Last Updated Mar 7, 2017 · Written by Rob Schneider
Sanding timber floors is arguably a job you should leave to floor sanding specialists. If you want to try DIY floor sanding, make sure you know what you are doing or you could end up ruining your floor. These five tips for floor sanding cover the most important things to do if you want a flawless floor.
You will need at least two sanding machines: a large belt sander for the bulk of the sanding and an edge sander for the areas close to your skirting boards. You can find them at most equipment hire shops, but don't settle for the cheapest belt sander you can find. Look for a relatively new, good quality belt sander. A floor sander is a heavy piece of equipment designed to quickly sand the floor. If it's not in good condition or you don't use it properly, it can damage your floor.
Your equipment hire shop will also sell you belts and discs for your sanders. You will need several grits. In most cases, you will start with 40 grit and use increasingly finer grits to get a smooth finish after you have removed the old finish from the floor.
Before you begin sanding, you need to remove all the furniture from the room. You will produce quite a bit of dust while you're sanding, so also remove curtains, blinds and anything else that needs protection from the dust.
Take a close look at your entire floor. If you find any nails, countersink them. You don't want to sand nails or have a protruding nail rip your sandpaper.
If your floor is old, it's a good idea to find out how much timber you have left to work with. Timber floors are made from "tongue and groove" floorboards. If your floors have been sanded and finished several times, there may be only a small bit of "tongue" at the top of the floor. You could sand through the tongue and end up with an ugly repair job or be unable to repair the floorboards. Check before you sand and you'll know if it's safe to sand your floors.
Belt sanding is the most critical part of the floor sanding process. It is a three-stage process. Between each stage, you will need to do your edge sanding with increasingly finer grits of sandpaper.
Before you turn on your belt sander, you need to tilt it back so the sander doesn't start rolling across the floor. Then slowly lower it to the floor. If you drop it quickly, you risk gouging the floor or leaving chatter marks. When you start sanding, move at a steady pace to sand the floor evenly. The three stages of belt sanding are:
Vacuum the floor between each sanding and then use your edge sander near the skirting boards. Vacuum again and inspect the floor. If anything needs putty, fill it and let the putty set before you sand again.
You will need to edge sand between belt sandings. Use the same grits you use with your belt sander. You may also need to buy or hire a "V" shaped sander to get into the corners and other awkward areas. When edge sanding, overlap the edges of the area you've sanded with your belt sander about 100-150mm. Don't sand the middle of the floor. If you do, it will leave swirl marks that will be noticeable after you polish the floor and may leave a depression in the timber. Be careful to keep your edge sander level. If you tip it, it can gouge the timber.
If you want to use a natural oil finish, you should buff the floor before you apply a finish. The buffer is a separate machine you should be able to find at your equipment hire shop. Use a 100 grit screen back (the buffer) and work at a steady pace, starting in the middle of the floor. Pay particular attention to the areas where you have overlapped the belt sander and the edge sander.
If you will be using a synthetic sealer/polish, you may not need to buff it first. In either case, you need to make sure the floor is dust-free before you apply the finish. Be careful when vacuuming. If you drag the vacuum across the floor, it will leave marks that will show up through the finish. Vacuum with the grain to remove the dust and also vacuum window sills and other areas where dust might fall on to your wet finish.
If you've never sanded a floor before, start with a floor that will be covered by a bed or a rug. This way, you get a chance to practice your technique first. If you make a mistake, you may be able to cover it. If you are only sanding a large floor and want to be sure to get a flawless finish, get quotes from floor sanding services first. It may be worth paying extra for their professional services.