Common Paint Problems – Exterior

Alligatoring:

Patterned cracking in the surface of the paint film resembling the regular scales of an alligator.

Possible Causes:

  • Application of an extremely hard, rigid coating, like an alkyd enamel, over a more flexible coating, like a Water Based primer.
  • Application of a top coat before the undercoat is dried.
  • Natural aging of oil-based paints as temperatures fluctuate.
  • The constant expansion and contraction results in a loss of paint film elasticity.

Solution:

Old paint should be completely removed by scraping and sanding the surface. The surface should be primed with a high quality Water Based or oil-based primer, then painted with a top quality exterior Water Based paint.

Berger Recommended System:

Primer: One Coat of Berger TPS Plastron Wall Primer Sealer
Finish: 3 or more coats of Berger Robbialac WeatherCoat

Blistering

Blistering paint is identified by small to medium sized bubbles or blisters under the paint film and is most common on wood siding and trim.

Possible Causes:

  • Painting in direct sunlight on a hot substrate (surface being painted) which traps solvent vapor as the paint dries too quickly.
  • Painting when the wood is damp causing trapped moisture to expand the paint film.
  • Dew, rain or very high humidity after latex paint has dried if the latex paint is of lower quality or the substrate surface preparation was inadequate.
  • House moisture escaping through the walls due to improper house ventilation.

Solution:

It may be possible to correct cracking that does not go down to the substrate by removing the loose or flaking paint with a scraper or wire brush, sanding to feather the edges, priming any bare spots and repainting. If the cracking goes down to the substrate, remove all of the paint by scraping, sanding and/or use of a heat gun; then prime and repaint with a quality exterior Water Based paint.

Berger Recommended System:

Primer: One Coat of Berger TPS Plastron Wall Primer Sealer
Finish: 3 or more coats of Berger Robbialac WeatherCoat

Mildew

Mildew is a fungus feeding and growing on the paint film or caulk and is identifiable by its grey, brown, green or dark black “splotchy” spots.

It may be possible to correct cracking that does not go down to the substrate by removing the loose or flaking paint with a scraper or wire brush, sanding to feather the edges, priming any bare spots and repainting. If the cracking goes down to the substrate, remove all of the paint by scraping, sanding and/or use of a heat gun; then prime and repaint with a quality exterior Water Based paint.

Possible Causes:

  • Combination of moisture, poor ventilation and lack of direct sunlight. Underside of soffits and eaves are especially prone to mildew.
  • Painting over a surface or prior paint film that still had mildew.
  • Not priming properly before painting.

Solution:

Old paint should be completely removed by scraping and sanding the surface. The surface should be primed with a high quality Water Based or oil-based primer, then painted with a top quality exterior Water Based paint.

Berger Recommended System:

Primer: One Coat of Berger TPS Plastron Wall Primer Sealer
Finish: 3 or more coats of Berger Robbialac WeatherCoat

Peeling

Peeling paint is a very common paint problem but can be caused either by moisture or poor adhesion. Peeling due to poor adhesion is characterized by the paint peeling and separating from an earlier paint layer (intercoat peeling) or from the substrate leaving some paint behind. Sometimes portions of earlier paint layers are visible under the curling, peeling paint layer.

Possible Causes:

  • Excess humidity or other moisture escaping from within the home through the exterior walls (less likely with Water-based paints, which allow water vapors to escape without affecting the paint film).
  • Inadequate surface preparation.
  • Use of a lower quality paint that has inadequate adhesion and flexibility characteristics.
  • Applying Water-based paint under conditions that hinder good film formation, e.g., on a very hot or cold day; in windy weather.

Solution:

If exterior moisture is the cause, eliminate the source by doing necessary repairs and maintenance; repair roof; cut heavy vegetation away from the building.

If moist air is originating from inside, consider installing vents (especially in rooms that tend to get humid such as the kitchen, bathroom and laundry room); exhaust fans and dehumidifiers may also help. Remove all loose paint with a scraper or wire brush, sand rough surfaces. Repaint with a top quality acrylic Water Based paint. It will provide excellent adhesion and allow water vapor to escape without harming the coating.

Berger Recommended System:

Primer: One Coat of Berger TPS Plastron Wall Primer Sealer
Finish: 3 or more coats of Berger Robbialac WeatherCoat