A tired hardwood floor usually needs less work than people expect. Before you rent a drum sander, figure out whether the damage is in the finish or in the wood, because that one answer decides the whole job.
We’re a flooring installer in Glenview, and this is the advice we’d give a neighbor who wants to try it themselves.
Screen and Recoat or Full Sand
There are two ways to restore a finished hardwood floor.
- Screen and recoat. Also called a maintenance coat, this scuffs up the existing finish and adds a fresh coat on top. It never touches bare wood.
- Full sand and refinish. This takes the floor down to raw wood, then you stain if you want and apply new finish. It removes damage, and it removes wood.
A recoat fixes dull, lightly scuffed floors. A full sand is for deep scratches, dents, worn paths where the finish is gone and a color you want to change.
Diagnose the Floor First
The Fingernail Test
Run a fingernail across the worst scratches. If your nail catches, a recoat won’t hide it.
A Wood Floor Business article on recoating puts it plainly. Any scratch you can feel with a fingernail will still be there after recoating.
Look for Bare Wood
Check the traffic paths, the area in front of the sink and inside each doorway. If the finish has worn through and the wood looks gray or dirty, you’re past a recoat. The NWFA recommends a full sand once bare wood is showing.
Check for Wax, Polish and Factory Finishes
New finish won’t bond to wax, many store-bought polishes or some factory finishes. Hardwood Floors magazine suggests a few simple checks.
- Wax. Wipe a spot with mineral spirits on a white rag. A yellow or brown tint suggests paste wax.
- Acrylic polish. Dab ammonia on an out-of-the-way spot. Milky white spots after about two minutes suggest a polish that has to be removed first.
- Nonstick factory finish. Mark a hidden spot with permanent marker. If the ink wipes right off, the finish likely contains Teflon, and the magazine says those factory finishes can’t be recoated.
Test in a main room, not a closet. Closets rarely see the cleaners that cause trouble.
Know What Kind of Floor You Have
If your floor is engineered, find out how thick the top layer is before any sanding. Pull a floor register or look at a cut edge at a threshold.
A full sanding removes about 1/32 to 1/16 inch of wood, and Hardwood Floors magazine advises against sanding a wear layer thinner than 3/32 inch. A thin wear layer leaves no room for mistakes.
How to Screen and Recoat
- Clean the floor thoroughly with a cleaner the finish manufacturer approves, including the edges and the gaps between boards.
- Do a test spot in a worn, high-traffic area. Once it cures, score a small X through the test coat, press tape over it and pull it off fast. If finish lifts with the tape, stop.
- Abrade the whole floor lightly with a buffer and a screen or abrasive pad, always with the grain.
- Vacuum, then go over the floor with a tack cloth. A single hair or speck of dust will show through the finish.
- Apply one thin, even coat and keep everyone off it until the label says it’s ready.
Floors with tough factory finishes may need a chemical bonding product from the finish maker instead of, or along with, the screening step. Use that manufacturer’s complete system and don’t cut corners on its dry times.
How to Do a Full Sand
A full sand is a much bigger job. Expect several days, a lot of dust and a real learning curve.
- Rent a drum or belt sander and an edger, and ask the rental shop for a demonstration. Practice on a sheet of scrap plywood before you touch the floor.
- Work up through the grits, roughly 40, then 60 to 80, then 100. Sand the edges with each grit before moving to the next one.
- Keep the machine moving and let its weight do the work. Pressing down or pausing in one spot leaves divots.
- Fill holes with wood filler, let it dry and sand those spots again.
- Vacuum and tack between every step, and turn off the furnace or air conditioning while you sand so the dust doesn’t circulate.
Finish choice comes next. Water-based finishes dry fast, smell less and stay clear. Oil-based finishes dry slower, which gives a beginner more time to work, but they’re amber in color and give off stronger fumes, so wear a respirator.
Staining raises the stakes. Stain highlights every sanding mark, and maple and birch are much harder to stain evenly than oak.
What DIYers Get Wrong
- Recoating a floor that needed a full sand, or sanding a floor that only needed a recoat.
- Skipping the adhesion test and finding out a week later that the new coat peels.
- Leaving drum marks, gouges or a shadow along the baseboards from tipping the edger. Fixing those takes even more wood off the floor.
- Sanding away the beveled edges on a prefinished floor, which removes a lot of material.
- Rushing dry times between coats.
- Piling up oily rags. Rags soaked with oil-based stain or finish can heat up and catch fire as they dry, as a National Fire Protection Association engineer explained to Consumer Reports. Its advice is to spread them outdoors on the ground or a metal rack until they’re completely dry and somewhat hard.
When to Call a Pro
A refinishing contractor is worth the money if any of these apply.
- The floor is engineered and you can’t confirm the wear layer is thick enough.
- Boards are cupped. Hardwood Floors magazine notes a cupped floor stays cupped after a recoat, and sanding it before the moisture problem is fixed can create new trouble.
- There are deep pet or water stains, which often go deeper than sanding can reach.
- It’s a large open floor plan where an uneven result would show from room to room.
- A previous sanding already took a lot of wood off.
For comparison, This Old House’s 2026 cost guide puts professional sanding and refinishing at about $3 to $8 per square foot. Weigh that against the rental, the supplies and several days of your time.
If the boards are too far gone, or you’re ready for a different floor anyway, our hardwood flooring installation page covers that route. And once your floor looks good again, our guide on how to maintain your hardwood floors will help keep it that way.