Dirt Dobber Construction (DDC) offers a full turn key service for natural earth plasters.

What is Natural Plaster?

Natural plaster is a a organic mixture of indigenous soil used to make the compressed earth blocks (CEB’s). The organic mixture is composed of lime, sand (of any color and texture) and Nopal Cactus juice being used as a binder. Nepal Cactus (pictured to the right) is the most important ingredient in natural plaster due to its ability to be a flexible membrane when used in a plaster. It can achieve equilibrium in moisture exchange within the wall system and still be of high tensile strength. Indigenous to most areas of Texas and the South West region, it is easily harvested and conditioned for use in the plaster.

Can anyone make Natural Plaster?

Yes. Volunteers in Abilene, Texas (pictured below left) cut Nepal cactus harvested from a fence line 3 blocks from the project site to be used in the exterior plaster.

How do you make Cactus Juice?

Simple. After you have harvested some Nepal Cactus from a fence line utilizing a machete and cut the leaves of the plant into 1 inch square pieces, you fill a 55 gallon drum ¼ full (Pictured Below). Fill the rest of the drum with water and let sit in the sun for 2 to 4 days to allow the enzymes to secrete from the Nepal. When it is ready it will have the consistently of snot. Simply use this water in with your sand, soil ,and lime to make the plaster.  

Can the natural lime plaster be applied directly to a CEB wall?

Yes. It is applied directly to the CEB wall in two coats; a scratch coat and a finish coat. First you will need to wet the wall surface prior to the application of any coat to prepare the block (Pictured left). Once this is accomplished you can install the base coat (scratch coat) to the blocks. This is made up of the same soil used in the block manufacturing, lime, and cactus juice. After the coat has been applied and is still moist the finish coat can be installed. The finish coat consists of sand, lime and aggregate (horse hair), and cactus juice. The lime reacts with the moisture and begins to cure within seconds of being applied to the wall and must be routinely watered through the course of the application process, and after to ensure proper hardening. The amount of misting the wall surface required is dependent on the temperature and humidity at the project site. Hot dry days require the most attention. Pictured (Left bottom) shows the two stages of the application process. The naked CEB is left of the corner of the house, a scratch coat (dark brown) to the right and the (white) finish coat in front of the worker dressed in white. The Nepal cactus juice used in the plaster will phase change with the atmospheric conditions allowing the heat flux process to take place. This will make it possible for moisture to pass through the wall membrane and from the interior of the building. This water vapor exchange keeps the interior climate of the building stable and is the primary reason these buildings can easily achieve 80% or greater in cooling cost reductions.