Uncommon exterior paint problems

Many problems associated with paint—such as peeling and flaking, chalking, and mildew—are common. These problems are typically a normal part of the aging process of paint. However, uncommon paint problems often appear suddenly, and their unusual nature can make them a source of concern.

Some of these problems can occur while the job is in progress, which creates some anxiety on the part of the customer. However, an understanding the cause of these problems and how they can be resolved can greatly diminish those concerns.

One of the more unusual problems is “re-wetting”. As the name implies, this involves a paint film that appears dry turning back to a liquid state, or re-wetting. The cause is cool, humid weather.

While most exterior paints are weather-proof within hours of application, cool, humid weather can slow this process. The surface of the paint film may appear dry, but the paint under the surface remains liquid. Given the right conditions, such as the temperature reaching the dew point, the surface of the paint can return to the liquid state.

Re-wetting has no impact on the performance of the paint. However, it can create issues with the appearance of the paint, as runs and sags may result. Fortunately, these can usually be corrected simply by using a roller or brush to spread the paint.

Re-wetting usually occurs in the late fall and winter. Monitoring weather conditions—and stopping paint application when conditions warrant—can help prevent re-wetting.

A second uncommon problem—surfactant leaching—can occur under similar conditions. This occurs when surfactants in the paint rise to the surface of the paint and are deposited there. When they dry they can leave unsightly streaks. Again, these have no impact on the performance of the paint.

Surfactant leaching can usually be corrected by lightly washing the area and repainting. In extreme cases a coat of primer may be required to prevent the stain from bleeding through the subsequent coat.

A third uncommon problem—the formation of bubbles—can occur when fresh paint is subjected to rain. This typically happens within the first twenty-four hours of application, and usually requires a relatively heavy rain to occur.  Such rains can force water into the paint film (latex paints are permeable by water, particularly before fully curing). When the water gets trapped between the paint film and the substrate, a bubble can form.

Small bubbles will usually correct themselves as the moisture migrates out. More severe bubbles may need to be broken to allow the water to escape.

The ideal way to prevent these problems is to avoid painting when conditions might be favorable for their development. However, this is not always possible or practical. Sudden rain storms, for example, cannot always be predicted.

While unsightly and a cause for concern, all of these uncommon problems are easy to correct. Perhaps most important, none have an impact on the performance of the paint.

The proper order for your projects

It is not uncommon for my customers to undertake a number of home improvement projects a the same time. For example, they may have their roof replaced and the exterior painted. Or they may have their flooring replaced and the interior painted. Doing these projects in the proper order can save money and provide for a better job in the end.

On exterior projects, it is best to replace the roof first. The removal of existing shingles, as well as the placement of ladders, can often result in damage to fascia boards and siding.

Similarly, landscaping should be done after painting. Doing so will provide easier access to the surfaces to be painted, as well as eliminate potential damage to the freshly planted shrubbery and flowers.

On interior projects, the proper order can be even more important, particularly when new flooring is a part of the project. However, the order will be determined by the type of flooring to be installed.

As a general rule, it is best to remove any existing flooring prior to painting. The removal process can often create significant dust, and in the case of tile, flying debris can cause damage to walls and woodwork. The removal of carpet can cause damage to baseboards, and walls can be easily scuffed. An alternative to completely removing carpet is to cut away a few inches adjacent to the baseboards. Not only will this eliminate damage to the freshly painted surface, it will allow us to paint the baseboard below the carpet line.

It is generally best to install new tile, wood, or laminate floorings prior to painting. Even with the most extreme care, installers can easily mar freshly painted surfaces.

Wood flooring presents a unique problem. The installation process requires substantial sanding, and the dust can accumulate on the walls. Removing the dust from a freshly painted wall can easily damage the paint. Consequently, it is best to have the floors installed and sanded prior to painting.

Having the floors completed prior to painting however, presents challenges to the painting crew. As with paint, the freshly applied polyurethane on the floor can be easily damaged, even with the use of drop cloths and other protection. Consequently, it is best to have the painting performed before the floors are completely finished.

At the completion of the painting, the flooring company can apply their final protective coatings and install shoe moulding. With the proper care, no damage will be done to the freshly painted surfaces.

Following the proper order can require careful coordination between the home owner and contractors. But in the end you will wind up with a better looking job.

Elastomeric Coatings

While a brick veneer can add warmth and beauty to a house, it is often desirable to paint bricks, particularly on older homes with considerable damage to the bricks and mortar. Paint can help hide these defects and provide a uniform finish.

An acrylic latex paint is an acceptable coating for bricks and other masonry; however, it is not always the best product to use. An elastomeric coating can provide greater durability. In addition, elastomerics have a greater ability to stretch, which allows them to bridge the small cracks which often develop in masonry surfaces.

In many ways elastomerics are similar to top-quality latex paints. Both contain acrylic resins and are water-based.

However, the film thickness of elastomerics is considerably greater, which contributes to its durability. Most manufacturers recommend a film thickness of 1 to 1.5 mils for latex paint, while recommending a film thickness of 4.5 to 5 mils for elastomerics.

The thicker recommended film results in substantially greater material usage- a gallon of latex paint will cover about 350 square feet while a gallon of elastomeric will cover about 125 square feet.

Achieving this film thickness also requires more labor, as the application of elastomerics is a slower process. Though the initial cost is higher, elastomerics are a cost effective coating for masonry surfaces.