Want to improve the look of your room? If you have a boarded floor, why not strip it back to the bare wood and seal it with a varnish, so the beauty of the wood grain shines through? The results look great, but it can be a dusty and noisy job. And as with so many home improvement projects, the quality of finish you achieve depends on the amount of effort you put into the preparation.
Tools & materials required
How to prepare your floor for sanding
Before you start sanding your floor, make sure the boards are in good condition, with no wide gaps or nails sticking out.
First, drive in any nails below the surface with a hammer and punch as if you leave any sticking out you'll tear your sanding sheet. Nail down loose boards and replace any damaged ones, ideally using boards of a similar age. You might even be able to take these from other rooms in your home where the floorboards aren't exposed.
Next, fill the gaps between the boards. If they're very wide, you might be better to lift and re-lay the boards more tightly, filling the final gap with an extra board. Otherwise, you can glue in narrow strips of wood.
Leave the filler strips slightly raised and let the glue dry. Then plane or sand them down until they're level with the surrounding boards. Finish the job by sweeping your floor clean.
How to sand floorboards
You'll need to hire a heavy-duty industrial drum sander and rotary edge sander to sand your floorboards properly. Make sure someone shows you how to change the abrasive sheets. As sanding creates a lot of dust, it's a good idea to seal doors to other parts of your house with masking tape and sweep up after each sanding session.
Top tip - Mind the gaps
Papier mache makes a good filler for gaps between floorboards. Mix a stiff paste with torn strips of newspaper (not coloured) and wallpaper adhesive. Colour this with a little water-based wood dye to match your sanded floor. Then force the papier mache into the gaps, smooth it off flush with the boards and let it dry before you start sanding.
Sanding a floor is a very dusty job. You must wear a dust mask and close-fitting eye protection. Keep the flexes of sanders out of the way by draping them over your shoulder, and plug them into a residual current device (RCD) to protect you from shocks if the flexes become damaged. Always unplug the sander before changing the abrasive sheet.
Start by fitting a coarse abrasive sheet to the drum sander, then work across your floor in overlapping diagonal strips. Sweep up the dust and repeat the process, working at right angles to your first sanding pass.
Every time you start or stop the machine, make sure you tilt the drum clear of the boards to stop it damaging them.
After you've levelled your boards by sanding diagonally, fit medium-grade paper to the drum and sand parallel to them, again overlapping each pass. Then finish it off with fine-grade paper in the same way. Try not to work across the grain of the boards as you'll leave visible marks.
The drum sander won't sand right up to the skirting - for this you'll need the rotary edge sander. Use coarse, medium and fine grades of abrasive paper and keep it moving, otherwise you'll end up with deep marks in your floor. And remember to tilt the machine as you start and stop the disc.
Finish the corners and inaccessible areas with abrasive paper wrapped around a sanding block or - much easier - a powered hand sander.
How to seal floorboards
You can use a clear or tinted varnish to seal sanded floorboards. Put on three coats to get a really hard-wearing finish and make sure your brush is completely clean before you start.
Top tip - Wire wool
Want to get a really clean, polished finish? Before applying your final coat of varnish, go over the dry floor lightly with some wire wool.
Sweep the sanded floor thoroughly and give it a good vacuum. After that, go over it with a lint-free cloth dampened with white spirit.
Thin the varnish for the first coat by adding 10% of white spirit to make it more workable. The first coat will seal the wood. Then, working towards the door, brush the varnish in the direction of the wood grain, checking that no pools form.
When the first coat has dried, remove any lumps or specks with fine abrasive paper and wipe clean with a lint-free cloth dampened with white spirit. Apply a second, unthinned coat and let this dry. Then put on your final coat.