You’ve just finished up a beautiful deck in your backyard, complete with an intricate railing that encompasses it. But if there still seems to be some little detail that’s missing, it could be those plain old 4×4 posts. So to give your project that perfect finishing touch and showcase your carpentry skills even further, consider topping things off with some post caps.


Wooden caps are the least expensive of the post-cap options, and come in a wide variety of styles from simple to ornate. Most caps are made from cedar, but you can also find redwood and other woods, as well as synthetics that match some of the popular engineered decking materials. 

One of the most common wooden caps is a square block of 2×6 that has been beveled four times on one face, creating a squat pyramid shape on top. Other styles might have a more truncated pyramid shape, beveling up on four sides to a flat top, or they may be any of a variety of routed designs.

At its simplest and least expensive, the wood cap is simply flat on the bottom, and is installed by nailing or screwing it to the flat top of the post. Upgraded versions are either routed on the bottom or utilize four pieces of molding to make a 3½-inch by 3½-inch square on the underside of the block. Either method forms a recess on the underside of the block that allows it to drop over the top of the post for a much more finished appearance. This type of block can also be nailed or screwed in place, or you can use finish nails through the moldings.


A step up in looks and durability–and also in price–are post caps made from aluminum or copper. Aluminum caps are typically solid cast aluminum in the traditional pyramid shape, with a molded recess on the bottom that fits over a standard 4×4 post. Aluminum caps are either painted or powder-coated in colors such as white, green and brown. Powder-coating is a mechanical process that bonds the color to the metal for greater durability.

Copper caps are usually a copper sheet that is formed over the top of a wooden cap, again most commonly in the pyramid shape. The copper may cover the entire top of the wood cap, or it may be a small copper piece that sits on top of the wood, so that both the copper and the wood are exposed on top. The copper can be sealed with a spray lacquer to maintain its shine, or allowed to weather naturally.


Doing double duty as both a post cap and a deck light is the low-voltage post cap light. These 12-volt lights are powered by a 110-volt transformer, and are available in a couple of different styles that feature flat or pyramid shaped tops, usually with frosted glass sides. Here again, these are most commonly powder-coated aluminum in any of a variety of colors.

Post-cap lights can be used on every post if desired, but a much more common approach is to use them only on the corners, then use matching or complimentary aluminum caps on the other posts. For long deck rails, additional lights may also be located on some of the intermediate posts. 

Lighting transformers need to be sized to the number of lights in the system, and there are different size transformers available that will power from as little as three or four lights up to ones capable of handling 15 or more. The transformers are typically equipped with either a timer or a photocell, or both, to ensure simple, automatic activation of the lights.

Post caps are available from most home centers, lumber yards and other retailers that carry lumber products, either in stock or by special order. Post cap lights are usually available from the same sources, as well as from retail electrical suppliers and lighting shops.


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