Treatment for Bamboo Poles Buried in Soil

I have a question regarding bamboo treatment. I want to use bamboo poles as structural elements in my ranch but we have water sprinklers to keep certain crops fresh all year. How can we treat the poles in order to keep it in use at least 6 years buried in soil inside the wet ground? Poles will be buried 3 ft in the ground.

Would the bamboo lose strength with time? How do I preserve and extend the lifespan of the bamboo? What would be the lifespan of the bamboo after the preservative treatment? I was thinking to use busan 1009, do you recommend it? Thanks for your comments.

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⭐ Best Answer:

Generally speaking it is not recommended to use bamboo buried in soil for structural purposes. You should use chemicals to extend the lifespan of bamboo buried in soil, but just as most timber, bamboo will eventually deteriorate even if chemically treated.

I have no experience with busan 1009 but what we use to protect bamboo poles in ground contact is tar. Tar or creosote isn't exactly an eco-friendly product, but it is cheap and does provide excellent protection. I recently dug out some bamboo fence posts treated with tar, and they were still intact after 10 years.

The best way though is to chemically preserve the bamboo poles and to design a structure where the bamboo poles don't touch the soil directly. A concrete foot or large rock for example would work great.

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Fire Resistant Protection for Structural Bamboo

I have a question for my research, what would be the best preservation technique to use on structural bamboo? It needs to be fire resistant too. Will a boric acid-borax solution suffice? Or would an additional clear external intumescent coating help? What do you guys think? Thanks in advance. I appreciate the information you guys put here Guadua Bamboo.

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⭐ Best Answer:

Yes, boron is fire retardant but for even more protection you could use the following formula: boric acid / copper sulphate / zinc chloride / sodium dichromate : ratio 3:1:5:6 Recommended concentration is 25% for indoor and outdoor use.

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Installing free standing bamboo posts in or above the ground

I have been working with bamboo for around 20 years. I've built numerous structures for Quindembo Bamboo Nursery on the Big Island of Hawaii. Their nursery used to be located in a drier part of the island but now they have moved north where it rains more often.

Before when I set posts I coated them with a waterproof substance such as Henry's roofing tar and set them in the ground. This technique has proven to be effective lasting 20 years and counting but now that the nursery is in a rainy climate, the ground is soft soil and perpetually moist and I'm dubious about setting bamboo in this, even with a waterproof membrane.

I just finished building a cool little outdoor bathroom where i used polycarbonate roofing as wall panels sandwiched in between bamboo halves and capped with bamboo. This worked out well but it was on a deck. I fastened the bamboo to the deck by making wooden inserts and screwing them to the deck first then placing the posts on top.

This next project I have is a couple of small fences and I'm hoping to make it more affordable. People think that bamboo is going to be cheap but it's actually quite labor intensive with everything being custom fitted as well as the harvesting, trimming and finishing. Anyway, I was thinking of driving steel fence stakes into the ground and filling the culms with mortar mix and acrylic additive and setting them over the steel stakes so that the bamboo is off the ground six inches or so.

Do you have any ideas about setting free standing posts in or above the ground that's quick and easy? Are you laughing?

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⭐ Best Answer:

You can try used plastic bottles instead. Make sure to leave them at least 3 to 4 inches above the ground. Place some mortar inside the bottle so that it will hold the pole upright. Cut the top of the pole as close as possible to the node so it cannot collect rain water (or it may rot). If you like to do some additional work, try to burn/stain the outside of the poles with a butane torch, it won't change the structural properties.

How to Join a Bamboo Pyramid?

I am using guadua as the corner posts for a pyramid. Any suggestions as to how to join these at the top would be greatly appreciated. The lengths of the posts will be 8.5m, the pyramid base 9m x 9m. The height at the apex 6.5m. We need to get the joint exactly right to ensure the energetics of the structure are correct. Suggestions as to how to raise the posts are also appreciated.

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⭐ Best Answer:

Here is my advice:

Cut two pole ends in the right angle so that they have a flat surface where they touch. Cut it about 10 cm above a node in the pole to prevent it from splitting. Find a piece of bamboo that is just oversize to fit inside the bamboo poles. Scrape off the outside layer just until you can slide it in but with a tight fit. Insert them into both ends and cut them just above the node flush with the surface you cut at the large pole end. Take a piece of strong wood large enough to cover the (oval) pole ends about 2-3 cm thick. Trim of the excess wood sticking out. Place THICK dowels in the wood sticking out on BOTH ends. Mark the holes on the bamboo pole ends and drill them to the size of the dowels. Don't drill too deep! Put a bucket load of (waterproof) glue on both ends of the wood, on the dowels, and the pole ends. (If you don't find any glue in your underpants a week later, you did not apply enough glue.) Press both ends together and keep the PRESSED together until the glue is DRY. As in fully cured.

Provide a proper foundation for the poles that protects it from ground moisture. Either a concrete foot or a steel pipe in a bedding of gravel might do the trick. Don’t be cheap on the foundation. Unless you want big hospital bills from collapsing roofs etc. For this size, depending on weight of cladding, expected wind loads and snowfall I would say you need AT LEAST 1 m³ for every pole.

Good luck!

Bamboo Architecture Unboxed

By Stamm, Jorg, Vahanvati, Munir

Shaping Bamboo as it Grows

Have you ever heard of, or experimented with “molding” guadua bamboo as it grows, to end up with a finished pole that has the exact shape you need?

I am researching these interesting helix shapes as Zome structures, and I realized that bamboo structural poles formed into the complicated spiral shapes needed would be perfect. Here is the link to info about it: Helix Zome.

