The Importance Of Exterior Painting

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As the seasons go by year after year, the exterior surfaces of your home are exposed to its two worst enemies; sunlight and moisture. If you don’t have a preventive maintenance program in place, these two elements will keep money draining out of your wallet.

Here’s the problem with moisture and sunlight. When surfaces are painted, the paint film is resistant to water contact from rain and dew. The problem is when moisture gets between the surface and the paint film. The paint film weakens when the loss of gloss occurs. Due to the exposure of UV rays, the life cycle of the paint film is reduced. The loss of gloss is a sign of deterioration and can be represented by “chalking”. This is one of the most common problems since the sunlight breaks down the paint’s binder leaving the pigment as powder on the surfaces. The heat of the summer and cold of winter makes the surfaces expand and contract. A good paint film will withstand the changes in temperature due to its flexibility properties.

As professional painters, Horizon will always have your back when it comes to keeping your house in tip-top shape; as such here’s our handy guide to the most common problems that arise on the exterior of your home, and the causes.


Description: Patterned cracking in the paint film resembling the scales of an alligator.


  1. Application of a hard drying topcoat over a non-drying coating;
  2. The top coat drying too quickly from being in the sun;
  3. Natural aging of oil-based paints. As temperatures fluctuate, the constant expansion and contraction forces result in the loss of paint film elasticity and eventual cracking.


Description: Bubbles resulting from localized loss of adhesion and lifting of the paint film from the underlying surface.


  1. Painting a warm surface in direct sunlight;
  2. Application of oil-based or alkyd paint (oil based) over a damp or wet surface;
  3. Moisture escaping through the exterior walls;
  4. Exposure of latex paint film (water-based) to a dew, high humidity, or rain shortly after paint has dried, especially if there was inadequate surface preparation.


Description: Formation of fine powder on the surface of the paint film during weathering, which can cause color fading. Although some degree of chalking is a normal, desirable way for a paint film to wear, excessive film erosion can result in heavy chalking.


  1. Use of an interior paint for exterior application;
  2. Use of an alkyd based paint (oil). In general, alkyd based coatings will chalk more than their latex counterparts. Use a latex coating if the structure is subjected to severe sun exposure.

Cracking / Flaking

Description: The splitting of a dry paint film through at least one coat, which will lead to complete failure of the paint. Early on, the problem appears as hairline cracks, later flaking of paint chips occurs.


  1. Older substrates with multiple layers of paint;
  2. Overthinning the paint or spreading it too thin;
  3. poor surface preparation, such as not using a primer over bare surfaces prior to the painting;
  4. Painting under cool or windy conditions that make latex paint dry too fast;
  5. Use of low quality paints, which will not adhere properly and have poor flexibility.


Description: It is often seen as a white fluffy deposit of salt crystals on cementitious wall surfaces. It depends on the presence of salt and moisture. The growth of crystals will continue as long as both are present. The salts are present in the mortar blocks or concrete structure and the moisture is usually attributable to some building defect. When emanating from mortar in brick or block buildings, efflorescence will appear as narrow bands corresponding to mortar joints.


  1. Failure to adequately prepare the surface by removing all previous efflorescence;
  2. Excess moisture escaping through the exterior masonry walls from the inside;
  3. Insufficient curing time for new cement or mortar.


Description: Premature and/or excessive fading of the paint color, which often occurs on exterior surfaces facing southern and western exposures. This is relatively easy to see because hidden areas such as eaves will not usually fade. Fading/poor color retention can also be a result of chalking of the coating.


  1. Colors will fade slightly when exposed to intense sunlight;
  2. Use of an altered paint, leading to rapid degradation (chalking) of the paint film;
  3. Use of paint colors that are vulnerable to UV radiation, most notably, lighter reds, yellows, and oranges.

Mildew and Algae

Description: Black, gray, or brown spots or areas found on the paint film or caulk bead.


  1. Continuously high humidity or dampness. As the humidity increases, mildew growth becomes more rapid;
  2. High average temperature;
  3. Poor ventilation. Still air increases mildew growth on any surface that provides a nutrient, even dirt;
  4. Mildew occurs more often on light colors of the paint film. colors that do not absorb the sun’s heat provide a surface for mildew growth. Dark colors become hot and discourage mildew growth;
  5. Cement based products are more prone to support algae growth.


Description: Paint or coating lifting from a surface due to poor adhesion. Peeling may involve one or several coats.


  1. Excessive moisture in the substrate – more likely if paint is oil based;
  2. Painting over a dirty surface; i.e.-wax, mildew, grease, chalk;
  3. Inadequate surface preparation;
  4. Applying an oil-based paint over a wet surface;
  5. Earlier blistering of paint – see blistering; (6) Use of poor quality paints.

Tannin Staining

Description: Brownish or tan discoloration appearing on the paint surface due to wood tannins migrating from the substrate through the paint film. Tannin staining typically occurs with “staining woods,” such as redwood, cedar, and mahogany, or overpainted knots in certain other wood species.

Causes: All woods, but especially red-colored woods, contain a water-soluble dye called tannin. Tannin is not soluble in most solvents. Application of latex topcoats directly to these red-colored woods may develop a red-colored stain on the finish coat. If the dry film is intact and discoloration occurs at a later date, then staining is being caused by water moisture within the board wall. This moisture will migrate and eventually carry staining substances from within the wood to the surface of the paint film.

If you are in need of exterior painting for your house, the 3 most important things to remember:

  1. Hire professionals – Painting the exterior of a home is a much more in-depth process considering many situations need to be taken into account. It’s exposed to a multitude of elements, like sunlight, moisture, temperature, etc. Professionals like Horizon will know when its the right time to paint your exterior, in addition to providing solutions for non-weather related conditions (poor ventilation, improper staining, painting over a wet coat, not prepping the surface, etc).
  2. Do not skimp on paint quality! A high-quality exterior paint will last much longer.
  3. Preventative measures are worth it – Routine maintenance of your house’s exterior paint is very important.

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