Cracking on exterior surfaces

Problem - Cracking on exterior surfaces
Dry paint film cracks and splits through at least one coat. Early on, the problem appears as hairline cracks; but later as paint chipping and flaking (see Flaking). The paint may crack in the surface direction or in a chequered-like pattern (see Alligatoring).

Possible causes

  • Old paint surface with too many existing coats.
  • The surface was originally painted with an oil-based paint.
  • Too much thinner or an inappropriate thinner was used, or the coat is either too thick or too thin.
  • The paint is not suitable for the surface.
  • The surface is wet.
  • Excessive expansion and contraction of wood due to moisture.
  • Wooden panelling is insufficiently ventilated.
  • Poor surface preparation.


Remove loose and flaking paint with a scraper or wire brush. If the paint coat is too thick, remove it entirely.

Clean off all dirt and mould from the surfaces with Tikkurila Homeenpoisto according to instructions on the label (see Mould). Rinse thoroughly and allow to dry.

Before application, ensure that the surface is completely clean and dry. Apply primer to the clean wooden surfaces. Finish with a suitable Tikkurila exterior paint according to instructions. Avoid applying thick coats.

Do not paint in direct sunlight. The best weather for painting is when it is warm and overcast. See the product label for information on painting conditions.