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Jason: In this video we will discuss a traditional Louisiana construction method called Bousillage. Bousillage is a Louisiana French term for walls made of mud. The origins of the word comes from Bous which means mud. Louisiana’s bousillage techniques appears to be a blend of French and Native American traditions. Both cultures employed similar mud walled building techniques and traditions tell us that the early French colonists and Native Americans worked together.   Commonly in the 18th and 19th centuries bousillage was used for buildings that ranged from small cottages and outbuildings to the finest of mansions.

A traditional wooden bousillage building on the water.

A traditional wooden bousillage building on the water.

Jason: The material that makes bousillage unique is the Spanish Moss.  Spanish Moss is a unique feature to the southern landscape. This flowering plant can be found hanging in the branches of any variety of trees in the more humid regions of the tropic and subtropical latitudes. In North America Spanish Moss ranges from Texas to Florida and as far north as Virginia along the eastern seaboard.   This plant is not parasitic but actually a true epiphyte and gets its sustenance from the atmosphere and it not rooted into the tree in any way.

Spanish Moss in Tree

Spanish Moss in Tree

Jason: Traditionally the moss is gathered in the spring time when it is most abundant. Most moss is gathered directly from the trees by use of a long bamboo or cane reed pole, any moss found on the ground is also gathered. Once any captured sticks or leaves are removed from the moss it is bagged for processing. Keep in mind that it takes a lot of moss for the making of bousillage.

Jason: Traditionally Spanish Moss was prevalent in southern and central Louisiana. It is this reason that the moss was such a good building material. As late at the 1940’s gathering and processing Spanish moss was a major industry in the state of Louisiana. During the 20th century Spanish moss was used for automobile and furniture upholstery.  Unfortunately, due to the heavy use of chemical exfoliates to harvest cotton; Spanish moss is a rare find in central Louisiana today.

Spanish Moss being gathered

Spanish Moss being gathered

Jason: Once the moss has been gathered it must be processed or retted. The processing of the moss is done by digging a shallow ditch usually on the site where the building will take place. The Spanish Moss is then stretched out into the ditch and buried over. This remains buried for four to five months, the time out of the sunlight kills the moss and reduces it to thin but very strong black fiber. This black fiber is mixed directly into the mud for bousillage. In some traditions the moss is boiled after being brought out of the ground this helps to remove any remaining greenish grey covering of the living plant.

Burying Spanish Moss in a ditch for processing

Burying Spanish Moss in a ditch for processing

Oswald: This is the green moss that we picked this morning. This is the way it looks like before it was retted. And this is how it looks like after it has been buried for four to five months. It has cured now and this is the type we use when we are making bousillage.

Jason: Now that the moss is prepared the soil must be chosen and gathered. For bousillage a silt soil is used. Traditionally, the soil is gathered on the high ground near the levees, often at the building site, this helps to avoid the heavy clay deposits that can be found on the river backs. After the soil is gathered it is commonly sifted to remove any large organic matter or foreign objects such as sticks and roots or rocks.

Choosing and gathering a silt soil

Choosing and gathering a silt soil

Jason: Now lets look at methods for repairing historic bousillage.

Jason: Here we are inside the Cook’s Cabin at the Oakland Plantation looking at the original historic bousillage walls. Unfortunately due to age some areas of this bousillage have failed. It has become very pliable and very frail. And its had to be removed in areas such as this. As we can see here some of the original bousillage was made with straw. Probably from here on Oakland Plantation. The repair mix that we are putting back will use the traditional Spanish moss. Once all these areas, the large and the small, are patched we will actually lime wash the wall like it was originally intended. We can see some evidence of the original lime wash still intact. This is also one of the important reasons why we have added the fiberglass reinforcement fiber. That way we can delineate between our repair work and the original bousillage.

