Block Premature Rot in Wood Deck Railings

Railings can fail long before their time if the wood isn't painted before assembly.
Railings can fail long before their time if the wood isn't painted before assembly. (By Tim Carter -- Tribune Media Services)
By Tim Carter
Saturday, September 20, 2008

Q. DEAR TIM: The wood deck railing at my home rotted prematurely and needs to be replaced. How long should deck railings last? I love mine but wonder whether I should replace it with a vinyl railing or even an aluminum one. I have been on other decks that are old, but the railings are in excellent shape. What is the secret? -- Kate M., Bean Station, Tenn.

A. DEAR KATE: I have installed new deck railings where excellent lumber failed. In almost all cases, the wood rot was caused by one of two problems: poor deck railing design or poor workmanship. Combine them on the same job, and you will have a mess in short order. However, a well-built wooden deck railing can last decades.

Years ago, my neighbor hired me to replace a deck railing that surrounded a flat roof. The railing had been painted numerous times and was built with redwood. Redwood is a fantastic material for outdoor projects, as it contains natural preservatives. But even redwood can rot.

As I demolished the old railing, I readily saw why it could never hold paint well and why it had rotted. The railing had been assembled by the carpenters before the painters had applied any paint. There were countless cut ends of the wood, as well as hidden areas where one piece of bare wood touched another. It was impossible for the painters to coat these areas once the railing had been assembled. My guess is that your railing suffered the same fate.

To prevent the same thing from happening again, I precut as many of the pieces of the new railing as possible. This was not as hard as you might think. The pieces that needed to be cut at the last moment were minimal. It was easy to predetermine the length of all of the posts, pickets and horizontal railing components.

The painter prepainted all the deck lumber, including the longer pieces I still needed to cut. Each piece of redwood was primed and second-coated with paint on all surfaces and cut edges. The end grain of each piece really soaked up the paint, and the painter coated many of these places three times. Once the deck railing was built, the painter applied the final coat.

By painting every inch of wood surface, we were able to stop water from soaking into the wood deck-railing parts. Water that enters wood through the end grain or is allowed to hide where pieces of wood overlap can start the rotting process quickly. This deck railing is now nearly 20 years old, and I can't see one place where the paint is peeling. Peeling paint on deck railings is usually a sign that water is entering the wood.

Painting those cut edges twice before we assembled the wood took extra time, but it is one secret to long life for painted wood that will be exposed to the elements.

There are many deck railing systems that are not made from wood and require little, if any, maintenance other than cleaning. You may be surprised to discover that some of them are not more expensive than the cost of rebuilding and repainting your wood deck railing. You'll have to decide if you can live with the look.

No matter which deck railing system you choose, be aware that there are strict building code requirements as to the height of the rail, the strength of the system and the spacing of the components. Safety is important. People die or are seriously injured each year when they fall from decks because of failed railings.

Tim Carter can be contacted via his Web site,

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