External waterproofing of foundations is essential for every building with an undercroft basement, or habitable living area. Foundations and retaining walls are constantly exposed to moisture ingress. Foundation waterproofing or external basement wall waterproofing is required, in order to avoid serious damage to the structure of the dwelling, and major cosmetic damage to rooms inside, including, but not limited to, swollen timber skirting, blistering paint, white set, & carpet/timber flooring.
A retaining wall can be useful for both practical and aesthetic purposes; either to terrace a sloping site to create serviceable space, or simply to create profile and interest in an otherwise uniform and featureless landscape. Nevertheless, whatever the reason for its creation, a retaining wall needs to be well made to ensure it remains intact, safe, and uncomplicated.
One of the most important fundamentals in worthy wall construction, is creating a solid foundation. The base of a retaining wall should be set below ground level and made from compacted soil and a layer of at least 80mm of concrete.
Active drainage is critical for a retaining wall, otherwise water pressure, known as hydrostatic pressure, will form up behind the wall and lead to swelling or fractures.
Methods to achieve decent drainage, include using at least 300mm of a granular material such as gravel in the backfill (the material directly behind the wall). Compacting the backfill progressively, will also help to deflect pressure downward, rather than against the wall.
Other ways to create good drainage include installing a perforated pipe along the inside bottom of the wall, that feeds into a storm water drain, and creating small weep holes in the wall, which will allow water to drain out through them.