Salt attack is an increasingly important problem in Western Australia due to our high level of coastal development and a growing salinity problem in our wheat belt and agricultural areas. Damage to buildings by “urban salinity” or “salt damp”, results from salt and water moving through capillary action through the pores of materials such as concrete, bricks, mortar and stone. Evaporation of the water causes crystallisation of the salts on the surface and in the pores of the building material, causing fretting. Typical symptoms in buildings include salt crusting on bricks, concrete and pavers, and corrosion of underground services.
The Building Code of Australia (BCA) already makes provision for building within one kilometre of the coast, eg requirement for galvanised lintels to protect buildings against salt damage.
Other common building practices and materials also take potential salt damage into account. The use of colorbond roofs, PVC and copper pipes, rolled brick joints and black plastic membrane under slab also act to protect the building structure against salt attack.
Builders can take additional measures to protect structures against salt attack including:
- More extensive use of 25mpa concrete other than its limited use currently (on balconies etc); and
- Curing and mechanical vibration of concrete on slabs (normally only on suspended slabs).
Salt attack is a problem that won’t go away but consumers need to be educated that the building industry is taking adequate measures to protect their new homes against salt attack. Nevertheless there is a need for continuing vigilance and ongoing maintenance especially for residents in beachside suburbs.