Preservation of Bamboo
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Q: I am having a really hard time finding answers and instruction how to dry out the bamboo that is growing on my land. I would love to be able to build some of the following: trellis, small furniture, decortive walling, plant holders, a bar for my pool deck, etc.

A: Some basic principles of harvesting and curing are:    

1. Harvest only poles that are mature- at least 5 years old.    

2. Store in an open air rack -in the shade. You might want to rotate occasionally.    

3. Cure for a few months, until completely dry, before use.    

4. Stand cured bamboo, those that die and dried out while still in the stand, can be used immediately.    

5. A light scrubbing with a dish scrubber will bring back the luster of the skin, and remove any lichens, etc.    

6. Bamboo will split, especially the larger diameter pieces. You can wrap wire around the ends to prevent this, or, pre-split the bamboo to relieve the stress and prevent further splitting.    

7. You can oil or wax the bamboo for a nice sheen, and it is good for protection from the elements.

Q: I live in Sri Lanka and nobody is building with bamboo here which is a shame. My understanding is that bamboo likes shade, no rain etc. Here it is always raining and the sun is scorching one minute and then not !! OK So I still wanna try and build a bamboo treehouse which will be shaded in a jack tree. So we cut the bamboo and the pieces are 30ft in length...what do we do then? Do we need to boil them? If so, in salt water or chemicals, and for how long? Do we then leave it for some time? I was thinking of building a 12 ft long boiling half cylinder welded oil cans cut in half !! Once these are cured what further treatments can we put on the bamboo to prevent rain and sun damage, temperature fluctuations etc.

A: Make sure you cut older bamboo (over 5 years since sprouting)- it needs to lignify for strength and durability. Also, what is the species? Some species are better than others- starch content being the biggest factor (more starch-more attractive to bugs-termites, bamboo beetle.    

The best environmentally benign treatment is with borax solution- either pressure injected into the xylem and phloem, or taken up naturally with a bucket under a newly cut bamboo (left standing-in place)     Keep the bamboo out of the direct sun and rain as much as possible (borax is water soluble)- big overhang (the hooch design is good for this (http://www.tropical-treehouse.com ) Also, keep bamboo away from direct contact with soil - route for bugs - and moisture retention. Bamboo should be cured (dried, in the shade) for a while (months) before use, or use only stand cured bamboo (dead, and dried naturally). Or, if exposed and airy construction design, you may use green bamboo (still not recommended). I have heard of salt-water soaking as a treatment also. But, it does leach out, and salt attracts moisture.

Q: I would like to construct a bamboo screen to enclose the under-floor area of a newly built pole-house in Sydney, Australia. The area is bushfire prone and subject to white-ant/ termite problems. I intend to harvest about 60 culms and cure by standing for 3 weeks then immersing in salt water for anothter 3 weeks. I would then like to longitudinally split the culms for ease of mounting and weight saving, then gal-wire the material onto 2m high sections of gal-steel grid (ala concrete reinforcement mesh) If the mechanics of the above sound ok, I wondered about the flamability of the product when cured, and wether the cured material is tempting to termites. We have the house erected on gal-steel poles and I want to avoid offering the little buggers an easy route of ingress. Any advice will be greatly appreciated.

A: I will say you aussies got your act together. The plan sounds good. I would recommend that the culms be split first, before soaking, so that the salt water can penetrate the meat of the culms better. Salt preservation works. I assume you have low rainfall and/or a large overhang- best for keeping the salt from leaching out. Also, direct sun on bamboo will dry it.crack it, and grey it. The bamboo should not come in contact with the earth. Moisture will rot it, and, it is a nice unseen route for those buggers. If the bamboo starts, say, 6 inches above grade, any ants/termites traveling upward can be seen, and dealt with. Also, leave a gap where the bamboo meets the house as well- another visual window. Also, a cheap preservative, in addition to salt treatment, is used engine oi. I've seen it used, though I've not used this technique. It might keep the bamboo from drying out a bit. Bamboo has a high flash point- the temperature where it burst into flame. But, once burning, burns intensely. Salt treatment does reduce the flammability, though not completely.

Q: We have a good overhang so moisture is not so much of an issue, but we have really strong sun in the early part of the day. Would the culms be less susceptible to cracking and drying out if left un-split? There are pre-fab fencing products (gal wired bleached bamboo) that I am trying to emulate in a way. Will these crack too or is there a step I'm missing.

A: Actually, splitting the bamboo is the best thing you can do to prevent splitting. The eventual differential shrinkage that occurs with the drying process is inconsequential when the culms are already split. The splits can change their shape without the splitting if they were whole culms. Even pre-split culms may split more under direct sun, however. Love the splits- no problem!

Q: Do you know of any bamboo product for exterior siding? I live in a cool, rainy climate in Portland, OR.

A: Bamboo needs to be treated with severe chemicals before it is ever ready for exterior siding. Bamboo likes it in the shade, away from rain, away from direct sun, away from moisture. Cedar, maybe.

Q: I purchased a 5" diameter 10' pole of Moso bamboo grown in China. It is slighty green shaded but mostly yellow so it is fairly freshly cut. The smaller end was split but I'm using 3' of the 5" end still entact. What can I do to best maintain pole and prevent splitting? I am using it indoors and reside in subtropical southern California.

A: The bamboo will need to dry out, but slowly. Even so, the cracks will progress unless measures are taken. Cutting the remaining, unsplit bamboo from the split end will stop the progression. Also, you could wrap a few turns of wire around the ends to prevent a split from developing. A slow curing is best. Keep it in the shade, away from extreme changes in temperature. Allow air around it, store it vertical or well supported horizontally.

Q: Do you have to dry out the bamboo before building something such as a tiki bar?

A: It is always best to dry out bamboo before using...slowly, uniformly, to prevent cracking. Even then the bamboo may crack, being exposed to whatever conditions. If you use green bamboo, use it as splits; it will not split more, and it is easier to bend. As it dries out, it will relax a bit to the contortion it is fitted. Depending on where you live, the bamboo may be more susceptible to insects if used green (the tropics).