TE HAPUA EARTHBRICK HOUSING CHARITABLE TRUST
Objectives
- To enable the production of high quality earth bricks for local use
- To promote and assist the construction of low maintenance, long lasting housing for the Ngati Kuri iwi.
- To create training and employment opportunities for local youth.
 The earthbrick trust can provide support through all stages; i.e. assistance with plans, costings, building consent; the provision of brickmaking facilities, training, construction guidance, and contacts for shared material supply.
Stabilised earth construction
The decision to use a soil-cement mix and a pressed brick was based on the more humid and extreme weather conditions of the location. The narrow peninsular of Muriwhenua means that most building sites will be exposed to strong winds and horizontal rain at times.
Soil Used: A good soil mix for a pressed brick consists of equal parts sand, silt and clay.
A soil with more sand content will make a stronger brick but will be difficult to handle immediately after pressing, being more liable to crack or chip at the corners
A soil with more clay will need more cement and more water added to activate the cement. This will lead to a stickier mix requiring more scrapping of equipment used but it is critical that the water is added at the initial mixing stage.
Many earth builders import sand, soil or gravel to add to their local supply of soil to improve the strength of the bricks, though this is more common in rammed earth or in situ construction.
Adding water
Please don’t fall into the trap that many experienced concrete workers do of thinking that water can be added later by spraying the freshly pressed brick. This may work with builder’s mix of stone chip and sand but not with soil. The clay content in the soil makes the difference because it swells and shrinks with wetting and drying.
When water is sprayed onto the freshly pressed brick the clay in the surface layer of the brick will swell, the air gaps close and water doesn’t penetrate into the brick by more than one centimetre approximately. More water sprayed on will just run off.
A simple strength test way to see if the cement has been activated is to first cure the brick for 3 weeks, then drop it from waist height. A strong brick will break into several large chunks. A weak brick will break into a number of smaller chunks surrounded by loose mix.
Shrink before laying to avoid cracking
It is also a good idea to let bricks dry out before laying in the wall. This allows shrinkage to occur and will significantly reduce minor cracking in the walls and make a cosmetic plaster finish unnecessary. In fact this is one of the main advantages with bricks – they can be pre-shrunk. This allows a wide variety of soil to be used than with in situ construction
Earthbuilding in remote rural areas
Earthbuilding projects are occurring in most remote rural areas of Aotearoa. Many of these projects are without financial support as the earth houses aren’t eligible for loans because they are being built on land with multiple ownership and are non transportable. This lack of support is unfortunate as earth homes may be the only option for low cost, low maintenance, high quality, and long term housing in these remote areas.
Because of the low economic base of these areas housing of this nature is critical to raising the standard of living
Other housing options, like most social development solutions have designed for areas of medium to high population density, with strong economic bases and developed infrastructures. They don’t match the realities of most rural areas and therefore are unsustainable.
The advantages are earths building for rural areas are:
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