Common Problems with Exterior Wood

A man scraping an old garage that needs paint.

Wood, more than other materials, takes a beating from the elements, be it direct sunlight or heavy rains. Because wood is prone to more difficulties than masonry or engineered materials, you have to take precautions with paints and finishes, applying them in a timely manner, but also routinely monitor the wood's condition throughout the course of the year. Whether you have a wooden deck or wooden siding, by applying the right paints, finishes, and preservatives you can head off many problems. Still, some problems will arise in the course of the wood's life.

Flaking Paint

Flaking paint can be a common problem with wood exteriors. Often times, flaking is due to paint that was applied to a dirty or greasy surface, but it is equally common for a fair amount of sun and rain to result in flaking as well. To remedy this, use a scraper and remove the flakes along with other questionable spots. Sand the surface and reapply primer, allowing it to dry before finishing it with a fresh coat of paint.


Mold can be a big headache for exterior wood. Mold always indicates a moisture source, which must be eliminated before any repainting can begin. If you can get rid of the problem — a leaking gutter for instance — then you can correct the issue. Wash the area with a fungicide and rinse it thoroughly. If you need to resurface and repaint, you can do it then.

Dry Rot

Like mold, rotting wood is frequently caused by water, but it may also be due to wood-eating pests like termites. Extreme problems of rot usually call for a replacement of the wood. If the problem is contained in small, localized areas, you may be able to cut away the damaged material and fill the area. Then you'll need to prime and repaint. By keeping up the maintenance and checking up regularly, you can usually head off this problem early. If you let that paint job go, problems like this are sure to creep in.


Bleached or discolored wood is an issue for bare and preserved wood. If you want a natural look to the wood and don't plan to paint it, try a wood cleaner to restore its natural color and tones before coating it with a natural finish.


A very common problem for joints and panels is cracking, which is caused by continued expansion and contraction due to the weather. The cracks are then subject to water penetration, which if left unchecked, can cause rot and other damage to your wood. To fix this, the cracks must be raked out and then treated with filler that will flex with the expanding and contracting. Finally, prime the areas and then repaint.

Crumbling Putty

Loose and crumbling putty is a common problem for windows. As glass expands and contracts because of the weather, it allows moisture to seep inside and can cause the putty to deteriorate. If it is not handled soon, it may eventually damage the wood. Intense sunlight can cause the putty to crumble as well. Simply the fill the cracks in the putty to fix it.

Visible Knots

Seeing knots throughout your paint job is common, but it could have been warded off by sealing the knotted areas before priming. If you did seal it, sometimes direct sunlight will still allow them to seep through. To correct this issue, remove the sap and reseal the knot. Be sure that no sap remains deep down in the knot. A heat gun may remove the sap from the deep crannies. Then, you need to resurface and repaint the area.

A wood exterior requires continual care. Small problems will almost always evolve into big messes if not taken care of right away. Take great pains with wood before you paint it by sealing and priming it carefully. Wood is not a forgiving element if you make any mistakes or find yourself taking a shortcut. On the other hand, wood is one of our most basic building blocks and produces some of the most beautiful architecture from rustic cabins to those stop-you-in-your-tracks painted ladies. Deal with these issues right away and your wood will last much longer.