ECO CONSTRUCTION

Some of the advantages of straw bale construction include:
Straw bales are made from a low-cost product.
Insulation values of R-30 – R-35 can be achieved.
The thickness of straw bale walls can help reflect sunlight into a room at openings, and provide space for window seats.
They are relatively easy and cost-efficient to install.
Straw bales have a low-embodied energy.
With good maintenancestraw bale construction is very durable.
Straw bales are 100% biodegradable.
Properly-constructed straw bale walls can offer better fire resistance than timber frame construction.
Some of the disadvantages of straw bale construction include:
Moisture and mould are significant risks. Bales must be kept dry to avoid compressed straw expanding due to moisture absorption, which can lead to cracking.
Fire is also a risk, however, because of the density of bales, fire tends to smoulder rather than spread when an ignition source is removed.
As it is not a conventional building material, familiarity among builders, and building regulations approval can present obstacles to use.
Wall thicknesses mean that more of the building’s overall floor space is unusable.
Unless straw bales can be sourced from near the construction site, the cost of transporting them can be high.
Care must be taken to keep rodents and other small animals from infiltrating straw bales during construction.
Straw dust can cause breathing difficulties for people with allergies.
Rammed earth is an ancient form of construction, generally seen in drier hotter parts of the world. Although many rammed earth structures exist in this basic form, a new ‘stabilised’ rammed earth variant has been developed which adds a small amount of cement (5-10%) to the mixture to ensure strength and durability. 
 
Traditionally, a wooden pole is used to ram the earth into the formwork, but modern methods now use a mechanical ram. 
 
The process is labour intensive, but is considered to have a low environmental impact depending on materials used (cement content) and source of those materials. While some elements of the rammed earth wall will have a low embodied energy, cementitious products do not.

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