Sand and varnish floorboards — HomeGraft

Sand old floorboards back to bare wood in three passes, then seal with varnish for a hard-wearing, natural-look floor.

SF-01Clear the room and strip it backRemove all furniture, rugs and curtains. Take up any carpet gripper rods and staples with pliers. Open windows for ventilation and tape plastic sheeting over the door gap to stop dust spreading to the rest of the house.

2 each · Dust sheets

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1 roll · Masking tape

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4 m · Heavy-duty plastic sheeting

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SF-02Punch down nails and screw down loose boardsWalk the whole floor and press down on each board. Any that move need fixing to the joist below with a 40mm countersunk wood screw, pilot-drilled first so the board doesn't split. Sunk nail heads must be punched at least 3mm below the surface with a nail punch, or the sander belt will rip on them.

RULES

20 each · Wood screws 40mm

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1 each · Nail punch

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KNOW THE RULES

Cables and pipes can run under floorboards almost anywhere, including along joists near sockets and radiators. Use a cable/pipe detector before drilling, but still treat every screw position as if something could be there. Find your stopcock (usually under the kitchen sink) and check it turns before you start, so you can shut off water fast if you hit a pipe. If a board is near a socket, light fitting or radiator pipe run and you're not sure what's underneath, isolate the circuit at the consumer unit or turn off the water at the stopcock before you drill.

SF-03Fill wide gapsIf gaps between boards are wider than about 5mm, fill them with a flexible wood filler or thin fillet strips glued in and planed flush once dry. Skip this step if gaps are small — trying to fill hairline gaps is a waste of time and the filler will just fall out.

1 tube · Flexible wood filler

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SF-04Hire and set up the sandersHire a drum or belt floor sander plus a separate edging sander from a tool hire shop — book both for the same day. Fit an FFP3 dust mask, safety glasses and ear defenders before switching anything on, and keep the room ventilated throughout. Attach the sander's dust bag correctly and empty it often; a full bag is a fire risk with fine wood dust.

1 day · Floor sander hire (day)

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1 day · Edging sander hire (day)

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3 each · FFP3 dust masks

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1 each · Safety glasses

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1 each · Ear defenders

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SF-05First pass: coarse grit, diagonalFit a 36-40 grit belt and run the sander diagonally across the boards in one direction, then diagonally the other way for badly worn floors. Keep the sander moving at all times — stopping while it's running will gouge the wood. This pass removes old finish and levels the surface, so don't rush it.

1 pack · Sanding belts, 40 grit (pack of 10)

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SF-06Second pass: medium grit, with the grainFit a 60-80 grit belt and sand along the length of the boards this time, following the grain. This removes the diagonal scratches from the first pass. Vacuum the floor before switching grits so leftover coarse dust doesn't scratch the finer belt.

1 pack · Sanding belts, 60-80 grit (pack of 10)

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SF-07Final pass: fine grit, plus edges and cornersFit a 100-120 grit belt for the last pass with the drum sander, again with the grain. Switch to the edging sander with matching fine grit discs to do the strip around the skirting and into corners the drum sander can't reach. Hand-sand any tight corners the edging sander misses using a sanding block.

1 pack · Sanding belts, 100-120 grit (pack of 10)

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1 pack · Edging sander discs, fine grit (pack)

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1 each · Sanding block

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SF-08Vacuum and tack the whole floorVacuum thoroughly, including skirting boards, window sills and any ledges where dust has settled — airborne dust will land back on the floor if you don't clear the room properly. Follow with a tack cloth or a barely damp microfibre cloth to lift the last fine dust before varnishing. Any dust left behind will show as grit under the finish.

1 pack · Tack cloths (pack)

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SF-09Apply the first coat of varnishUse a good quality floor varnish (oil-based for a warmer tone and toughest finish, water-based for faster drying and less smell). Apply thinly with a brush or roller along the grain, working away from the door so you don't trap yourself in the room. Leave to dry for the time stated on the tin — usually at least 4-6 hours — before touching it.

1 tin · Floor varnish, 2.5L

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1 each · Varnish brush or roller

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SF-10Key the surface and apply a second coatOnce fully dry, lightly abrade the surface with fine sandpaper (180-220 grit) to knock back any raised grain or brush marks, then vacuum and tack again. Apply a second thin coat of varnish the same way as before. Two coats is the minimum for a floor that gets normal foot traffic.

1 pack · Fine sandpaper, 180-220 grit

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SF-11Apply a third coat in high-traffic roomsFor hallways, kitchens or living rooms, add a third coat for extra durability, keying between coats as before. Bedrooms and low-traffic rooms can usually stop at two coats. Leave the final coat to cure fully before walking on it — check the tin, but 24 hours minimum is typical, with a week or more before rugs go back down.

1 tin · Floor varnish, 2.5L (if third coat needed)

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SF-12Clean up and move furniture backClean brushes and rollers with white spirit if you used oil-based varnish, or water if water-based. Dispose of dust bags and offcuts sensibly — fine sanding dust can be a fire risk if bagged up warm, so let it cool before binning. Wait for the full cure time before putting furniture, rugs or heavy foot traffic back on the floor.

1 bottle · White spirit, 1L

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