuver until you get the hang of it. Ask the rental company for a demonstration and some operating tips, and practice on an old sheet of plywood before you start on your floor. Start with fine sandpaper, then switch to coarser grades when you’re more comfortable.
Step 5. Sweep and vacuum. Sweep and vacuum between sandings. The sanding dust eventually gets in the way of the sanding process and must be removed. Always sweep and vacuum before moving on to the next grit of sandpaper. Doing so not only cleans the floor, it also picks up any debris left by the sandpaper that would scratch the results of the finer-grit paper. 
Step 6. Fine-sand the floor. Fine-sand with a vibrating sander (optional). These sanders level minor unevenness left by drum sanders. If you use both tools, use the drum sander for the two coarse grits (36 and 60), then use the vibrating sander for the medium and fine grits (80 and 100). If you use only the vibrating sander, start with 60-grit, then sand with 80-grit and, finally, with 100-grit. 
Step 7. Sand the edges and corners. Sand corners and edges with an edge sander. The edge sander usually comes as part of the rental. Use 80-grit paper to reach areas that the large sanders fail to reach: in corners, under radiators, in small closets, etc. Edge sanders can be difficult to control; practice on a hidden area, such as the inside of a closet, until you get the hang of it. 
Step 8. Finish-sand the edges. A random-orbit sander is easier to control than an edge sander. Use it to finish tight places such as corners. Random-orbit sanders are less aggressive and less likely to gouge. They do an excellent job, at a slower pace. 
Step 9. Apply stain. Apply a wood stain (optional). When the sanding is done, vacuum up all the dust and follow up with a tack cloth. Apply wood stain with a foam applicator pad. Work one manageable area at a time—4 square feet, for example. Always stain in the direction of the wood grain. 
Step 10. Wipe off excess stain. Most manufacturers recommend removing excess stain as you go—usually a few minutes after you apply it. Use clean cotton cloths or paper towels. Some finishers prefer wiping the floor with a cotton cloth wrapped around a dry applicator pad. To keep a lamb’s-wool applicator from drying out overnight, store it in a tightly sealed plastic bag. When it’s time for the next coat, unwrap the applicator and you’re ready to go. SAFETY ALERT: Oil-Soaked Rags Are a Fire Hazard
The heat generated naturally from oily rags can set the rags on fire, especially if they are bunched together or in a closed container. Hang the rags outside, away from any structures, and allow them to dry thoroughly before disposing of them.
Step 11. Apply finish. Allow the stain to dry as recommended before applying the first coat of varnish. Polyurethane, either oil-base or water-base, is a reliable finish for floors. Apply the finish with a lamb’s-wool applicator. Sand the floor lightly with 220-grit paper or #000 steel wool. Vacuum up the dust. Apply three coats of oil-based finish or four coats of water-base finish, sanding in between.
