Sustainable Services
Rammed Earth Construction
One of the Oldest Construction Techniques — yet can fulfill Modern Human Housing Requirements.
Rammed earth is a natural construction technique that involves compacting a damp mixture of soil with correct proportions of clay, sand, gravel, and silt. Sometimes a small amount of cement is added to increase strength and durability.
The soil mixture is placed in formwork and compacted to about half its original height. Rammed earth behaves as heavyweight masonry with high thermal mass — absorbing heat and releasing it when ambient temperature drops.
Most rammed earth builders today use pneumatically powered tampers to quicken what was once an extremely labor-intensive process.
Materials Required
Earth (Soil) — Use rough, coarse sand with varied particle sizes. Clay acts as the binder holding the aggregate together. Pure clay cannot be used alone as it expands when wet and contracts when dry — it needs aggregate for stability.
Wooden Framework — Formwork holds the mixture in position while it is compacted. Modular rammed earth panels allow walls up to 2.2 meters long at variable thickness from 150mm to 350mm, and up to 2.4 meters in height.
Cement — Ordinary Portland cement is sometimes added to stabilize and strengthen the mixture, especially in sandy soils. It also provides good resistance against rain effects on the rammed earth walls.
How to Build a Rammed Earth House — Step by Step
Step 1 — Site Preparation — Remove 1–2 inches of topsoil and store for post-construction landscaping. Clear all organic matter, compress the site, then mark wall layout using limestone powder.
Step 2 — Foundation — Use rubble trench foundations (2ft×2ft trench with 3 layers of compacted gravel + 1.5ft stem wall) or concrete foundations (footers + stem wall at least 1.5ft above ground as moisture break). Dig the foundation trench at a 2% slope for drainage.
Step 3 — Rammed Earth Walls — Prepare a cohesive sand/clay mixture with 5% Portland cement (by weight) for stabilization and 10% water for compaction. Pour into formwork in layers and compact each layer to 60–70% of its original height. Cure each layer for 24 hours before the next. Wall thickness should be at least 1/10th of wall height — typically 12–24 inches.
Step 4 — Windows, Doors & Ventilators — Pre-determine door and window locations before building walls and leave hollow spaces for them. Steel or aluminum frames can be fitted later. Place ventilators at the top of walls — no frame needed as the roof acts as lintel.
Step 5 — Roofing — Use a wooden frame roof, bamboo roof, or lightweight steel panels. Bamboo is cheap, natural, and renewable — giving almost the same performance as a steel roof.
Step 6 — Plastering — Rammed earth walls have natural aesthetic finish and generally do not need plastering. If built without cement, apply earthen plaster and a sealing layer to resist weathering. In heavy rainfall areas, apply a waterproofing course.
Step 7 — Flooring — Compact the ground, apply fine clay and water plaster, then coat with linseed oil for a smooth finished surface.