Your Step-By-Step Guide To Sanding A Hardwood Floor

Sanding your hardwood floors isn't the most difficult thing you're going to do for your house, but it is a professional skill that requires you to not only do the steps right, but also to do the right steps. We spoke exclusively with Bob Beacham, House Digest's expert carpenter and remodeler, about how to nail down the step-by-step process for floor sanding. Beacham laid it out simply for us — but he did warn that there are reasons to avoid DIY hardwood floor sanding.

"Anyone with reduced mobility/physicality might struggle with this kind of work," Beacham said. "If you aren't confident, it's better to call a pro." Renting the necessary equipment can be expensive, and Beacham says the difference might be smaller than you think. "Reputable contractors will often offer a free quote so you can get professional advice before you decide how to proceed," he said. Part of that free consultation should be evaluating whether your floor can handle the sanding and refinishing process, and whether it will even work.

Once you're confident that DIY floor sanding is the right path for you, it's time to prep your work area. "Clear the room," Beacham said. Completely emptying the room is a key preparation step. "Cover anything that can't be removed with plastic sheeting. Tape up the edges. Cover and tape up windows and doors. Sanding dust will get into adjacent rooms if you don't. That stuff gets everywhere. Remove moldings to make it easier to get to the edges of the room." You should also make a point of carefully scanning for nails, and driving them below the surface before you sand. 

You will, of course, need to rent and buy the floor-refinishing gear you'll need from an outlet like Home Depot. You'll need to buy consumable supplies like sandpaper, of course, and gear like personal protective equipment. When House Digest spoke with remodeling expert Bob Beacham exclusively, he recommended either an N95 lightweight disposable dust mask like the 3M Particulate Respirator or a half-mask respirator like the 3M Half Facepiece Reusable Respirator. You should also consider additional woodworking safety precautions like goggles and hearing protection.

You will probably want to rent the heavy-duty sanders you'll need: a belt sander, random orbital sander, and edge sander. Beacham said that sometimes upright rotary sanders (which are not the same thing as random orbital sanders) are used for the rough sanding done in the first phase. Rotary sanders are sometimes called rotary buffers.

Beacham says that one common mistake is to try refinishing a floor with hand sanders. "They're too small," Beacham said. "They will take forever and, worse, are likely to make the floor uneven. Hire pro equipment." You will, however, probably be able to use a hand-held detail sander in corners and out-of-the-way spots like stairs and closets. A detail sander like the Skil Corded Multi-Function Detail Sander is useful for sanding in corners and other tight spaces, Beacham said.

Your next goal is to strip and level the floor with 35 to 40 grit drum sanding, but there's an important step to take care of first. While nearly every expert will tell you to start drum sanding your floor with a coarse grit, then move on to a finer one, when House Digest spoke exclusively with remodeling expert Bob Beacham, he had a better idea. "Some of these machines can be quite aggressive and take a while to get used to," he said. "You might want to try a patch with 50 to 60 grit first to acclimate yourself."

Sand the room in the grain direction using the drum sander, then use an edge sander to take care of areas that are too small or too near a wall to use the drum sander on. You should generally match the grit of the edger with the grit you're using on your big upright sander during any given step. This is the one opportunity to make use of that handheld detail sander you might have considered using on the whole floor. After all the sanding, vacuum the floor thoroughly.

Now it's time to repeat the sanding process, but with a finer grit. "After going over the floor with the coarse grit, hoover up any dust and debris (like grit particles that fall off the sandpaper), then move onto the medium grit (50 to 60)," Beacham said. "This will remove scratches left by the coarser grit. Hoover again."

Next, you'll replace the drum sander with the random orbital sander. "When the floor looks smooth and is free of marks, use a large random orbital sander for finish sanding at 80 to 100 grit, or even 120 grit if you want a high-shine finish," House Digest's in-house remodeling expert Bob Beacham told us exclusively. "The purpose is to remove any scratches left by the medium grit. Random orbitals take longer but are better at doing this than belt sanders. Hoover again before applying stain or varnish."

You'll repeat the full process with whichever grit you choose: First, sand the bulk of the floor with the random orbital sander. Then, take care of any areas it won't reach with the edge sander and detail sander. The key, Beacham said, is to take your time and do each step thoroughly, including the final vacuuming. "Be patient. Don't try to rush the job. Clean thoroughly after each step," he said. "After the last sanding and hoovering, don't apply finish straight away. Leave the floor overnight, then hoover again. It's surprising how much airborne dust will have settled out — and would otherwise have settled into your chosen finish."

It's common to hurry and take shortcuts, but Beacham warns that the final step of the job — finishing the floor with stain or varnish — will magnify any lingering sanding marks as you progress through higher sanding grits. "Take your time," Beacham reiterated. "Be thorough." It's great advice for any DIY job, and indispensable for floor refinishing. Beacham has offered some other expert tips to know before refinishing wood floors, as well.