Moss: Hello I am Moss Rudley with the National Park Service Historic Preservation Training Center. We are mixing bousillage here today at the Cook’s Cabin at Oakland Plantation. Bousillage is a mixture of loamy soil gathered along the river banks here, a small amount of lime, cured Spanish moss and in this case we are using concrete reinforcement fibers to clearly delineate between the historic material and the replacement material that we will be putting into the wall today. It will then be mixed with water and formed into loaves, placed over the rabots or in the small cracks that have formed in the historic material.

Jason: Here in this corner of the Cook’s Cabin we can see much of the original bousillage has failed. However this is fortunate for us that we can see how the original wall was constructed and most importantly what we can look at are these slats. These are referred to as batons or rabots. These are local hand-hewn cypress that are then notched into the wall. This is what will build up the wall using our bousillage. We will actually form what is called a mud cat and the mud gets laid over it and thats how we build the bousillage wall. Before we begin with any repair work we must first wet down the wall with a mist of water. This will soften the historic material and help the new material bind to it.

Water misting the wall before repairs.

Jason: Once the bousillage has been mixed with water and the wall has been moistened the repair material is pushed into the cracks and voids of the historic wall. This process is very similar to the repointing of brick or stone masonry and uses the same trowels.

Jason: In this section of the wall most of the original bousillage has failed, to replace this we must first make loafs or mud cats of bousillage to lay over the Cyprus rabots. As the wall is built up the loafs are smoothed down to bind with the material below.  Some pointing may need to be done to connect the newly laid section with the historic wall.

Jason: Once the repair work is completed the wall will need to dry out before the finish coats of lime wash are applied. The time it takes to dry will depend on the weather and airflow to the wall. Typically the wall will take a few days to dry. The original wall was constructed using the same method of laying the mud loafs over the rabots.

Jason: Now that the bousillage has cured we can apply our finish coat of lime wash.  First we wet down the wall with a mist of water. This will soften the bousillage and help the lime wash bind to it. Natural lime wash is the traditional method for finishing the interior and exterior of bousillage walls. The lime wash seals the wall but still allows moisture transfer.For more information about lime wash, both its preparation and application, please see the NCPTT website keyword limewash. (See the Application and Preparation of Limewash Video (2008-07)).

Applying limewash to the repaired walls.

Applying limewash to the repaired walls.

Jason: Bousillage buildings in Louisiana are being lost every day due to neglect, demolition, and ignorance for the material. It is important that we repair, rebuild and protect this vanishing cultural heritage.

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5 Responses to Bousillage

  1. Monique Benoit says:

    Thanks, Jason! Great video: I learned something new.

  2. jony says:

    Thanks, Jason! Great video: I learned something new.

  3. Robert says:

    Lovely video on a very interesting loam building technique. I have a couple of technical questions.

    1. At about 6:25 in the video we can see the inside of the boards that make up the outside of the wall. Am I correct in thinking that they are painted on the inside? Or is that lime wash to help protect the wood? If they are painted, why?

    2. What would be the most likely reason that the mud wall failed in the first place? Moisture from inside the building? Moisture penetrating the wall from the outside? Seismic activity? Excessive dryness?

    Thank for your important and fantastic work.

    • Jason Church says:

      Thank you for your comments, we are always happy that you enjoyed the video.
      1. The boards are limewashed on the both sides to protect the wood from the elements and moisture movement. However, this exterior cladding is a more modern addition to the building. Originally, the building would have had bousillage as the exposed material. This helps the bousillage absorb and wick moisture this action is what makes a bousillage building cooler than most other building materials. However, as the buildings were “updated” the extiors were usually covered over. In most buildings this was later followed by interior covering as well.
      2. The mud does dryout and age over time and begin to break down. Historically, the mud would be replaced every few years.

      • tom wells says:

        Bousillage is not an especially good insulater. It is dirt and responds to temperature changes.

        Bousillage reaches an environmental status quo. In Louisiana it will never dry completely, nor, if protected from rain, become wet.

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