Troubleshoot Your Wood Exterior Painting Project

Algae can be identified by the green, red or brown spots that grow on damp surfaces that get extended periods of sunlight. To remove algae, wash the surface with a 3:1 bleach and water solution and scrub with a brush as needed.

You can prevent future buildups of algae by cleaning your home’s siding on a regular basis.

Mildew is a mold or fungus that usually grows in moist, shaded areas. To remove mildew, wash the surface with a 3:1 bleach and water solution and scrub with a brush as needed.

If your home’s exterior is susceptible to algae or mildew buildup, select a primer and paint that is algae- and mildew-resistant.

They leave roots, dirt and sap that work together to stain painted surfaces. To remove lichens:

• Use a stiff brush to remove as much of the growth as possible.
• Then wash the surface with a 3:1 bleach and water solution and brush.
• Finally, apply a coat of stain-blocking primer. In extreme cases, you may need to replace siding or trim affected by lichens.

Rub your hand across the siding to see if there is a fine powder, called chalking, caused by inadequate priming or overly-thin paint.

To remove the chalk, first clean the surface with a stiff brush using a Trisodium Phosphate (TSP) and water solution. Mix one cup of TSP per one gallon of water. Rinse the surface well when done.

Blistering refers to the tiny bubbles that form on the paint surface. These bubbles are caused by excessive heat or moisture.

If you find blistered spots, remove any sources of moisture. Then give the paint a few days to dry and recover; if it doesn't, pop the blisters with a putty knife.

If you can see the previous coat of paint under the blisters, the cause is excessive heat—a good reason not to paint in direct sunlight.

If you can see the natural surface of the wood under the blisters, the cause is moisture. Somehow, water has been trapped inside the siding or walls. The heat from the sun can actually draw the moisture through the walls and bubble the paint.

Check for condensation (collected water vapor) in the wall; if found, install vents in the wall.

For bathrooms, install exhaust fans to help eliminate moisture.

Also repair any drainage problems caused by the roof or gutters.

To repair the paint:

• Scrape away the blisters.
• Fill any voids with lightweight spackle.
• Sand the areas with sandpaper.
• Apply primer.

There are a number of different types of cracking paint:

• Alligatoring is paint that looks like the skin of an alligator.
• Checking is a few tiny cracks in random locations.
• Crazing is checking over a larger area.
• Wrinkling is lumpy paint that doesn’t have obvious cracks.

Causes for cracking paint include applying paint over a glossy surface, not allowing an undercoat to properly dry before recoating, applying too many coats over time or coats that are too thick, or weather wear.

To repair these problems scrape, sand and prime the affected areas.

Inspect for flaking and peeling paint. Flaking paint is caused by painting over a dirty surface. Peeling is caused by painting a soapy surface.