Inground and Basement Waterproofing Design
Independent review of in-ground and basement waterproofing designs — ensuring every specification meets site conditions, NCC requirements, and long-term performance.
When it comes to the requirements for basement waterproofing, there are a number of considerations that can influence the waterproofing system that is applied. Each site and project can be different and should take a bespoke approach to basement design based on the site conditions and intended use.
Why do I need to Waterproof my Basement?
The answer to this question can be wide and varied, such as the project locations that look to have basements as part of their structure. The National Construction Code (NCC) prescribes that certain levels of amenity need to be maintained for habitable spaces but Councils and Water Authorities can also prescribe the need for basements to capture and either retain or dispose of water effectively.
The reasons for ‘tanking’ a basement can include groundwater, flood zones, capacity of stormwater in the area, contaminants in the soil, the type of soil and adjacent land or properties.
What is required under the NCC 2025 for Basement Waterproofing?
NCC 2025 consolidates water-related Performance Requirements into F1P1 and introduces a defined term for “water” that includes sub-surface water, surface water seepage and rising damp.
For below-ground structures, that is a major compliance shift.
Basement walls, below-ground slabs, lift pits, plant rooms, car parks and service spaces all need a clearer waterproofing strategy, especially where the system will be concealed after construction.
The key issue for project teams: there is no generic Deemed-to-Satisfy pathway for new-build below-ground waterproofing.
A Performance Solution needs to show how the proposed approach manages the relevant water types and protects the building from unsafe conditions, deterioration, loss of amenity and damage.
Waterproofing Integrity has released a white paper explaining the change and what it means in practice.
Upcoming CPD Session: NCC 2025 and below-ground waterproofing: what changes?
Monday, 29 June 2026, 1:30 – 3:00 PM (Sydney Time)
Where can I find out more?
Tell us about your project. We’ll have the right specialist in touch shortly.