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By Chris | November 11, 2013 - 12:17 pm - Posted in Specs & Data, Treated Wood

There’s a common question that gets batted around. The answer is simple but the reason is usually not explained well. Feel free to add your 2 cents, too, if you happen to be a chemist or treated wood pro.

Can you burn treated wood? Well, yes. You should know it is illegal in all 50 states to do so.

SHOULD You Burn Pressure Treated Wood?

NO. You should not burn pressure treated wood — ever. Again, it is illegal in all 50 states to burn pressure treated wood.

Why You SHOULD NOT Burn Treated Wood?

First, it’s illegal. If by some chance it is not illegal where you are, it probably should be. Second, the metal left in the ash is probably harmful to you or the environment in one way or another. For the purpose of this post, we’ll focus on 3 chemicals commonly used to pressure treat wood.

  • CCA — Chromated Copper Arsenate — only used for commercial and marine applications now
  • MCQ — Micronized Copper Quaternary — used for residential and commercial
  • CA — Copper Azole — use for residential and commercial

The primary ingredients in these pressure treated wood chemicals are metals — copper, chromium, and arsenate (a form of arsenic, in case you were wondering). When treated wood is burned, the metals remain in the ash. Inhaling the smoke would be bad for you, too, but the main danger comes from the concentrated metals left in the ash.

All three metals are toxic to some degree. Arsenic is the worst, by far. According to this discussion string, the ash left from burning CCA treated wood is toxic enough to kill cows and deer.

Copper and chromium are also toxic but not so severely poisonous as arsenic. The human body needs some copper to function properly but too much lead to a host of issues from diarrhea and vomiting to liver failure and more. Here is a list of possible reactions to copper toxicity and some more here. Chromium poisoning appears to be pretty terrible, too.

Chromium poisoning is very rare but it is possible. Chromium is an essential nutrient in the human body and helps with how insulin regulates blood sugar levels. Too much can cause rashes, renal failure, and more.

There you have it. The short answer is DON’T BURN TREATED WOOD but the readers of LumberTalk tend to like more complete info so there you go. Here’s a post where someone posts the question about why it’s so bad to burn treated wood. The responses are aggravating because no one answers his question and only tells him to trust in knowing that it’s dangerous. You might actually feel a little sorry for “tgm1024.”

By Chris | October 6, 2008 - 9:11 pm - Posted in Specs & Data

Actual lumber sizes are a pain to keep up with. I find myself having to refer to charts from time time and I deal with lumber all the time. I get asked about actual versus nominal lumber sizes on a regular basis. Most people know that a 2×4 is actually 1.5″x3.5″ but the measurements are different for the large boards like 2×8’s and 2×12’s.

Actually, the more common term is “lumber dimensions“, which I have written about before, but people often ask about “lumber sizes” so that is how I am explaining it here. Your choice of search terms is probably why you found this article.

Lumber Sizes

Here is a chart to clear up the confusion about 1x, 2x, and 4x nominal lumber sizes versus actual lumber sizes including the equivalent metric lumber sizes. This lumber sizes chart applies to treated and untreated pine construction grade lumber.

lumber sizes chart - actual dimensions versus nominal dimensions

This chart applies to the lumber sizes of “quarter” measurements. The nominal lumber sizes are said as “five-quarter by four” or “six-quarter by six” etc. These are not all that common but you can usually find “five-quarter” decking whose actual dimension is 1″x5.5″. You might hear the 1/4 sizes used more commonly among more mature – no, more experienced – builders and lumbermen.

five quarter lumber sizes - lumber dimensions

Timber Sizes

Lumber cut 5 inches or thicker is generally classified as timbers. Timbers are usually “rough cut” to actual sizes. In other words, what you see is what you get. A 6×6 is 6″x6″, a 10×10 is 10″x10″ and so forth. When you buy timbers in smooth, or S4S (Smooth 4 Sides) the sizes are usually 1/2″ smaller. In this case, a 6×6 would be 5.5″x5.5″.

