Framing with poles

One of the most challenging strategies to our shipwreck building research was to develop a roofing system that could either grow on the island or be simple, lightweight, and easy to import. Our first thought, of course, was bamboo with thatch. Bamboo is easy to grow in the tropics and sub tropics, is now being grown commercially on Maui and the big island, and Bamboo Technologies, headquartered on Maui, has won code approval for one species, bambusa stenostachya, grown in Southeast Asia.

Bamboo for construction has gained a lot of momentum in the past decade, thanks in large part to the work of architect and builder Simon Velez. I was pretty certain bamboo poles for roof structure, in combination with rammed earth walls, would be two key components on our ultimate building materials pallet.

Bamboo Technologies produces pre-cut kit homes using plywood and bamboo panels for both walls and roofs. I was hoping to get away from the plywood and use braced poles for the roof framing with a separate, non-structural roof cover. I still wasn't sure what the roof cover would be. I didn't think thatch would have the durability we were after; plus it's a little too much of a stretch even for my unconventional approach. Clearly we had some things to learn and experiments to conduct before we were ready for bamboo roofing.

As a starter, and to make obtaining our permit a little easier, we decided to introduce the building department to stabilized earth first and move into bamboo later. But, wanting to get some experience working with round structural members rather than sawn wood, we decided to use galvanized steel poles. You can buy them in bulk from fencing supply companies, and they are relatively inexpensive. We designed the roof with trusses and bolted connections similar to those we had seen in Simon Velez's book. It's all very light-weight and can go up quickly.

We had cut and drilled the members for the trusses before loading them in the shipping container. The first of our pavilions was going to have 6" thick walls of hand-thrown earth rather than traditional rammed earth, so we set two rows of poles in the foundation as we were pouring the slab to receive the trusses. If we had built 12" thick rammed earth walls, we could have skipped the poles, but since we didn't know how often it rained, we thought it would be best if we put a roof up quickly and then worked under the roof to build the earth walls. As you'll see in later posts, we did switch to traditional rammed earth when we found out that most of the time the rains are short and sweet.

As you can see in the photos included with this post, the roof framing did go up quickly, thanks to all the help from our friends who flew over the join the first of many work parties.