How to Write a Waterproofing ITP for Wet Areas

Confirm the compliance pathway and scope first

Before drafting, establish the building class and room/use scope, state or territory, applicable adopted NCC edition and variations, and approved compliance pathway. The ABCB’s waterproofing overview is expressly a general guide for Class 1 houses; it does not establish all requirements for apartments or other building classes. The ABCB says adoption and variations are controlled at jurisdiction level, and code editions may be adopted on different timelines.

For example, the NCC 2022 Housing Provisions Part 10.2 includes wet-area construction and membrane provisions, but do not assume this pathway applies to every building or project. Record the actual approved pathway and governing documents. Do not combine portions of pathways based on convenience.

Map each installation stage to its source and evidence

Structure the ITP around work that can be observed: document/system confirmation; substrate and environmental readiness where required by the selected system; junctions, penetrations and drainage details; membrane application and required coats/layers; protection and pre-cover review; testing if the project documents require it; rectification and handover.

Use the specific approved drawings, specification, compliance documents and current product instructions to populate exact requirements. Product systems and substrates differ. The public NCC text and CSIRO/APAS specification provide context but do not replace the system instructions or project’s acceptance criteria.

Resolve documents and system compatibility before setting criteria

Record the exact membrane, primer, reinforcement/accessories and substrate combination where the project requires it. Verify that the specified products are compatible and that instructions correspond to the approved system and intended exposure. Do not infer application thickness, coverage, coat count, cure time, test method or recoat window from another product or generic internet material.

If the approved detail, code pathway and product instructions appear inconsistent, log the references and ask the designer, certifier or responsible project authority identified in the procedure. Do not select one requirement yourself or combine code options.

Set control points only from assigned project rules

Identify any inspection before work becomes concealed, but assign H/W status, notice period, recipient and release authority only where the contract or approved quality plan defines them. If the project has no stated stop, seek agreement through the project process before writing a hold point into the plan.

Keep installer checks, builder quality review, client observation, certifier inspection and regulatory certification distinct. A field record documents an observation; it does not itself grant a statutory certificate or delegated release authority.

Plan the evidence dossier for handover

A waterproofing evidence dossier should be traceable by building, floor, room/zone and installed system. Assemble only the records required by the project and applicable jurisdiction. Useful index fields can include the approved detail and revision; product and batch identifiers if required; substrate/readiness evidence; application records; pre-cover observations/photos; test or inspection reports where specified; nonconformance and reinspection closure; and required certificates.

Use an evidence index that points to source file names/IDs, dates, locations and the responsible record issuer. Keep actual measured values and certificates in their original project records. Do not imply that an example dossier proves compliant work.

Fictional example: room-by-room evidence trail

Fictional teaching example only. A hypothetical internal bathroom package uses an approved membrane system and contains a tiled shower and floor/wall junctions. No real project, code decision, product value, test result or certification is represented.

1. Create a room/zone identifier and link it to approved drawing and detail revisions.
2. Record the confirmed compliance pathway, membrane system and current compatible instructions in the source register.
3. Draft checks for the actual substrate, junctions, penetrations, application and pre-cover stages shown in those approved documents.
4. Assign notice, witness or release controls only from the project contract or approved quality plan.
5. Index the completed blank/field records, location-tagged evidence and any required project-issued certificates by the same room/zone identifier.