why pressure treated lumber is bad and how to find alternatives to its use

Pressure treated lumber is right up there with the use of toxic pesticides in my mind even though the newer stuff has no arsenate.

Today, pressure-treated lumber is treated with a range of inorganic chemicals rather than arsenate. Other common chemicals used are Alkaline Copper Quaternary (ACQ), Copper Azole (CA), Sodium Borate (SBX), and Micronized Copper Quaternary (MCQ).

I know some folks here feel they have no choice but to use it in certain applications.

I would like to explore alternatives to it's use in this thread along with why it's such a bad choice for the world's health and not at all an appropriate choice for permaculture.

https://en.wikipedia.org/wiki/Wood_preservation

I've always viewed this toxic material as something I don't want to add to my home and surroundings...that makes it a simple choice then to look at alternatives.

I think looking at pressure treated lumber as an option allows folks to avoid proper building techniques.

I'm hoping maybe this can be a thread where there are enough alternatives given that this material will stop being suggested here at permies, where we are talking about organic and beyond.....

Here are a few threads in the natural building forum with alternatives to toxins.  Also, check out the 'similar threads' list at the bottom of each of these topics for more....

https://permies.com/t/42996/Wood-Preservatives

https://permies.com/t/16450/post-beams-stone-foundations-preventing

https://permies.com/t/25702/treat-wood-construction-materials

https://permies.com/t/47413/Designing-pole-building-easy-replace

Shou Sugi Ban, a method, suggested by a new member who can't post in the ciderpress yet thanks Matt!

https://permies.com/t/37505/Yakisugi-grilled-cedar-Charring-Wood

https://permies.com/t/22394/charring-effective-treatment-ground-preservation

https://permies.com/t/46343/Permie-friendly-wood-preservative

I thought this was an interesting article http://www.epa.state.il.us/water/conservation/lake-notes/pressure-treated-wood.pdf

One thing that caught my eye was that 'some manufacturers guarantee their PT wood for forty years or longer'.  Even considering the 'or longer' part, that sounds like a temporary fix to me, when some natural building methods can last for centuries and don't leach and leave behind a chemical residue for their lifetime and beyond.

I would be curious to hear specifically why people think (modern!) pressure treated lumber is bad, and in what context. Just because something has a chemical makeup we're not familiar with does not make it bad. Everything I have learned talking to foresters and other people in the lumber industry is that the old style CCA wood was really bad, but the modern stuff will only leach copper into soils over time and contains no known carcinogens or toxic chemicals. That does not mean they are right, but I'd love to hear a cohesive argument past "it's bad" as that's not really a great way to convince engineers and contractors.

I use PT wood, not often, but I do. I do it because I value the lives of my friends. These timbers are in contact with the soil, making it highly susceptible to rot and insect damage — damage not obvious to the eye until failure. Since the wood is in contact with the soil, it's often a part of the foundation of structures, and that's not an area I'm willing to leave as my weakest link when building. I have seen far too many houses and decks collapse in very bad ways because people did not take dry rot / termites seriously. This is especially relevant to my climate, where heavy snow load can come in unexpected and pile up quick.

I have seen many "natural building" techniques in effect that terrify me. People will often build a structure, take a look at how it's holding up the next year, and declare it a success. I have watched people follow Mike Oehler's advice about PSP, but neglect to follow his advice about replacing structural posts every few years. Most of these techniques are great for fence posts. It can rot away, fall down, and maybe a cow gets loose. But I would never use that kind of technique for a pylon holding up a cabin under 12ft of snow.

That being said, the best way to preserve wood is to keep it dry. Choose structural techniques that do not require you set timbers into the soil. Build a foundation out of boulders, concrete, cinderblocks, etc. Drill or set metal anchors into this foundation and attach your timbers. You can also build skiddable structures that you can jack up when the skids rot away.

Judith: Of note, that paper was from 2001 when CCA was still widely used (the chemicals mentioned in the paper are the ones used in CCA products). In 2003, arsenic-based preservatives were outlawed in America and manufacturers have since moved to MCA/MCQ, which has a radically different chemical composition.

Kyle Neath wrote:Judith: Of note, that paper was from 2001 when CCA was still widely used (the chemicals mentioned in the paper are the ones used in CCA products). In 2003, arsenic-based preservatives were outlawed in America and manufacturers have since moved to MCA/MCQ, which has a radically different chemical composition.

