DeHaven Construction Company

"Specializing in Stucco, Stucco Repair, Interior Painting, Exterior Painting, Texture Coating (Texcote™) & Elastomeric Coatings"

How to Paint the Exterior of your House

The photographs in Figure 1 emphasize the importance of preparing the surface properly before applying paint. Most of the paint failures depicted are failures of preparation, or lack of a vapor barrier within the wall.

Common Paint Failures

Blistering usually indicates that moisture trapped beneath paint is caused by painting over damp wood, green wood, or a preceding coat of paint that isn’t completely dry. Such blisters contain water. Air blisters occurs when the painter fails to sand between glossy coats of paint or when the surface is too warm to be painted. Scrape blisters well, allow the wood to dry thoroughly, then spot-prime.

Peeling and flaking, though similar to blistering, suggest a moisture problem that is more widespread. They are common problems in older houses with no vapor barriers. However, if the house you are renovating has been retrofitted with insulation and vapor barrier, water may have been trapped inside the walls during installation- decidedly unhealthy condition, since the moisture can rot the structure.

To correct the condition, insert vent plugs in the siding so that moisture can escape. Excess moisture in a house can also be removed by ventilator fans. This condition can also be corrected by using a stain rather than a paint. Stain is more permeable and will allow water vapor to escape. On rare occasions, flaking occurs because a surface was too warm to pain on.

Wrinkling is caused by paint put on too thick or by painting when the exterior of a house is too cold. This condition is also common where the paint wasn’t brushed in well or paint was too thick and should have been thinned slightly. Paint should glide on; the brush should not drag. Sand well before painting again.

Alligatoring is another paint-buildup problem, often occurring after application of pain on a hot, humid day. Either an earlier undercoat did not air completely or the paint above was too thick. Scrape and/or strip.

Cracking resembles alligatoring, but it goes all the way down to the wood siding and is most commonly caused by too many layers of paint. Before painting the surface, strip the cracked paint off; scraping alone is insufficient.

Nail stains can occur where non-galvanized nails were used without being spot-primed with white shellac or sealer-primer. Sand off the rust marks and prime nail heads.

Bleeding is most common where softwood rosins bleed though the paint, especially around knots. Prime knots with primer sealer or shellac.

Chalking isn’t a problem unless it is excessive. Each time it rains, exterior paint that is aging. Scrape and repaint.

Another category of paint failure common to old houses is flaking due to exposure of wood siding to the weather. This form of flaking isn’t caused by water, as described above; rather, the wood wasn’t primed at all or was allowed to weather too long before it was painted. When paint eventually was applied, it adhered only to a top layer of degraded wood. To remedy his condition, sand the areas affected, apply a water-repellant wood preservative, and a prime as soon as the preservative is dry. Again, compare paint labels for compatibility before you begin.