If your door is beginning to look a little worse for wear, or you are about to install a brand new door, it must be properly treated. External wooden doors are exposed to damage from the elements – sun, wind, rain and extreme temperature changes – and must be treated to prevent this damage. Untreated doors can become swollen, warped or cracked, which not only make the doors unsightly, but also can cause it to stop functioning properly. Painting or sealing a door can be a simple task but must be done correctly.

Here are some tips on making the process as easy and effective as possible:

Whether you are painting, sealing or varnishing your door, there are a few basic rules. Ensure that all cracks and holes have been filled and sanded smooth. Existing doors should have all the door furniture – handles, locks etc – removed if possible. The door should be detached from the frame and place in a well ventilated area for working on.


  • Make sure your door is smooth. Peeling flakes of paint can cause imperfections in the second layer of paint you apply. If there are any lumps or flakes, sand them down before you set about applying your new coat of paint.
  • If you are painting a wooden door, you should apply primer to the woodwork before you begin applying paint, giving the primer or sealant plenty of time to dry too.
  • If you are happy that your door is properly sealed and dried, you can begin painting. You ought to apply an undercoat if you are painting directly over old paintwork. This will prevent discolouration. Apply as many layers as suggested by the paint manufacturers.

Sealant or Varnish

  • If you choose to stain your wooden door, then this must be done prior to applying any sealant. Stain alone will not offer protection, and a good quality varnish or sealant must be used once the stain has dried. If you are applying sealant, you must apply it directly to the wood. This means that if you are changing your door from painted to natural wood, you must remove all the paint before you apply the sealant.
  • It is best to use a lighter finish for doors that will be directly exposed to regular sunlight. Dark colours absorb more heat, and damage can be caused to the door after a lengthy exposure to sunlight.
  • Apply as many coats as recommended by manufacturer, but leave ample time for each coat to dry before applying the next layer. The same applies to paints.
  • Once the sealant has dried, you should notice a slight rough feel of the door. This is just a sign that the sealant has worked effectively, and any noticeably uneven areas can be sanded down.

Painting or sealing your door can add years to the life of the door, and if done thoroughly with a good quality paint or varnish it will last for many years.