Hi Kyle...this is exactly the conversation I was hoping for.  I do know that arsenic treated lumber hasn't been used for a few years.  I think it is still being processed and used for certain industrial building applications though, just not for home use by the permies.

I am reading more on the more modern treatment used and have found some reference in this link http://swst.org/wp/meetings/AM06/freeman.pdf

I don't know the long term effect of what leaches from this treatment and neither does the industry, of course, since it has only been in use for fifteen years or so.  So many things have been promoted as 'safe' in the beginning and then decades later the real story emerges.

I can't find any mention that modern treated lumber is accepted by organic standards...for me that's enough reason to avoid and I realize for others that might be meaningless.

If someone knows of a natural way of treating wood for underground use, like Mike's underground houses, that is proven to last even 20 years, I would be ecstatic.  It would be great to have nice seasoned black locust that was large enough and straight enough to support a structure, but I don't.

when the industry stopped using chromated copper arsenate (CCA) for residential use. It's a widely used preservative with a track record of decay resistance going back to when it was introduced in the mid-1940s. Health concerns about the chemical led the wood treatment industry to stop using it for residential purposes in 2003, but it's so effective that it's still used for telephone poles, docks, boardwalks, and large-scale commercial projects.


Today, pressure-treated lumber is treated with a range of inorganic chemicals rather than arsenate. Other common chemicals used are Alkaline Copper Quaternary (ACQ), Copper Azole (CA), Sodium Borate (SBX), and Micronized Copper Quaternary (MCQ). These newer types of treated woods may be less toxic, but they also contain higher levels of copper, so they're much more corrosive than the old CCA-treated lumber. 



Many pressure-treated lumber manufacturers recommend using only stainless steel or hot-dipped galvanized nails, screws, bolts, anchors, and connectors when working with the material. And because these new wood treatments are especially corrosive to aluminum, it's best to use vinyl or copper flashing, or to wrap the wood in a protective rubberized membrane.

Here are a few extra tips to keep in mind when working with pressure-treated lumber:

•Wear gloves when handling treated wood, and wash up thoroughly before eating or drinking.

•Always wear safety goggles and a dust mask when cutting, drilling, or sanding.

•Cut treated wood outdoors, not in an enclosed space. Never burn treated wood.

http://www.popularmechanics.com/home/outdoor-projects/how-to/a3103/your-guide-to-working-with-pressure-treated-lumber-15655848/

http://www.deckmagazine.com/design-construction/the-new-preservatives_o

Not only do ACQ and CA have two to three times as much copper as CCA, the form of copper they contain is more chemically active. According to Dr. Jun Zhang, director of Osmose’s (800/585-5161, osmosewood.com) Buffalo Technical Center, the copper in CCA binds with the wood, providing relatively few copper ions (the reactive form of copper). The formulation of ACQ and CA, on the other hand, allows for more free copper ions. And unlike CCA, ACQ and CA don’t contain chromium, which inhibits corrosion.

Todd Parr wrote:If someone knows of a natural way of treating wood for underground use, like Mike's underground houses, that is proven to last even 20 years, I would be ecstatic.  It would be great to have nice seasoned black locust that was large enough and straight enough to support a structure, but I don't.

Pressure treated wood isn't going to last anywhere near forever in the ground either though.  
It might buy a few more years and then what?

I think some of the topic links in my posts above cover possibilities for building foundations to last without toxins.

Judith Browning wrote:

Todd Parr wrote:If someone knows of a natural way of treating wood for underground use, like Mike's underground houses, that is proven to last even 20 years, I would be ecstatic.  It would be great to have nice seasoned black locust that was large enough and straight enough to support a structure, but I don't.

Pressure treated wood isn't going to last anywhere near forever in the ground either though.  
It might buy a few more years and then what?

I think some of the topic links in my posts above cover possibilities for building foundations to last without toxins.

I didn't mean to suggest it would, just that I haven't seen any natural treatment that will last underground any length of time.

Todd Parr wrote:

Judith Browning wrote:

Todd Parr wrote:If someone knows of a natural way of treating wood for underground use, like Mike's underground houses, that is proven to last even 20 years, I would be ecstatic.  It would be great to have nice seasoned black locust that was large enough and straight enough to support a structure, but I don't.

