Common Exterior Paint Problems

Properly applying exterior paint is a bit more difficult than it appears and it can be frustrating when you don't notice mistakes until all is said and done. If you just completed an exterior painting project and notice cracking, blistering, or some other imperfection, don't worry, many paint problems are easy to fix! This buying guide explores solutions to the most common problems that do-it-yourselfers face upon completing an exterior paint project.

Alligatoring

Alligatoring is a term used to describe a type of cracking in the paint surface that resembles an alligator's scales.

Potential Causes

Applying a topcoat of paint before the undercoat has dried
A natural loss of paint elasticity over time due to temperature variations
Using a hard or rigid coating over a flexible latex primer

Solution
Completely remove all coating by scraping and sanding or by using a power washer. After the coating has been removed, prime and paint the surfaces with an exterior primer and paint.

Blistering

Blistering refers to the appearance of bubbles on a painted surface. Blistering is the result of a loss of adhesion, which can be caused by a number of naturally-occurring circumstances.

Potential Causes

The painted surface is in direct sunlight, causing it to be too warm to maintain adhesion
Latex paint has been exposed to dew, high humidity, rain, or moisture shortly after application, worsened by proper surface preparation
Surface was painted while still damp

Solution
If the blisters go down to the substrate, try to remove the source of moisture. Repair any loose caulking and remove the blisters by scraping the paint off and then sanding the surface. If you believe excess moisture was the cause of the blistering, try to identify and repair the problem. Then, prime and repaint the surface.

Chalking

Chalking is an easy-to-identify paint problem in which a white powder forms on the surface of the paint. The white powder creates a faded appearance of the paint color. While some chalking is normal, it can have a negative effect on the curb appeal of your home.

Potential Causes

Use of incorrect paint, such as interior paint or low-quality paint with a bold pigment
Coating has been over-thinned
Natural weathering

Solution
Remove as much of the chalk residue as possible by power washing it or using a stiff bristle brush; rinse thoroughly. After the surface has dried, check for any remaining chalk by running your hand over the surface. If chalk is still present, wash again. After it has dried completely, repaint the surface with a high-quality exterior latex paint.

Cracking/Flaking

Cracking or flaking is the splitting of paint film on a surface. Initially the problem will appear as small hairline cracks, but if left untreated it will eventually lead to flaking paint.

Potential Causes

Exterior wood or plywood expands and contracts as temperatures fluctuate, causing the paint to crack
Inadequate surface preparation
Application of an overly-thin coat of paint

Solution
If the cracking does not go down to the substrate (the surface that was repainted), try to remove the loose flaking paint with a scraper. After this is complete, sand the edges and then prime and repaint the surface. If the cracking does go down to the substrate, remove all of the paint by scraping and sanding. Then, prime and repaint the surface with an exterior primer and paint.

Fading

Fading, like chalking, is quite simple to spot. Paint that has faded or simply not retained its color is typically found on surfaces that are exposed to frequent sunlight. When fading occurs, you will notice that surface areas that are somewhat shaded from the sunlight will not exhibit the same loss of coloring.

Potential Causes

Exposure to intense sunlight, especially if the paint is a bright shade of red, blue, or yellow
Use of low-quality paint
Excessive tinting of the paint

Solution
Power wash the surface to remove chalk and other contaminants. Prime bare areas and recoat the entire surface with an exterior paint.

Frosting

Frosting is a term used to describe a white, salt-like substance that appears on a painted surface. While frosting may appear on any paint color, it is far less noticeable on white or light-colored paints.

Potential Causes

Painted surface is largely hidden from natural rainfall and other forms of moisture, causing buildup of the substance

Solution
Paint affected by frosting should be completely removed using a wire brush if the paint is on masonry or by sanding if the paint is on a wood surface. Afterward, apply an exterior primer and then recoat the surface with an exterior paint.

Mildew

Mildew is one of the peskiest exterior paint problems, as areas of fungus growth can be found on the surface of the paint or on other surfaces in damp and shaded locations. When dealing with mildew, take proper safety precautions by wearing protective eyewear and waterproof gloves. Before taking action, confirm that you are dealing with mildew by applying a few drops of bleach to the affected area and then rinsing. If the dark spots disappear, then it’s most likely mildew.

Potential Causes

Painted surface is located in a damp area with no direct sunlight
Substrate had mildew and was painted over without the removal of the mildew

Solution
Remove all mildew from the affected surface by power washing or scrubbing it with a diluted bleach solution (one part bleach, three parts water). Rinse the surface thoroughly and allow it to dry. Then, apply a new coat of exterior primer and paint.

Efflorescence

Crusty, white salt deposits, which are leached to the surface of mortar or masonry as water passes through it. Efflorescence is often seen as a white fluffy deposit of salt crystals on cementitious (e.g. masonry) wall surfaces. Efflorescence depends on the presence of salt and moisture, and 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.

Potential Causes

Failure to adequately prepare surface by removing all previous efflorescence.
Interior moisture escaping through the exterior masonry walls.
Exterior moisture driven through masonry walls by wind and rain.
Basement walls that are not properly sealed against ground moisture penetration.
Insufficient curing time for new cement or mortar.

Solution

If excess moisture is the cause, eliminate the source by repairing the roof, cleaning out gutters and downspouts, and sealing any cracks in the masonry with a quality caulk or sealant. If moisture is originating inside the building, consider installing vents or exhaust fans, especially in kitchens, bathrooms, and laundry areas. If moisture is being driven through the walls from the outside, apply a waterproofing coating to the outside. Remove the efflorescence and all other loose material with a wire brush, power brush, or low-pressure washing, and then thoroughly rinse the surface. If the surface is highly alkaline, wash with a mild solution of H&C Concrete Etching Solution or Muriatic Acid. Painting should be delayed if efflorescence continues.

Prevention

While some of the issues discussed above are caused by natural elements, it is often possible to prevent exterior paint problems by properly prepping the surface ahead of time. Before painting, be sure to check for the following problems and address them as needed:

Loose or peeling paint should be removed with a paint scraper or stiff wire brush. Then, sand the surface until it's smooth. Wash, rinse, and allow the surface to dry before you begin painting. Any bare areas should be spot primed before applying a top coat.
Mildew should be treated with a solution of three parts water to one part household bleach; leave the solution on the surface for 10 to 20 minutes. Then wash, rinse, and allow the surface to dry before painting, and apply a topcoat.
If there is a glossy sheen on the surface, it should be lightly sanded to a duller finish. Fine-grit sandpaper is best; however, tougher jobs like removing stained, peeling, or splintered areas will require medium grit sandpaper. Then, wash, rinse, and allow the surface to dry.
If chalk is present, wash the surface thoroughly using a household detergent and a stiff bristle scrub brush. Rinse and allow the surface to dry before painting.

Once you've addressed any existing issues with the surface you'd like to paint, it's time to follow these instructions to properly prep the surface for painting:

Starting at the top, wash down the surface using a garden hose with a high-pressure nozzle or a power washer. A house wash may be used for cleaning exterior surfaces if desired.
Patch cracks, holes, and seams with exterior paintable caulk. Check for proper ventilation from the kitchen, laundry room, and bathroom where moisture may accumulate. Moisture from inside the house is the main cause of peeling paint on a building's exterior.
Prime any bare wood before painting or use a paint and primer in one product.
Apply a topcoat with a good-quality brush, roller cover, power sprayer, or paint pad by starting at the top and working down. tart with the largest exterior surface, such as siding, followed by trim, windows, and shutters.