A Piece of the PISE: Pneumatically Impacted Stabilized Earth Walls
The Pneumatically Impacted Stabilized Earth (PISE) wall is a centuries-old building technique. Previously referred to as rammed earth or pisé de terre (going back to its French origins), it is a mixture of mud and cement packed into a form and compacted into a strong, fast-drying wall. The old way to do it was to build a two-sided form and pack “earth” into it layer by layer, ramming each layer as you go.
Newer techniques have updated the process to fulfill the modern need for speedy construction, differentiating PISE construction from rammed earth. Nowadays only one side of the form need be built and the mud is sprayed into the form, providing all the thermal and structural advantages of a conventional PISE wall, but with much less time and labor.
PISE walls are rising in popularity because of their energy efficiency and eco-friendly characteristics. Some benefits include:
- Formwork that can be used and reused many times for separate walls, cutting down on wasted materials.
- Thermal mass creates excellent energy storage and efficiency, maintaining consistent indoor air temperatures—excellent complement to passive solar design.
- Very resistant to insects and fire.
- The wall itself is biodegradable and reusable.
- Strong and long-lasting. Properly built PISE or rammed earth walls are nearly as strong as concrete and can last hundreds, even thousands, of years.
Building a PISE wall requires pneumatic spray tools and a good amount of skill. Proponents, such as noted green architect Eric Corey Freed, claim that the speed of wall construction easily makes up for the cost of hiring a contractor and skilled workers, even making it competitive with traditional wood framing.