Pressure treated wood isn't going to last anywhere near forever in the ground either though.  
It might buy a few more years and then what?

I think some of the topic links in my posts above cover possibilities for building foundations to last without toxins.

I didn't mean to suggest it would, just that I haven't seen any natural treatment that will last underground any length of time.

got it!  I get a little one track minded  

I am fortunate in that I have lived here for 43 years and know the history of this farm before that. One thing we use here a lot, simply because we have a lot of it, and because it has no commercial forestry value, is White Cedar. It is never listed as a really long term wood, but we use it because we have it and it gives us longevity on projects.

In another thread I talked about fence posts and in that one I give it a service life of 15 years. Not great, half the life of pressure treated fence posts. But that is partly because a fence post is only a few inches in diameter, add a bit of rot and an animal pushing on it (whether within or a predator from without...moose REALLY play havoc on my sheep fence) snap them after 15 years. But for structural posts, or sills in a house where there is some semblance of protection, I give them 20-25 years. At my age, that does not really work. That means when I am 68..too old to want to crawl underneath and jack and raise buildings up to replace sills, I would have to. Far better to use something that lasts a bit longer, but fence posts, those are easy to replace. However for a 60 year old...a 25 year sill life is fine, it will most likely outlive them.

I move a lot of buildings and naturally do so on skids. I use cedar when I can mostly because once they are towed into place I can leave them on their foundations without worry for the next 25 years. For an outbuilding, that is just fine.

Here is a fence post that I happen to know the history of. It is of white cedar and installed in the mid 1960's. It has no service life left, but I bet my Grandfather never thought it would still be standing 51 years later.

Yeah, I don't see a reason to use wood underground. It seems like we're trying to make a natural thing do something it doesn't naturally do.

I would use masonry pilings to sit posts on. In terms of cladding and roofing, I would use either naturally rot-resistant woods, like cedar or black locust, or I would Shou Sugi Ban them. I don't know if Shou Sugi Ban can be applied to a whole structural member, but that, too, might be an option.

-CK

A very interesting discusion.

A few comments - many old cities are build on wood foundations. Some go back to the early middle ages. Wood seems to do fine underground when fully submerged in water (no oxygen), wet peaty soil (low pH and no oxygen) or water naturraly rich in some heavy metals (low pH, low oxygen and As, Cd, Pb, etc....). Conclusion it can be done under special circumstances but there are environmental problems associated with that.

In the Vosges Mountains in France i once visited an old silver mine that was partially flooded. In the water you could see well preserved wooden ladders from before the 1800's. If memory serves the ore was sulfidic. The weathering ore set free arsenic and other metals.

There are wood preservatives that are free of heavy metals but the used organic fungicides or boric acid have an unknown or badly understood behaviour in the soil (unless you are happy to take just the word of the producer/developper of the stuff). I once initiated a soil testing programm in a lumberyard where they had soaked wood in preservatives of all kinds. The results were difficult to interpret but i came away with the general impression that there is hardly any reliable science - read toxicity, biodegradation and risk assesment - done on the behaviour of wood preservatives in the soil and groundwater.

Those products are marketed in Europe as wood preservatives under names as basilit etc.... Since the name basilit is introduced, the composition of the stuff has changed several times in accordance with EU-law.

Some of these fungicides are used in food plant protection - so human toxicity is definetely lower than heavy metal based stuff BUT their effect on soil fungi..... is probably not good.


I have a lot of articles in my private database. I'll try to add them here and in a following message. Texts coming from the EU may be in Dutch, German or English. Some texts are available in translation on EU-websites. Others are safety sheets that can be found in several languages (including, Englisch, German, French, ....) with national autorities in EU-memberstates.

Part 2

Next bunch of articles - sorry that it is not superorganized. Time is lacking to go for an apple.

Propicanozole and cypermethrin are supposed to be used as woord preservatives for wood not in permanent contact with soil.


Texts with FOREGS in the filename are produced by a geochemical mapping initiative in Europe. For those who want access to advanced material - similar geochemical mapping is available in many parts of the US and Canada. If notting else it gives you an idea of what concentrations of selected chemicals are possible under natural circumstances.

Part 3

Some of these texts are more than a bit complicated but the list of references at the end is sometimes very usefull. If you have acces to a scientific library (without having to pay big bucks to read the really good stuff) you can use these references to find more recent material.