Both old and new basements should be tanked with two waterproofing systems. Either an internal or external tanking system should be applied to the walls and floor slab. A second system should then be installed using drainage membranes. This system will be able to deal with any changes in the future and ensure that any leaks are directed to sumps and pumped back out of the building. This will ensure that expensive remedial works are not required, after the building has been occupied. In combination with ventilation and insulation, this should ensure that all basements meet the highest standards for habitation.