The mud wall is a mixture of soil, water, lime, hay and cow
manure. Mud walls that are air dried have an approximate life span of 30 years
before they crumble and require repair/replacement. Cow manure is added to the
mud wall mixture for added strength and waterproofing. It is important to use a
soil mixture that has few rocks and to compact the mixture as it is built up to
remove air bubbles. Rocks and air bubbles will cause the mud wall to crack and
break. The thermal mass created by a mud brick wall absorbs solar energy during
the day and release it slowly at night. Ideally, mud bricks that have been kiln
dried would be used to increase the longevity of the built wall.
Mud (adobe) walls have a low embodied energy with most
energy involved in their formation coming from physical labour and the sun (air
dried). The components in mud walls are also returned to the earth over years
of exposure to rain. Mud walls have good fire resistance and sound insulation
but are not good thermal insulators. They lack good thermal insulation
properties because they are so densely packed so they do not trap air within
the walls, thereby not restricting the transfer of heat between the external
and internal environments.
