Sustainable & Cost-Effective Building Materials in Nepal

Nepali house construction traditionally consists of locally sourced materials – bamboo, wood, mud plaster, hand-mixed concrete, and corrugated metal. Not only are these materials readily accessible, they also allow people to build with resources found on their property for free or sourced locally for a small fee. (Many of the people in the area live on less than $1/day so they have learned to be very resourceful.)

Bamboo, as a building material, is very versatile. It rivals steel in tensile strength and is comparable to concrete, brick or wood in compression. It can be used as a structural member or for aesthetic purposes.  For these reasons and the fact that it grows abundantly in the region, it’s easy to see why bamboo is such a popular material.

Building Bamboo Houses in Nepal

During the two-week trip, our team of volunteers (15 of us from various countries) helped two low-income families build their bamboo houses. Houses were approximately 400sf and consisted of two rooms.

Below is a step-by-step process of how we helped build bamboo houses out of woven bamboo.

1. Columns & Roof

When we arrived at the site, the two houses were in the early stages of construction. One house had concrete columns and a corrugated metal roof. The other house had columns only. Local community members were currently installing wood rafters to support the future metal roof.

Notice the bamboo “scaffolding” in the 2nd photo. Bamboo was used for everything.
 

2. Cutting the Bamboo Down To Size

During the first week, men and women from the community taught us how to build their bamboo houses. It was a very humbling experience to learn from them and work side by side with them on their houses.

It was also very interesting trying to communicate with them about what we were doing because of the language barrier. Needless to say, there were a lot of hand gestures, laughs, and thumbs up or down!

To start off on the house building process, we needed bamboo. It was either cut down nearby or transported by truck. Because our sites weren’t near any large roads, bamboo was unloaded from trucks and tied to bicycles and wagons as they made their final approach to the site.

Bamboo was stockpiled nearby. Then, we started to measure and cut the bamboo stems, or culms, based on the length, width, and height of the houses. We created separate piles of bamboo for the long walls, the short walls, and the vertical battens. More on these later.

3. Splitting the Bamboo

The next step was splitting the bamboo down the length of each stem into individual strips.

To do this, a large notch was cut in the end of the bamboo stem. Once you have it split a little, you can lay it on the ground and use your hands and feet to help split it the rest of the way. Then you do it again about 4-5 times using the same stem until you have flat strips (not concave pieces – keep splitting until you have flat pieces).

Getting the splitting started was the hardest part. Once its started, the rest of the splitting was fairly easy.

4. Cleaning the Bamboo

After splitting the bamboo, we then had to “clean” the individual strips. This meant we had to shave down the strips lengthwise to remove the residual vascular bundles scattered up and down the bamboo. (You know, those little pockets or knots you see in the bamboo…)

The bamboo strips need to be smooth and flat so that they can more easily be woven together without getting caught on each other. Removing the wooden bundles helps. It also causes a lot of blisters!

We spent the majority of the first week cutting, splitting, and cleaning bamboo.

Tools were primitive and consisted of handsaws, chisels, knives, and a crowbar.

At the end of these few days, we had piles of cleaned bamboo strips of varing sizes ready for weaving.

5. Weaving Bamboo Into Walls

Towards the end of the first week, we started weaving bamboo walls.

This was really exciting because it was something I’d never seen or done before. I was fascinated!

The setup consisted of this:
We took some of the bamboo strips from our pile of battens (remember we had 3 different piles of bamboo) and laid them on the ground at roughly 12″-18″ on center. These would form the inner structure of the walls and are what enables the over-under weaving pattern.

Then we started the first course of weaving.

Starting at one side, we slid 2 bamboo strips up and over one batten and down and under the next until the ends of the strips reached the last batten. Then, we started the next set of strips, but instead of going over the first batten, we slid these strips under the batten and over the next – alternating patterns of the previous strips. This alternating up and over and down and under sequence is what created the woven pattern.

In addition to alternating the weaving pattern, we also flipped the strips over on their backs every few courses. You can see this in the photos by the change in color from white to green.

This rotation helps with structural stability along the entire height of the wall. Clever.

