Paint damage on exterior wood surfaces can result from any number of causes. Blistering, peeling, alligatoring, wrinkling and chalking are the most common problems typically caused by improper surface preparation, use of the wrong paint and painting tools, structural problems that trap moisture in the wood, and just careless painting.

If exterior paint problems are plaguing you, first diagnose the cause of your paint problem, then prepare the surface, select an appropriate stain or paint, and apply the finish.


Blistering - Blisters appear in paint when water or solvent vapor is trapped under the paint. Water blisters are caused by water escaping from damp wood and solvent vapors are caused by painting in direct sunlight or on wet wood. Each require different treatments.

Cut the blister open. If you find bare wood underneath it's a water blister, but if you find paint it's a solvent blister.

Alligatoring - A checkered pattern of cracks resembling alligator skin results when the top coat of paint is applied before the bottom coat is dry, or when the bottom and top coats of paint are incompatible.

Wrinkling - This is the result of careless painting. If paint is applied improperly, i.e., too quickly, the top surface dries too rapidly and the paint underneath droops.

Peeling - Anytime paint peels or curls away from the wood it's an excellent indication that the paint was applied over dirty, greasy, or wet wood or over loose paint.

Chalking - High quality exterior paint is designed to chalk so rain will clean dirt from the surface. But chalking that comes off when you rub against the surface indicates the surface was not adequately primed or was finished with poor quality paint.

Once you diagnose the problem, the next step is to prepare the painting surface accordingly. Wood surfaces must be clean, dry and in good condition. Damaged boards, trim or shingles and structural damage that allows water to penetrate must be repaired.

Remove dirt and loose, peeling or blistering paint with a stiff wire brush, paint scraper, or better yet, a pressure washer. Where paint damage is severe, remove paint down to the bare wood. If any sound paint remains, feather the edges with a medium-grade sandpaper, followed by a fine-grade sandpaper. Use a power sander for areas where extensive sanding is involved.

Wash off all grease and dirt with a mild detergent, then hose it off and let it dry thoroughly. If moisture is a problem, be sure to apply a water repellent, then prime with an oil-base prime coat and cover with at least two coats of high quality paint. Now you're ready to apply the finishing touch.

Proper equipment is imperative to make your job look professional. If you follow the right preparation procedures, and are confident you can do-it-yourself, then rent all the painting equipment you need. But if you're not confident, call a professional painter.

The best time for exterior painting is during fair, dry weather, when the temperature is between 50 and 90 degrees Fahrenheit and the morning dew has evaporated. Stop painting before the evening dampness sets in, and don't paint if it's windy or dusty, particularly if you're using a slow drying, solvent-based paint.

Apply a clear waterproofing sealer to the ends of all wood boards to prevent water penetration. In areas where heat and humidity deteriorate wood rapidly, brush a prime coat on bare or new wood and use a wood preservative before sealing.

Lastly, wood, with the exception of redwood, cedar and southern red cypress (which could be sealed to help retard color changes) needs to be painted or stained to protect it from the elements. It's best to use a finish that matches the existing one as closely as possible. Use a 2-inch brush for trim and a 4-inch brush for wider surfaces. For large areas, power rollers and paint sprayers are ideal.