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Straw Bale Insulation

Straw bale insulation has been used in the US and parts of Europe extensively. Straw is a by-product in wheat/ oat/ barley/ rye/ rice farming. After the chaff and grain have been removed at harvest, the straw stem is left over. The straw stem is then bundled into a ball or block and used for livestock bedding, fuel, gardening or in our case- insulation. Straw bales are great natural insulation that is renewable and sustainable.

strawbale  house round

There are two options in straw bale construction: one is where the straw bale act as the structural wall and one, where the structure of the house is made of a frame and straw is used as the insulator only (also called infill). The biggest worry for builders is to ensure that the straw bales stay dry before, during and after installation; as a wet straw bale will likely start to compost. To protect the straw bales from the environment moisture, rain and snow usually a clay plaster is applied, though other options are possible.

Advantages of straw bale insulation:

  • Superior insulation value compared to other products, keeping your heating costs lower

  • A natural and renewable product that can be recycled or used as compost

  • The thick walls of straw bale homes add character. Walls of the same thickness of other construction methods are a lot more  expensive to construct

  • Straw bale walls help regulate the moisture level in your home

  • Straw bale walls act as a thermal mass, storing heat from the sun for when you need it

  • Due to the thickness of the walls window seats are easily achievable

  • Walls can be carved with a chainsaw or knife, which makes it possible to create funnily shaped walls and integrated shelves

  • Straw bale homes are very fire retardant due to the denseness of the material- this runs contrary to logic but is true


Disadvantages of straw bale insulation:

  • The thick walls mean losing floor space either inside the house or outside the house

  • It is vital that straw is kept dry so roof overhangs are highly recommended but might not fit the visual appeal of your home

  • It is difficult to predict the wall costs as it depends on availability and transportation costs


Straw bale houses are super-insulated, usually far surpassing the legal requirements for insulation. The cost of straw bales can vary quite a lot depending on where you are, how accessible it is in that area and the potential transport cost. Straw bale homes do come under the 'Alternative Solutions' in the building code in NZ. 

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