If your solid hardwood floor has major problems, such as deep discoloration, protrusions, or grooves and pits, the only way to restore the floor to its original glory is by sanding. It's a job best done with a specialty floor sander. There are several types of floor sanders available, but the one that does the job the fastest is the upright drum sander, a large walk-behind power tool that is readily available to lease at major home centers and tool rental outlets. DIY floor sanding with a drum sander is entirely possible for a DIYer with moderate skills and stamina, but keep in mind that this is a large, powerful tool that can easily damage a floor unless you understand how to use it correctly.
Before You Begin
Before making the decision to sand your hardwood floors yourself, take some time to evaluate your floors, and learn about the tools and materials required.
Sanding a solid hardwood floor makes sense when the floor surface still looks shabby after simple stripping and revarnishing. Shallow stains and scratches can often be erased almost completely by sanding the floor. But be aware that most solid hardwood floors can tolerate only two or three sandings over their lifetime before you risk sanding down into the tongue-and-groove joints.
And be aware that many hardwood floors are not solid wood, but are instead veneered products comprised of a relatively thin solid hardwood layer bonded to a core of composite wood or plywood. These types of floors may still be sandable, but usually only once over their lifetime.
One good way to evaluate your hardwood floor is to look for a spot where the edge of the flooring is exposed, such as by removing an HVAC floor register. If you look at the flooring layer along its edge, you will be able to see if it is solid hardwood or a veneer product, and verify that there is enough hardwood to tolerate a sanding that will remove as much as 1/16 inch of wood.
Floor sanders come in three distinct types: upright drum sanders, upright orbital sanders, and edge sanders.
- Professionals typically use a large upright drum sander to sand down the bulk of the floor area. The drum sander works by rotating a wide sandpaper sleeve around a cylindrical rotating drum. It can easily sand down hardwood, but it is a powerful tool that has the potential for badly damaging a floor. If the tool is tilted ever-so-slightly, or if the drum is allowed to grind away at a single spot, the floor can be damaged in a way that is very hard to fix. But there is no reason why a DIYer who works carefully cannot use a drum sander, as described below.
- Some homeowners find it easier to use an upright orbital sander for DIY floor sanding. This tool is also an upright, walk-behind tool, but it works by moving a large piece of flat sandpaper in small random orbits against the floor. Sanding with an orbital floor sander can take a little longer than with a drum sander, but the chances of damaging the floor are reduced. The techniques are quite similar to those described here for drum sanding.
- An edge sander is essentially a powerful, super-sized orbital hand sander that allows you to sand next to baseboards and walls. After using the drum sander, you will need to use this tool to complete the job.
- An under-radiator sander is a specialty tool with an extended flat sanding pad that is narrow enough to fit under iron radiators and other obstructions.
None of these floor sanders are tools that a homeowner needs to buy. They are all available for lease at major home centers and tool rental outlets. They are typically leased in four-hour or full-day increments. Tool rental costs will comprise the biggest expense for this project. Plan to spend around $100 to rent an upright drum sander for a day (half-day rental is also available). Rental fees for edge sanders are typically about half the cost of drum sanders. Sanding sleeves will cost extra.
Sandpaper for Floor Sanding
Like other types of sandpaper, the abrasive sleeves for drum sanders are available in different coarseness levels. For initial rough sanding of floors in bad shape, 40- or 60-grit sleeves are typically used. This is followed by a second sanding with a 100-grit sleeve, and a final pass with a 120- grit sleeve.
At the time of rental, purchase a range of sandpaper grits—more than you think you need. Most rental yards will buy back unused and clean sanding sleeves with the understanding that users need to buy more than what is needed. The reason that you want to buy a copious amount of sandpaper is that you do not want to be caught short of sandpaper while your drum floor sander is on the rental "clock." Running down to the rental yard or home center for more sandpaper cuts into your expensive rental time.
Ask a rental employee to put on your first piece of sandpaper. Most homeowners are unfamiliar with putting sandpaper on a drum sander, so it helps to watch someone else do it first.
Drum floor sanders are unwieldy monsters that weigh over 100 pounds. You will absolutely need help from a friend or rental yard employee to lift the sander onto your truck bed or into the back of your SUV. Remember, too, that you will need help with the sander when you get home.
When you do get it home and begin using the sander, avoid using extension cords if possible. If you must use one, choose a heavy-gauge extension cord according to the manufacturer's instructions. The motor on the drum floor sander draws so much power that it is possible to melt an improperly sized extension cord, resulting in an electrical fire.
When changing sanding sleeves, ALWAYS unplug the tool first. It's all too easy for the tool's trigger or switch to be accidentally activated while you are changing sandpaper.
Equipment / Tools
- Nail set and hammer (if needed)
- Small pry bar (if needed)
- Shop vacuum
- Drum sander (rental tool)
- Dust mask
- Hearing protection
- Safety goggles
- Sanding sleeves (40- or 60-grit, 100-grit, 120-grit)
- Sheet plastic
Inspect the Floor
Carefully inspect the entire floor surface, looking for loose or damaged boards, and nail heads that are exposed. If you can feel nail heads with your hand, countersink them using a nail set and hammer.
