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    • How to fill cracks, holes, dents & splits in exterior timber surfaces

How to fill cracks, holes, dents & splits in exterior timber surfaces

Exposed timber surfaces such as weatherboard, decking and fencing can suffer from weathering and damage. Painting is a great way to freshen up tired looking timber but if there are cracks, rotted areas or holes, painting will only mask the problem. Itís important to properly repair and fill damaged timber surfaces so that problems donít return and you can enjoy an excellent finish. 

You'll need: 

  • Polyfilla Exterior Timber
  • A flexible filling blade 
  • A scraper
  • Sandpaper


  1. Ensure surfaces are clean and dry and remove any rotted timber and fix split timber firmly before filling. Priming is not necessary. 
  2. Apply Polyfilla Exterior Timber firmly using your filling blade. Scrape off any excess to save time sanding. Allow to dry for 2-3 hrs in thin 2-3mm applications depending on humidity. For deeper jobs apply in 10mm layers, allowing each layer to dry completely before applying the rest.
  3. Sand back to a smooth, even surface and paint with a quality exterior water or oil-based paint, or stain and clear varnish.
  4. For a smoother finish allow filler to dry, sand back and apply another very thin coat of filler. Allow this to dry then sand lightly with fine (>300 grit) sandpaper before painting or varnishing.
  5. Protect from rain until painted over and for best results apply undercoat before applying exterior top coat.