According to a study from the Western Wood Preservers Institute the expected life of wood utility poles can be conservatively estimated at 75 years or more when they are properly inspected and maintained. Interestingly, most utility companies estimate the serviceable life span of a pole to be only 35+/- years.

Wood Utility Pole Treatments

Utility poles are usually treated with either pentachlorophenol, chromated copper arsenate, copper napthenate, or creosote. Whichever preservative treatment is used, the main goal of the treatment is to extend the life of the pole by rendering the wood useless as a food source for termites and other wood boring pests and to reduce the effects of decay caused by rot and decay. All of the treatments listed above provide excellent life spans for poles. They are usually chosen based on factors including climate where the poles will be installed, environmental impacts of the chemicals used, concerns around how the poles will be handled, and even individuals’ preferences.

The Biggest Problems for Wood Utility Poles

Most decay of wood utility poles happens at the ground line where the poles are often in contact with moisture which causes rot and decay. Wood utility poles do not have many other natural enemies other than the occasional fire, woodpecker, or car wreck. Wood utility poles are quite resilient and can withstand many natural conditions including high winds, acidic soils, and salty air – conditions steel and concrete poles may not withstand as well.

Increasing the Life of Wood Utility Poles

Properly treated wood utility poles are nearly guaranteed to last about 35 years without any inspections, maintenance, or preventative measures. However, the life span of utility poles can be drastically increased (easily doubled) through a regimen of periodic inspections and maintenance such as pole wrapping, which requires digging around the pole and literally wrapping the pole with a protective barrier. An excellent preventative measure is to coat the pole with the polymer wood coating from American Pole and Timber. The polymer coating must be applied before the pole is installed but provides a protective barrier that will prevent the need for labor intensive pole-wrapping in the future.

The study I mentioned at the beginning of this report actually suggests that utility poles can last more than 135 years (up to 260 years – yes, two, six, zero) but that over time other “degradation mechanisms” take their tolls. Typical maintenance programs are not geared towards correcting those issues which include pole top decay, pole splitting, decay at connections, and excessive weathering so the reasonable estimate of a wood utility pole should probably remain in the neighborhood of 75 years.

Applying Your New Knowledge of Wood Pole Life Spans

There is a great chance you are not in the utility business and just want to know how long your barn poles will last.? While there are no hard numbers on that – at least not that I have found YET – this study reveals that the life is probably longer than you might have even hoped.? Barn poles, fence posts, and small electric poles are treated with the same chemicals as utility poles and usually to the same retention levels using the same methods.? Though utility poles are held to higher standings of structural grading and specifications than your average barn pole you can probably expect the life spans to be similar. Again, the extended life span requires some periodic checks and maintenance.

If you are using treated poles or pilings around a marine environment, the rules are a little different since the surroundings are wetter and generally more dynamic and harsh (waves, changing tides, different organisms, constant contact with water).? Properly treated poles or pilings for freshwater applications can probably be made to last 30 years with proper preventative measures and maintenance.

Here’s some solid logic.? Think of all those old barns and fences that were built by your grandfather’s grandfather practically forever ago. While “they don’t make ‘em like they used to”, the treatments have improved.? You can expect your treated wood poles to last a lifetime.

I made a sketchcast about how to build a wood bulkhead and I wrote about how to build a wood retaining wall but I might have assumed too much about how much you know about the bulkhead materials I listed. They are slightly off the beaten path from “regular” building materials you’d find at your local hardware store so here is a breakdown of basic wood bulkhead materials.

Wood Bulkhead Materials List

Building a wood bulkhead is similar to building a privacy fence. You have posts (pilings), rails (wales), and pickets (sheets or sheeting). A bulkhead typically has great horizontal force applied against it, though, so it has more structural requirements than a fence. In order of front to back (water side to ground side) the parts of a wood bulkhead are:

• Pilings (can be round or square)
• Wales
• Center Match (sometimes call “sloppy tongue & groove”)
• Filter Cloth
• Tie Rods
• Deadmen
• Top Cap
• All the required Hardware (nails, screws, spikes, nuts, washers)

Attention: First, the materials required for YOUR wood bulkhead might be different from those I am showing below so please have your bulkhead designed and specified by a professional builder and/or designer. Also, be sure to use the proper materials for the best longevity. Using cheap materials to save money NOW is only wasting money in the long run. Use properly treated wood, galvanized or stainless hardware, and make sure the bulkhead is installed properly.

