Clear finish failure on timber

Cause

UV light causing breakdown of the timber surface under the clear finish

Repair

  • clear or lightly pigmented coatings are vulnerable to ageing of the underlying timber and loss of coating adhesion under UV light from the sun
  • some timber producers do not recommend clear finishes for timber elements fully exposed to the sun
  • clear finishes exposed to the sun are likely to need frequent recoating – this could be as often as every 2 or 3 years, or even less in extreme circumstances
  • scrape or sand off the existing coating to give a clean, as-new timber surface. Apply the selected coating. If you want to avoid frequent rework, opt for a coating such as a good quality paint that is likely to have a much longer lifespan

Cause

Moisture was absorbed into the timber, typically at the ends of boards or around fixing points

Repair

  • identify and address the cause of moisture. For example, if the surface is on the house exterior and is wet for long periods because of broken spouting or very close planting that slows down drying, fix the spouting or cut back the planting
  • if the affected surface is on the inside, for example around windows, again identify the cause and address it. If you suspect there may be extensive or multiple leaks, consult a registered building surveyor for advice
  • allow the timber to dry thoroughly before beginning repairs
  • scrape or sand off the existing coating to give a clean, as-new timber surface. Apply the selected coating, taking particular care with the application around the ends of boards. If you want to avoid frequent rework, opt for a coating such as a good quality paint that is likely to have a much longer lifespan