Weaving continued up the wall. Because the battens are so tightly interlocked within the woven strips, the actual weaving occurs higher up on the wall and is then slid down into place.

We would weave a few courses then slide them down into place. Weave a few courses then slide into place. We continued this process all the way up the wall. To keep each course tight against the last, we would occasionally hit the top course with a handmade tool the locals built out of a bamboo stem.

We called it a “bammer” (bamboo hammer). It’s essentially a small bamboo stem with a handle cut out of it. (You can see it in the above right photo laying on the finished wall.)

After each wall was finished, it was moved off to the side to make room to stage the next wall.

In our group of volunteers, some of us would cut and clean bamboo while others started weaving. Then we’d switch to give everyone a chance.

It was hard to gauge how many strips of bamboo were needed until the actual weaving process started. Then we’d realize we were short and have to keep cutting and cleaning.

This process continued into the beginning of the following week until all walls were woven.

6. Installing Bamboo Walls

Installing the walls was actually a very easy process.

A few of us would carry each wall over to the house, stand it upright in place, and someone would go around and tie the wall to the columns at various heights with wire.

Each house also had one or two sets of windows in the front. These were framed with simple pieces of wood and infilled with woven bamboo.

In a matter of a few hours, we had all the walls installed. It was such a fulfilling experience to finally see the house taking form.

You will notice in these two photos that the bamboo is running in different directions on each house. This was a personal preference of each family.

7. Plastering the Walls & Floor

After walls were up, we were taught how to mix plaster for the walls and floor.

The plaster mixture consisted of mud, hay, water, and cow dung. Yep, cow dung.

(Cows are a sacred and protected animal in various Hindu scriptures. We were told that because the cow is holy, everything that comes from it is perceived to be holy. So by adding some cow dung to the plaster mixture, the house was receiving a blessing.)

Many of the local children started gathering mud from the nearby pond and bringing it to the site. While that was going on, we started mixing the rest of the materials together to get a thick plaster/mud consistency. Whether by hands or feet, mixing the plaster was actually quite fun (after we got over the fact that we were playing in poo)!

As mixing continued, we started applying plaster to the walls by hand. Because the mixture was so thick, you literally could throw a handful of plaster at the wall and it would stick. So our process involved throwing handfuls of mud at the wall, then coming back in, adding more plaster and smoothing it all out to a nice even consistency.

As we covered all the walls, you could definitely start to feel the temperature in the house change to a cooler, more tolerable degree. The thermal mass of just the plaster layer was significantly improving the comfort level of the house.

Not only does the plaster help with thermal comfort, it also helps protect against wind, rain, and bug infestation.

On the exterior, we plastered the walls halfway up. The reason for plastering the bottom half was to help protect the bamboo from rot and deterioration caused by water or hungry critters at the base of the walls – helping the bamboo walls last longer.  

In addition to the walls, we also plastered the floors.

A piece of plastic (moisture barrier?) was laid on the ground, then covered with a thick layer of hay (padding) before we plastered the floor and compressed it down with either our hands or paddle.

After a few days of plastering, we finally finished both houses! Seeing the finished houses was such a rewarding way to end our trip.

8. Celebrate

There was a small house dedication the morning before we left. The local Nepalese community dressed in their nice tribal attire and showed so much appreciation toward us and our work. It was a really nice and genuine experience.

Reflection

What an awesome time! I had such amazing experiences on this trip that I really can’t imagine traveling or vacationing any other way.

This was my first taste of experiencing life in a developing country and serving a group of people in desperate need of decent housing. It opened my eyes to the true struggles people face and just how much we take for granted sometimes. It also gave me a new perspective on living in the moment and practicing gratitude – things I strive to do on a daily basis.

While the trip was short, I learned so much about the world and myself. These experiences have such a lasting effect on me and impact the way I practice architecture to this day.

If you have any interest in participating in a Habitat for Humanity Global Village Build and want to learn more, please check out their website. And if I can be of any assistance, please don’t hesitate to get in touch.

To read more about another Habitat For Humanity Global Village Trip I participated in, check out my experience in Sri Lanka building clay brick houses… or check out one of our local projects here.