Treated Pilings

You can use round or square pilings. It is totally up to you. You might want to match your neighbors’ bulkheads or you might be concerned about costs (round pilings cost less). Either way, use properly treated wood – 2.5 pcf in saltwater and a minimum of .60 pcf in freshwater. For brackish (mixed fresh and salt) water, go with 2.5 pcf.

Wales

Wales are the horizontal boards (like the rails on a fence). Most wood bulkheads have two but some will have three or more. Wales are connected to the land-side of the pilings and will have the center match sheets nailed to them. A very common size used for wales is 3×8. You should use the longest lengths possible to minimize joints, which can become weak spots. You should be able to find 3×8-20′s from most marine construction suppliers. Many other sizes are commonly use depending upon the sizes of the bulkhead and the forces applied to it. I have seen wood bulkheads with 8×8 wales.

Center Match

Center match are sometimes called “sloppy tongue & groove” because the joint is a little loose to allow for swelling in the water so the edges will not break with regular expansion and contraction when the boards alternates between wet and dry.

Center match is usually nominal 2×10 with actual dimensions of 1.5″ x 8.9″. That is, because of the groove each board only spans 8.9 inches – very important to factor into your bulkhead materials list. I have heard of numerous people making an extra trip to the dealer (or paying for another delivery) because they were 5 pieces short of center match.

Filter Cloth

Filter cloth is kind of like a very thick felt. The purpose of filter cloth is to stop silt and dirt from seeping through the spaces between the center match while allowing water to drain and relieve hydrostatic pressure from the bulkhead after a rain – it helps maintain a cleaner appearance and keeps soil behind the bulkhead where it should be. While some people use plastic for this purpose, I truly believe a quality geotextile filter cloth is better because it allows the water to drain. Filter cloth is cheap – use it.

Tie Rods

Tie rods support the structure from behind to keep it from falling forward (into the water). Tie rods will be connected to the pilings on one end (via hold drilled from the front to back of each piling) and to deadmen on the other end. They are simply long rods with about 12″ of threads on each end for a nut.

Builders usually use tie rods that are about 3 times as long as the exposed height of the bulkhead being built. For example, a 4′ tall wall will commonly use 12′ long tie rods. The come in diameters including 1/2″, 5/8″, 3/4″, and larger. Some people use cables instead of tie rods but tie rods are stronger and they can easily be tightened if needed.

Deadmen

I have no idea why deadmen are called deadmen but I can make up some good stories about medieval times and using what you have to protect the castle if you want.

Dead men are treated posts – round or square and often cutoffs – used to “tie back” the bulkhead and support it from behind. Like the rest of the materials, the size of the deadmen used should be based upon the overall height of the wall and the load it bares.

Top Cap

Most top caps are made using a regular S4S 2×12. While they are not required, top caps will provide a little more structural integrity while giving the wall a more finished appearance from above.

Hardware

Use galvanized or stainless steel hardware when building on or near water. Screws are better than nails but more time-consuming. Generally, you will need the following hardware for your bulkhead:

• Tie Rods with 2 nuts and 2 washers for each
• Spikes (60 penny nails) to attach the wales to the pilings
• 16 penny nails (or larger) to attach the center match to the wales and the top cap to the wales
• Staples to attach the filter cloth to the center match

The materials list for a wood bulkhead is pretty simple and short. The bulkhead materials listed above will work for most wood bulkheads or retaining walls built around residential locations. If you need a reliable source for wood bulkhead materials, call the people at Building Products Plus in Houston, TX who let me take the pictures above in their yard. They ship nationwide so you can call them from anywhere.

Here’s a simple sketchcast from WoodScience (became Lumber Talk) on how to build a wood bulkhead.