How to repair a wooden door: dents, gaps and swollen bottoms

What you need

• Screwdriver or drill driver, and a hammer with a thick nail to knock out the hinge pins
• Flexible filling knives, 3 and 8 cm
• Sanding block with 80, 120 and 240 grit paper
• Hand plane, orbital sander or electric planer
• Craft knife, pencil and ruler
• Trestles or two chairs with a blanket to rest the door on
• Self-adhesive fibreglass mesh for holes in board (Leroy Merlin, Bricodepot)
• Water-based wood filler and two-part epoxy filler (Ceys, Pattex, Loctite)
• White carpenter's glue (Titebond, Pattex)
• Wood sealing primer and water-based enamel (Bruguer, Titanlux, Montó)
• Sealer or bottom-edge epoxy for wood exposed to damp (Xylazel or two-part epoxy)
• Masking tape, plastic sheeting to protect the floor

Step by step

1. 1

   Identify the type of door

   Knock on the panel with your knuckles. A hollow sound means a plywood door with a cardboard honeycomb core, very common in 1990s and 2000s flats in Valencia and Alicante. A dull sound means solid or chipboard core. An edge with a strip of wood and thin veneer means a veneered door.

2. 2

   Take the door off if you have to work on the bottom or corners

   With the door slightly open and a wedge underneath, knock the hinge pins out from below with a thick nail, or unscrew the hinges. Get help: a plywood door weighs 12-18 kg. Rest it on two trestles with a blanket.

3. 3

   Small dents and sunken areas

   Sand off loose paint and the edge of the dent with 80 grit. Fill with water-based wood filler in 3 mm layers, leaving 1 mm proud. Leave to dry for 1-2 hours, sand flush with 120 and 240 grit and prime before painting.

4. 4

   A hole in a hollow door

   Trim the splintered edges of the hole with the craft knife to leave a clean outline. Stick a self-adhesive fibreglass mesh patch on the outside, a little bigger than the hole. Apply epoxy filler over the mesh in two layers of 2-3 mm, leaving it to dry between coats as the tin says. Sand flush.

5. 5

   Broken corners or edges

   Remove splinters, glue back any pieces you can recover with white glue and hold them with tape. If material is missing, fill with epoxy filler, shaping it with a dampened knife and leaving it proud. Once cured, sand flush with the door using a sanding block.

6. 6

   Old knob or lock holes

   If you have changed the handle and the old hole is bigger than the new one, glue in a round wooden plug (a 25-35 mm dowel), leave it for 2 hours, trim flush with the craft knife and sand. Then drill the new hole with a hole saw. There are separate guides on loose door handles.

7. 7

   Bottom swollen by damp

   Measure the swelling by comparing the bottom with the top. Leave the door somewhere dry and ventilated for 3-5 days and check that it has stopped swelling. Mark the trim needed in pencil, which should not exceed 5-8 mm on thin plywood, and plane or sand the bottom edge along the grain.

8. 8

   Seal the bottom edge

   The bottom edge is where water gets in when you mop. Apply two coats of sealing primer or epoxy to the bottom and to the lower 5-10 cm of both faces, and a third of enamel. A door sealed underneath lasts years longer without swelling.

9. 9

   Sand, prime and paint

   Sand the whole panel with 120 grit to take the shine off, wipe off the dust and prime the repaired areas. Paint with two coats of water-based enamel in white or a colour (the detail is in how to paint a wooden door). Leave it to dry for 24 hours before closing the door.

10. 10

    Rehang and check the gaps

    Hang the door and check that you have a 3-4 mm gap at the sides and top and 8-10 mm at the bottom above the finished floor. If it rubs, see door rubbing on the floor and adjust the hinges.

Repairing a plywood or wooden door: types of damage and the fix

A plywood door, the most common in Spanish homes built between 1980 and 2010, is a timber frame with two thin 3-4 mm panels and a cardboard honeycomb core. It is light, cheap and fragile: a knock from the handle of the door opposite, a child's kick or a suitcase can puncture the panel. Solid board or pine doors, by contrast, dent but do not puncture.

There are four common types of damage. Knocks and scratches are superficial and are fixed with filler. Holes go through the whole panel and need reinforcement behind. Broken corners and edges are rebuilt with epoxy. And swollen bottoms show that water has got in through the bottom edge, which is common in kitchens, bathrooms and coastal homes where floors are mopped with a lot of water.

Common mistakes when repairing a door

• Painting without priming the filler. The shade shows and the paint absorbs differently, leaving marks.
• Trimming the bottom before it has dried. If you cut with the wood damp, a 10 mm gap is left once it dries.
• Forgetting the bottom edge. It is the spot most exposed to the mop; if you do not seal it, the swelling comes back.
• Filling a large hole with filler alone. Without mesh or reinforcement it sinks. Use a patch and epoxy.
• Planing the whole door when it only rubs in one corner. First check whether a hinge has worked loose: how to adjust door hinges.
• Thinking more filler means more strength. Non-structural filler will not hold hinge screws or lock screws.

When to call a professional

Call a carpenter if the door frame is damaged, if the hole covers more than a third of the panel, if the door is solid or hardwood with a finish you do not want to lose, if the swelling is more than 1 cm, or if several doors have the same problem (usually a leak or damp in common). It is also worth it if you have no help to take a door off: with the door on trestles we can plane it in 30 minutes.

With Manitas Costa, adjusting a door that rubs or will not close costs €40-70, replacing hinges (3) €50-90 and fitting a new interior door €90-150 labour, not including the door. For repairs to dents, filler and paintwork we apply our hourly rate: first hour €35-45, following hours €28-35. Fixed price before we start, payment when finished and a 6-month guarantee on labour.

See carpenter at your home, carpenter prices, and availability in Valencia or Alicante. If you want to repaint after repairing, see how to lacquer doors white.

Coastal damp and door bottoms

On the coast, door bottoms are the first thing to swell. The reason is simple: floors get mopped with water, unsealed plywood soaks it up through the bottom edge, and the humidity in the air does the rest. In poorly ventilated bathrooms, the door absorbs steam from showers all year round, and in beach homes the salt air speeds up the deterioration of hinges and screws.

If you live in a building where the comunidad de vecinos (residents' association) has rules on noisy works (almost all limit the hours), plan the sanding and cutting within those windows and work with a vacuum attached to limit dust. Working on the landing or the shared terrace without protection can cause annoyance and complaints.