All the necessary spiral poles would be exact copies of each other, so some sort of shape-retainer of the bamboo while it is growing would make for a super strong and very beautiful zome structure. If you have ever heard of anyone bending guadua bamboo as it grows, I would love to hear about it.

BTW you have got one excellent website! Thank you very much for all of your work on it. The amount and quality of content is superb.

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⭐ Best Answer:

Shaping or bending bamboo as it grows is definitely possible although “exact” copies of a certain shape would be very difficult in my opinion. Brian Erickson in Costa Rica grows twisted bamboo stems to built exclusive bamboo furniture. The video below gives an idea of how he does this.

The attached picture demonstrates another example of a “twisted Guadua bamboo forest” in Colombia. Again it is important to note that this isn't the natural growing behavior of Guadua angustifolia. It is artificially grown in these shapes and turns, usually by guiding the young bamboo shoots through car tires or suspending ropes.

Twisted Guadua bamboo forest

The picture examples you provided however seem to use bamboo slats, which is the most common way in dome structures. Bamboo slats are very flexible and therefore easier to work with.

Submerging Bamboo in Sea Water

I've read that submerging bamboo in sea water is another traditional treatment of bamboo. How long-lasting will the bamboo be using this treatment?

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⭐ Best Answer:

Let the poles or the splits dry thoroughly under the sun. Then soak them in the sea for 2 months. The dry poles and splits easily absorb all the salt of the sea. This sea-water treatment gives the bamboos at least 50 years of protection from termites, borers and fungi. It’s widely used in Asia and also used for wood treatment. Very safe and natural, very effective and cheap and truly long-lasting. Good luck.

Curing Bamboo Posts for Vineyards

I have read your article about poles and the durability of bamboo but do you think it would be feasible to treat bamboo for use as posts in vineyards? I live in the Margaret river wine growing region of western Australia where thousands of CCA treated pine posts are used.

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⭐ Best Answer:

If treated with a fixating chemical mix such as CCA or CCB, yes. In Costa Rica banana plantations have traditionally been growing bamboo as well, in order to use the bamboo poles as plants support sticks for the banana plants. These bamboo props aren't treated and are replaced every 2 years. Untreated bamboo support sticks are also used in various vegetable crops.

Is there a minimum life span required for vineyard posts? If not, untreated poles might be the cheapest solution, especially if you grow them yourself.

Safe and Ecological Preservation of Bamboo

I am designing a house to suite the emerging middle class in Ghana, looking to understand more about bamboo preservation techniques that offer excellent protection against rot and insects.

From what I’ve read thusfar, it seems that chemical treatments will be most effective, and I am searching for a solution that will be environmentally safe, to both nature and the inhabitants. Any recommendations, especially with regards to being situated in southern Ghana (a hot and humid climate with two distinct rainy seasons each year)?

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⭐ Best Answer:

One of the most effective ways to cure bamboo is by mixing boric acid with borax (you can buy this as a pre-mixed solution under the name: Timbor) in a ratio of 1:1.5 with a concentration of 5%. In other words mix 2kg of boric acid with 3kg of borax in 100 liters of water. Perforate the diaphragms (in case of round poles) and submerge them in the water-boron mix for 4-5 days. The vertical soak diffusion is an alternative method for submerging bamboo in tanks.

Boron is basically a salt, it protects the bamboo from fungus and insect attacks. It is however a non-fixing preservative, which means the boron will leach out in direct contact with rain. This you will have to keep in mind when designing the house.

In regards to its toxicity, boric acid naturally occurs in the environment. It can be found in soil, water, and plants. Boric acid dissolves in water and can move with water through the soil. Under certain soil conditions it can reach ground water. However, its mobility in soil depends on pH and the presence of some metals. Boric acid can also be taken up from the soil by plants. It moves through plants into their leaves. Once there, it generally becomes stuck and does not move into the fruit. Plants need boron, a major component of boric acid, to grow. However, too much boron can be toxic to plants affecting their growth. Citrus, stone fruits, and nut trees are most sensitive to boron.

Boric acid does not emit vapors into the atmosphere. Particles that get into the air do not break down. They settle to the ground or are removed by rain.

Boric acid is practically non-toxic to birds. It is slightly toxic to practically non-toxic to freshwater fish. Boric acid is practically non-toxic to frogs and toads and aquatic life, such as waterfleas. The U.S. EPA concluded that boric acid is relatively nontoxic to bees.

Source: National Pesticide Information Center

Curing Bamboo Immediately after Harvest

What's the notion of this harvesting technique? Cut green culms and place them in a 5 gal. bucket with 3 gals. of a 10 % solution of Timbor (a borax / boric acid solution) in water. This happens in the grove for a month.

Shouldn't the boric solution be drawn up the culm by capillary action yielding a cured culm in a month? After a month remove the culms to finish drying vertically in a shady spot for another month. What do you think?

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⭐ Best Answer:

What you’re describing is a soak-and-draw treatment, it’s basically using the fresh culm’s own capillary action to pull the borax/boric acid solution up and replace the sugars that bugs love. A month standing in the bucket is usually more than enough (even 1–2 weeks should do it), then drying vertically in the shade is the right call to avoid cracks.

Just keep in mind uptake isn’t always even, especially on thicker culms, and older poles (3–5 yrs) will be more durable. For max protection, full soak or sap displacement works better, but this setup can give you serviceable, bug-resistant bamboo (especially for small- to medium-diameter poles).

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