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Choosing a floor sander: which type suits your floor?
For a solid wood floor or floorboards that need sanding back to bare wood, use a drum floor sander with an edging sander for the borders. For engineered wood flooring or a light sand, a rotary floor sander is the safer choice because it removes less wood. Corners, stair treads and the spots under radiators are best done with a detail sander or by hand.
What will you learn in this article?
- What types of floor sander are there?
- Which floor sander suits your floor?
- How to prepare a floor for sanding
- Which grit should you use for sanding a floor?
- Step-by-step: how to sand a wooden floor
- Safety when sanding floors
- Common mistakes when sanding floors
- Frequently asked questions about floor sanders
- In short: choosing a floor sander
What types of floor sander are there?
| Type | How it works | Good for | Watch out for |
|---|---|---|---|
| Drum sander (drum or belt) | Rotating drum with a sanding belt | Sanding solid floors and floorboards back to bare wood, old varnish and adhesive residue | Removes a lot of wood, quickly leaves dips if you stand still |
| Rotary floor sander (disc) | Large round disc that runs flat over the floor | Engineered wood, sanding between coats, wet sanding floors | Slower on thick coatings |
| Edging sander | Small round disc that gets close to the wall | Borders along skirting boards, under radiators | Easily leaves swirl marks |
| Detail (delta) sander | Triangular pad | Corners the edging sander cannot reach | Only for small areas |
| Random orbit sander | Spins and oscillates at the same time | Small floors, stair treads, local repairs | Too slow for a whole room |
A drum sander and a large rotary floor sander are heavy, expensive machines that you would usually hire from a tool hire shop. For edges, corners, thresholds and stairs, having your own random orbit or detail sander is handy, for example a cordless model from the Maxxpack 18V range.
Which floor sander suits your floor?
Solid wood floor or pine floorboards
This is where a drum sander is the right tool. A solid floor has enough wood in it to be sanded several times. If the floorboards are very uneven, first sand diagonally (at roughly 45 degrees), then along the length of the boards.
Engineered wood flooring
Engineered wood has a top layer of real wood on a backing board. That top layer is often only a few millimetres thick, and a drum sander will go through it quickly. Use a rotary floor sander instead and remove as little as possible. Check the thickness of the top layer beforehand at a threshold strip or floor vent.
Laminate and vinyl
You cannot sand laminate or vinyl flooring. The surface is a printed image or a thin wear layer. If it is damaged, replace the individual boards. Our guide on how to install laminate flooring explains how the boards fit together.
How to prepare a floor for sanding
- Fix skirting boards firmly and tape them off, or remove them if you plan to replace them anyway.
- Remove carpet, staples, gripper rods and as much adhesive residue as you can with a scraper.
- Punch nails below the surface with a nail punch. A protruding nail tears the sanding belt and can damage the drum.
- Repair loose or broken boards.
- Clean the floor and make it dust-free.
- Lay a damp cloth along the gaps under doors and seal doorways with plastic sheeting.
- Has the floor just been laid and glued? Wait until the adhesive has fully cured before sanding. Check the adhesive packaging: this is often at least 24 hours, sometimes longer.
Which grit should you use for sanding a floor?
On floors you work in three or four passes, from coarse to fine:
- 24 to 40 grit: only for very old varnish, paint or uneven boards.
- 60 grit: the first pass on most floors.
- 80 to 100 grit: removing the scratches from the previous grit.
- 120 grit: the final pass before varnish or oil.
Never skip more than one grit. Use the same grit sequence on the edges as in the middle of the floor.
Step-by-step: how to sand a wooden floor
Start in the middle of the room
Begin with the drum sander or rotary floor sander in the middle of the room.
Never lower the drum while standing still
With a drum sander, never let the drum touch the floor while the machine is stationary. Get the machine moving first, then lower the drum onto the floor. Lift the drum before you stop.
Work in overlapping lanes
Work in lanes that overlap slightly, following the length of the boards.
Sand the edges
Then sand the edges with the edging sander, using the same grit.
Do the corners
Finish the corners with a detail sander or a scraper.
Vacuum and repeat
Vacuum thoroughly and repeat with the next grit.
Remove all dust
After the final pass, vacuum everything, including windowsills and skirting boards, and wipe the floor with a slightly damp cloth.
Apply the finish
Apply the varnish or oil according to the manufacturer's instructions.
Safety when sanding floors
- Wear at least an FFP2 dust mask, ear defenders and safety glasses. A drum sander is noisy and makes a lot of dust.
- Empty the dust bag after every pass and always at the end of the day. Fine sanding dust containing old varnish or oil residue can heat up and catch fire. Empty the bag outside into a metal bin or a sealed bag and keep it away from heat sources.
- Lay rags soaked in oil or stain flat outside to dry, or keep them in a sealed metal tin filled with water.
- Keep the cable behind you so you do not sand over it.
Common mistakes when sanding floors
- Letting the drum sander stand still with the drum on the floor. That leaves a dip instantly.
- Moving to a fine grit too quickly, so scratches are left behind.
- Using a different grit on the edges than in the middle, which causes colour differences after varnishing.
- Sanding engineered wood with a drum sander.
- Not removing all the dust before varnishing.
Frequently asked questions about floor sanders
Should I hire or buy a floor sander?
For a one-off job, hiring almost always makes more sense, because drum and rotary floor sanders are large and expensive. Ask the hire shop for the right sanding belts and discs too. Your own random orbit or detail sander is useful for edges, stairs and later maintenance.
How often can a wooden floor be sanded?
That depends on the thickness of the wear layer. A solid floor can often be sanded several times. Engineered wood with a thin top layer sometimes only once or twice. If in doubt, ask the supplier of the floor.
Can I sand a floor with a random orbit sander?
For a small space such as a toilet or landing, yes. For a living room it takes a very long time and the result will be less flat. Use the random orbit sander for the edges and repairs instead.
How do I avoid swirl marks along the edges?
Swirl marks usually come from the edging sander. Keep it flat, apply little pressure and keep it moving. After the final pass, lightly sand the edges again with a random orbit sander or by hand, with the grain.
In short: choosing a floor sander
Use a drum sander and an edging sander for solid wood floors, and a rotary floor sander for engineered wood. Work from 40 or 60 grit up to 120, never let the drum stand still on the floor and empty the dust bag regularly. Tackle corners, stairs and small areas with a detail or random orbit sander.
