Efflorescent on exterior walls
Efflorescence is caused when soluble salts and other water dispersible materials come to the surface of concrete and mortars. It's induced by low temperatures, moist conditions, condensation, rain, dew, and water added to the surface of fresh concrete to assist trowelling. It can occur very soon after exposure to moist or cool conditions or gradually, especially when it comes from within the concrete or from the subgrade.
Efflorescence may occur within the first year of a new construction project and may only be an aesthetic concern on an unpainted substrate. Efflorescence due to residual moisture within the substrate will cease naturally as the masonry dries and cures. However, when the efflorescence continues unabated then it is likely that moisture ingress from an external source is occurring, which can present significant ongoing problems.
Efflorescence does not equate to defective pavers or brick walls. In fact, it’s a normal and natural occurrence that can happen in any cement-based product.
In many cases, efflorescence will disappear on its own over time (usually after the first year of a paver or retaining wall installation).
1.Home owners should not put garden beds against rendered walls; this can cause water damage and efflorescence.
2.Your render can be cleaned with a soft brush and a hose. It is not recommended to use any chemicals as this may cause discoloration or excessive wear to your render.
3.Paint durability is not a defect where the owner’s actions have contributed to deterioration of paint work, for example the use of sprinklers, vegetation rubbing against paint work etc.