Post Sizes

Round stock sizes can get a little complicated but we will keep it as simple as possible here. A thorough discussion including large poles requires getting into the differences between poles and pilings and classes of utility poles and what you are using them for and it goes on and on so…so for the purpose of this article, I will stick to small post sizes.

Small posts are usually measured by the top size (the little end). So, if you want a 4″ top x 8′ long fence post, you would ask for a “four inch – eight” post. The line between post sizes and poles is a fuzzy one but after about ten or twelve feet long, whatever it is that you want usually becomes a pole. If you are using it in water to support a structure it is probably a piling, which is used upside down and measured by the butt (the big end)… and see how it easy it is to get complicated when discussing poles?

If you want square posts make sure you are clear about that when you ask for “posts” as “posts” are usually considered to be round.

Lumber Sizes Questions?

If you have any questions about lumber sizes, let me know with a comment.

The life span of your treated posts posts matters. Before spending thousands, or tens of thousands, of dollars on a fence it is nice to have a better idea of how long you can expect your investment to last.

So, to answer the question: How long will my treated posts last?

According to the Southern Pine Council you can expect properly treated posts to last many decades. They site a study by USDA Forest Service’s Forest Products Laboratory saying:

Test stakes of treated wood have been buried in the ground at various locations, stretching from the Mississippi Delta to the Canadian border. Data analysis indicates that CCA-treated Southern Pine stakes in place since 1938 have shown no failures at chemical retention levels of 0.29 pounds of preservative per cubic foot of wood, or higher.

Most treated posts are treated to a retention of .40 but you should always ask – just to be safe.

Here’s a great pdf from the USDA with expected life spans for various species of treated posts including a comparison of the life spans of treated and untreated posts (see page two).

If you want a guarantee that your posts will last you can get treated posts coated at the ground line from American Pole and Timber. I mentioned these posts before in How to Build a Fence that Lasts because I have seen them up close and they are tough. They claim that posts coated at the ground line with their poly coating will last fifty years.? In reality, the posts should last 150 years because the ground line is the source of infestations and the place where decay begins.? If that is protected, you don’t have much else to worry about.

The bottom line is that the life span of properly treated posts should be at least 20 years and can be easily extended to 50+ when installed and used in normal conditions (not in water or along the coast, for instance) .? If you choose the right materials, your grandchildren won’t even have to deal with building another fence.

By Chris | April 23, 2008 - 3:33 pm - Posted in Poles, Posts, Pilings, Specs & Data, Structural Components

I am regularly asked about pole prices – everything from prices per size to freight costs and installation, etc. The object of this video and chart is to briefly explain the basic pole prices relative to length, the most commonly discussed characteristic of the pole.

Poles come in numerous sizes, species, grades, and treatment levels. Each of those factors affects price. The biggest factor affecting the delivered price of a pole (treated or untreated) is sizemostly length – and that can be broken into two main reasons.

  1. Supply: Trees take a long time to grow and BIG trees are getting scarce.
  2. Freight: Permits and special equipment are probably required for long lengths.

In fact, if you order an 80′ long pole today it is likely the tree you will receive is still in the forest today. Crazy, huh?


The chart does not appear clearly in the video. Here it is (below) so you can get a better look.

Don’t use this chart to bid your next project or anything. I simply wanted to make the point that around the 50′ length mark, the pole prices curve turns sharply north. Also notice that the incremental pole prices on the left get larger as well. Yes, it is certainly possible that you might pay $5,000 (delivered) for a 90′ pole. Don’t even ask about poles beyond 100′.

Pole Prices Chart -Prices versus Length

You should always design based on the needs of the structure (as opposed to what materials are cheapest) but “value engineering” is always important to keep budgets in check and projects affordable. With that, if you are building a structure that requires poles longer than about 50 feet, you might consider brainstorming ideas to design the structure so it can use shorter, less expensive, poles.

Basic Take Away about Pole Prices (in a rhyme): Under 20 feet, poles are cheap, beyond fifty, prices are ‘iffy. 🙂

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.