Loose boards should be carefully nailed down before beginning the sanding project. If board replacements are necessary, do this now. Sanding new boards along with adjoining old boards will help blend the repair area.
Remove Shoe Molding (If Needed)
If your baseboard trim work includes shoe molding at the junction of floor and baseboard, carefully remove this molding, using a small pry bar. Removing the shoe molding will allow you to sand right up to the baseboard, leaving a sleek, professional look after you replace the molding after refinishing the floors.
Clean the Floor, Prepare the Room
Thoroughly sweep, then vacuum the floor to remove all dust and debris. Follow this up by mopping with a barely damp cloth.
Although drum sanders have dust-collection bags, a considerably amount of dust will be raised. Block off HVAC vents and doorways with plastic, and open windows to help ventilate the space. You may also want to cover electrical outlets with tape to prevent dust from infiltrating the slots.
Wear Safety Gear
Wear a good respirator mask and safety glasses when using a drum sander. Even though the drum sander has a dust bag, the bag only collects the majority of dust, not all of it. And safety glasses are a must—drum sanders create sparks when they hit nails and are capable of shooting particles.
Install the Sanding Sleeve
The first pass of the sander is typically done with 40- or 60-grit sanding sleeve. Lift the front cover of the sander and slide the sleeve onto the drum roller. Close the cover.
Practice Moving the Sander
With the tool turned off, position the sander in the middle of the floor, oriented in the same direction as the flooring boards. When running the sander, you will be raising and lowering the sanding drum onto the floor as you begin and end each pass. How you do this depends on the type of sander you have rented. With some sanders, the drum is lifted from the floor by tilting it backward so it pivots up against the rear wheels. With other types of drum sanders, there is a lever on the handle that raises the entire body of the sander up off the floor and lowers it back down to engage the sanding drum to the floor.
With the tool turned off, practice raising the sanding drum by whatever method is appropriate for your sander, moving it to different positions on the floor, then lowering the drum back onto the floor.
Make the First Sanding Pass
- With tool turned off, wheel the sander to a position near one side wall, midway between the end walls, oriented in the same direction as the flooring boards. With the drum lifted off the floor, turn on the sander, then carefully lower the drum onto the floor while firmly holding the handle.
- Immediately allow the tool to "walk" slowly forward as you follow it toward the far end wall. Don't allow the drum to grind against the floor as you hold it motionless, as this can damage the floor by leaving a drum mark.
- As you approach the far wall, raise the sanding drum before the tool reaches the wall. Avoid hitting the walls, and don't try to get too close to the baseboards; these areas will be sanded later with an edging sander.
- Now, you will pull the tool backward along the same path to complete the sanding pass over the same section of floor. As you begin to walk backward, lower the moving drum onto the floor. Again, lift the drum as you reach spot where you started. Each sanding pass will consist of this same pattern: forward, then backward over the same strip of flooring.
With the sanding drum raised and the motor still running, reposition the sander about 4 inches to the side, then repeat the same forward-and-backward action to make the next pass. It is critical that the sanding passes overlap to ensure a smooth surface.
Continue in this fashion until the room is covered. You can then reverse the direction of the tool to sand any remaining floor area that was behind you during the first phase.
Most sanding sleeves will sand 100 to 400 square feet before they need to be changed. When you notice that the sander is no longer quickly removing the old finish, then it's time to change the sleeve.
Change Sanding Sleeve, Sand Again
Change the sanding sleeve to a medium-grit (100-grit), then complete the room again, following the preceding steps.
Perform the Final Sanding
Conclude by changing the sanding sleeve to fine-grit (120-grit), then make a third pass of the entire room.
With the drum sanding phase now complete, you can finish the edges and corners of the room with the edging sander.
Make sure to clean the entire floor before moving on to applying your chosen finish.
How Often to Sand a Hardwood Floor
This kind of major sanding can be done two or three times over the lifespan of a solid hardwood floor, but it may be possible only once if you have hardwood veneer flooring. Thus, drum sanding should be reserved for floors in serious need of refreshing. It is very often done when old carpeting is removed to expose a hardwood floor that was previously covered. It is also an excellent project to prepare a home for real estate showings.
When to Call a Professional
Sanding a floor yourself is a tricky operation requiring specialty tools. While floor sanders are readily available for rental, floor sanding requires careful technique, and it's quite easy to badly damage a floor if you hurry the work. Further, sanding a floor requires wrangling heavy power tools and some amount of time on hands and knees. It is hard physical work that's not for everyone.
Professional floor sanding services are widely available, and they usually offer a full range of floor finishing services, including staining and varnishing. If you find yourself questioning your ability or eagerness to tackle this job yourself, consider hiring a professional to sand and refinish your floor. Nationally, complete floor refinishing typically costs $3 to $8 per square foot.
Wood Floors. Cool Springs Press, 2017
Wood Floors. Cool Springs Press, 2017.
How Much Does it Cost to Refinish Hardwood Floors? HomeAdvisor.