How to Sand and Varnish Floorboards

Written by samantha volz
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How to Sand and Varnish Floorboards
Old floorboards need considerable sanding and varnish to look their best again. (Jupiterimages/ Images)

The classic look of wooden floorboards appeals to many homeowners who want a rustic feel in the home. Over time, however, even finished floorboards begin to fade and break down under constant foot traffic, sunlight and moisture exposure. Renovating these floors involves sanding the surface to remove damage and old finish and applying a fresh coat of varnish. Despite the work involved it is generally still easier and less expensive than replacing the whole floor.

Skill level:

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Things you need

  • Broom or vacuum
  • Chalk
  • Scrap wood or plastic
  • Hammer
  • Wood filler
  • Putty knife
  • Floor sander with coarse, medium and fine sanding discs
  • Varnish
  • Paintbrush or roller

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  1. 1

    Remove all furniture and other objects from the room. Sweep or vacuum the floor to remove surface dirt and dust, allowing you full access to clean floorboards.

  2. 2

    Inspect the surface. Mark any holes or dips in the surface with chalk. Run a flat piece of wood or plastic over all nails holding the boards in place. If you find any that protrude from the surface, hammer them down completely. Protruding nails will tear apart the sandpaper used for renovations.

  3. 3

    Fill in any holes or dips in the floor with wood filler. Choose a filler that matches the colour of your floorboards as closely as possible. Mix the filler with hardener per product instructions and pack the filler into the hole with a putty knife. It's OK if you overfill a little, since you will sand it flat later. Allow any repair work to dry completely before continuing.

  4. 4

    Lock a coarse sandpaper sanding disc onto your floor sander. Follow specific product instructions, as every sander is different. Attach the bag that will catch the sanding dust and plug in the sander.

  5. 5

    Start in one corner of the room and work in 45 degree passes across the floor. Lift the sanding disk handle to hold the disc over the floor and activate the sander. Gently lower the disk to the floor and begin walking the sander in your desired direction. Do not linger in one spot too long, or you could damage the floor.

  6. 6

    Make a second pass at the floor, working at 45 degrees in the other direction across the floor. This angled sanding will level the floor, eliminating bumps and high points.

  7. 7

    Make two passes each with medium and fine sanding discs. After you finish with the coarse paper, you can work in straight lines along the floorboards, working with the length of the boards.

  8. 8

    Vacuum or sweep the floor after you are finished sanding to catch any dust that the bag may have let fly free. The floor must be completely clean before varnishing or the dust and dirt will show through the finish.

  9. 9

    Paint your chosen floor varnish onto the floor using a large paintbrush or roller. Work in thin coats only, spreading one thin coat onto the surface and allowing it to dry completely before applying a second. Follow specific product instructions regarding drying time and the number of coats to use, as every product is different.

Tips and warnings

  • Rent or purchase floor sanders, as well as the other materials needed for this project, at hardware and home improvement stores, as well as flooring speciality retailers.
  • Always unplug your floor sander when changing or replacing the sanding discs. This will prevent accidental injury.
  • If you have trouble getting to the boards that are right up against the wall or in corners, consider using an edging sander or detail sander. Both are hand held versions of the floor sander. These tools can be very heavy and can be hard on the back, so use only if necessary.
  • If boards are severely cracked, rotted or otherwise damaged, replace them. Do not attempt to simply cover up damage, as this can result in later floor failure and potential injury.
  • Wear ear protection and dust mask when sanding to avoid injury or breathing in harmful amounts of dust.

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