How to build a water-tight cavity brick wall (Extended training)

The Clay Brick Association of Southern Africa describes how to build a clay brick cavity wall to improve insulation and energy efficiency.
What is a cavity wall?
A cavity wall is composed of two masonry walls separated by an air space or cavity. A well-designed cavity wall built from a high-density masonry material like clay brick offers two key benefits:
1) It provides excellent insulation from temperature extremes and noise.
2) The cavity prevents water from condensation from penetrating into the inner leaf.
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