Fill a hole in a hollow-core door

Fill and finish a hole in a hollow-core door by backing it first, then filling, sanding and painting to match.

FD-01Set up your workspaceLay a dust sheet down and lift the door off its hinges if you can manage it alone — it's much easier to repair flat. Rest it across two trestles or a pair of workbenches, or lay it on an old blanket on the floor. If the hole is near the handle, unscrew and remove the handle and any escutcheon first.

1 each · Dust sheet

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FD-02Clean up the holeCut away any crumbling paper skin or splintered edges with a sharp trimming knife until you reach firm material all round the hole. Pull out any loose honeycomb card from inside the door with your fingers or a small screwdriver. Vacuum out the dust and debris so the filler has a clean surface to grip.

1 each · Trimming knife

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FD-03Support the hole from behindA hollow door has nothing behind the skin, so filler on its own will just fall through. For a hole up to about 20mm, push scrunched newspaper or a squirt of expanding foam just below the surface as a backing. For anything fist-sized, cut a piece of thin card or plywood a bit bigger than the hole, thread wire or string through its middle, feed it in at an angle, then pull the wire taut so the patch sits flat against the inside face. Tie the wire round a pencil laid across the hole to hold it under tension while you fill.

1 roll · Garden wire or string

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1 each · Thin card or plywood offcut

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1 each · Expanding foam filler (small can)

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FD-04Fill the holeTwo-part wood filler sets hard and holds better in a hollow door than ordinary multi-purpose filler, which can be too soft over an open gap. Mix it according to the pack and press it firmly into the hole with a filler knife so it grips the backing, building it up slightly proud of the surface. Multi-purpose filler will work on small holes but expect to build it up in two or three thin coats, letting each one dry first.

1 each · Two-part wood filler kit

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1 each · Filler knife

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FD-05Trim the wire and top upOnce the first fill has gone hard, snip the wire or string flush with the surface using pliers or side cutters. Check the repair for any dips or shrinkage and apply a thin second coat of filler to bring it level with the surrounding door.

FD-06Sand it smoothOnce the filler is fully cured, sand with a medium-grit paper first to knock down high spots, then a fine grit to blend it into the surrounding surface. Wipe away the dust with a slightly damp cloth and let the door dry before painting.

1 pack · Sandpaper (medium and fine grit)

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FD-07Prime the repairBare filler is porous and will show through paint as a dull patch, so seal it first. Brush a coat of wood primer or undercoat over the filled area and a little beyond, feathering the edges, then let it dry fully.

1 each · Wood primer/undercoat, 250ml

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1 each · Small paintbrush

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FD-08Paint to matchOnce the primer is dry, apply the topcoat that matches the rest of the door, feathering your brush strokes into the surrounding paintwork so the repair doesn't show. Leave to dry, then check under good light and add a second coat if needed.

1 each · Matching topcoat paint, 250ml

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FD-09Rehang the door and tidy upOnce the paint is fully dry, rehang the door on its hinges and refit the handle and escutcheon. Sweep up any dust or offcuts and dispose of the leftover filler and foam can according to the packaging instructions.

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