Rammed
Earth Homes Rammed earth
construction is an old
building method that has seen a revival in recent years as people seek
to use low-impact materials as well as employ natural building methods.
Traditionally, rammed earth buildings were common in arid regions where
wood was in scarce supply.
Rammed earth homes have walls constructed from a mixture of sand,
gravel and clay. Sometimes an added
stabilizer is required. In earlier times it was lime but today the
stabilizer of choice is cement.
Formwork is used to create the desired shape of the wall. Damp material
is then poured to a depth of between 4 to 10
inches. A pneumatically powered backfill tamper - something like a
pogo stick with a flat plate on the bottom - is then used to compact
the material to around 50% of its original height. Further layers of
material are then added and the process is repeated until the wall has
reached the desired height. Once the mixture is set the forms are
removed and the wall is water sealed.
In modern variations of the method, the walls are
constructed on top of conventional footings combined with a reinforced
concrete
base. A horizontal layer of
styrofoam can be used to provide
extra ground insulation.
Advantages:
Thermal mass: Rammed
earth construction has
excellent thermal mass: this means that it heats up slowly during the
day and then releases the heat during the evening. This characteristic
serves to even out daily temperature
variations and reduce the need for air conditioning and heating.
Sound proofing: The
thickness and density of the walls provide excellent sound proofing
Fire proof: The
materials used in the
walls make them virtually fireproof.
Disadvantages:
Weak insulator: rammed
earth is not a good insulator. Like brick and
concrete (which also have excellent thermal mass), rammed earth must be
insulated in colder climates.
Before the use of cement as a stabilizer, rammed earth buildings were
best suited for dry climates with limited availability of alternative
building
materials such as wood. With the introduction of cement
stabilizers and weatherproof insulation for the walls, rammed earth has
become a viable building material for wetter climates.
Additional
resources on rammed earth construction coming.
