A basement area requires a suitable waterproofing system (traditionally called tanking). We now call it Structural Waterproofing as tanking is created with specifics materials and construction methods. The first thing we need to know is the areas end usage, is it existing or new build, as there are different waterproofing criteria for a dwelling, store, or a car park etc.
In existing basements, waterproofing is usually carried out from the inner wall surface. Often using a Cavity Drain Membrane as the older wall/floor masonry may be in a weakened condition and it will not put additional load on the floor and wall structure, sometimes a combination of coating and membranes are used. Within its design limits, a cavity drain membrane will manage the failure of the walls and floors of the building ability to resist water.
I have found in the Edinburgh new town area the cellars floors are often well-drained and have no water table issues. This is due to their construction and the site geology. The Cavity Drain membrane system, is often used to control the rainwater percolating down through the pavement and porous ground above the under-pavement cellar.
New basement construction sites have a different set of waterproofing problems compared with existing building’s, which have a history of resisting water. In a new building, you are excavating underground (into the unknown), and the new site has a lack of water history. Therefore, more investigation is needed—starting with a desk study followed by a site inspection. The research helps in select materials and create a suitable specification, which needs to address any ground contamination due to past usage of the land, ground gases, i.e. Radon and potential flooding of the area due to its location.