Waterproofing is a chain, not a coating.

One-sentence thesis

Waterproofing is the result of a connected water-management system. The coating or membrane is one layer inside that system, not a substitute for it.

Why this matters in Bali

A Bali residence may receive heavy rain, wind-driven rain, high outdoor humidity, wet construction, frequent indoor-outdoor movement and long periods of vacancy. Roofs, terraces, bathrooms, pools, planters, walls, thresholds and ground-floor assemblies are often designed and built by different teams. Water does not respect those scope boundaries.

A failure may appear as a ceiling stain, damp skirting, lifting floor finish, salt deposits, mould odour, swollen joinery or a wet wardrobe. The visible symptom may be several metres from the entry point. Recoating the visible area can hide the symptom without correcting the route.

The owner therefore needs more than a product warranty. The owner needs the interfaces to be coordinated and the evidence to be retained before closure.

The six-part control chain

1. Keep water away where possible

The first layer is not a membrane. It is the shape and level of the project.

Questions include:

• Does the finished ground fall away from the residence?
• Can roof water discharge without returning toward the building?
• Are planters, pools and retaining walls separated from sensitive walls?
• Are internal floor levels protected from terrace and landscape water?
• Can a blocked drain create a route into the residence?

A membrane is placed under unnecessary pressure when the project directs water toward it rather than away from it.

2. Move water through a defined primary route

Water should reach a drain, gutter, outlet, channel or permeable ground through a deliberate fall. A drain that is present but higher than the surrounding finish does not perform the same function as a drain at the low point.

The design should resolve:

• falls and low points;
• outlet position and capacity;
• transitions between different finishes;
• debris and leaf exposure;
• cleanability;
• destination of discharged water.

3. Provide a safe route when the primary route is compromised

Primary drains block. Rain intensity varies. Maintenance is delayed. A resilient design asks what happens next.

Examples include:

• roof overflows below the waterproofing termination;
• terrace edges or secondary outlets that discharge safely;
• thresholds that remain above a temporary water level;
• landscape routes that move excess water away from occupied rooms;
• accessible inspection points before buried drainage becomes impossible to verify.

The secondary route is not permission to undersize the primary system. It limits the consequence when normal assumptions fail.

4. Keep the water-control layer continuous

The membrane or waterproofing layer matters most at the places where continuity becomes difficult:

• wall-to-floor junctions;
• changes in plane;
• internal and external corners;
• drains;
• pipe penetrations;
• door and window thresholds;
• parapets and roof edges;
• construction joints;
• movement joints;
• fixings added after waterproofing;
• interfaces between packages.

The field of a membrane is often easier than its edges. A project should therefore spend disproportionate attention on transitions, terminations and penetrations.

5. Protect the system before and after testing

A correctly applied system can still be damaged by later trades. Screeds, tile works, balustrades, glazing, equipment supports, lighting, planters and MEP penetrations can cut or puncture work that was previously accepted.

Protection should answer:

• Who may work above the finished membrane?
• Which fixings are permitted?
• How is the membrane protected before screed or finish?
• How is damage recorded and repaired?
• Which areas require a repeat test after later work?

6. Preserve access and maintenance

Water systems are not static. Drains collect debris. sealants age. outlets corrode or loosen. movement opens joints. vegetation grows. staff routines change.

A durable system needs:

• accessible drains and strainers;
• safe roof access;
• cleanable channels;
• visible overflow points;
• inspection intervals;
• known product and repair records;
• a route for reporting and closing defects;
• Building Passport entries where relevant.

Why “three coats” is not a specification

The number of coats alone does not establish performance.

A meaningful system specification may need to define:

• substrate preparation and moisture condition;
• primer;
• total cured thickness;
• reinforcement requirements;
• crack and joint treatment;
• allowable movement;
• detail at drains and penetrations;
• curing or protection time;
• compatibility with screed, tile adhesive or protection layer;
• exposure to UV, heat and standing water;
• repair method;
• inspection and test criteria.

Some liquid-applied systems require full reinforcement. Others use reinforcement at details or movement-prone areas. Torch-applied, synthetic sheet, liquid-applied and cementitious systems each have conditions in which they may or may not be appropriate. DALLEAU should not publish one universal product rule. The appointed designer and specialist must define the system for the substrate, movement, exposure, finish and maintenance context.

Four common failure patterns

Good product, wrong substrate

Dust, laitance, contamination, trapped moisture, weak screed or active cracking can undermine adhesion and continuity.

Good membrane, no safe fall

Standing water increases exposure, concentrates dirt and turns a small detail defect into a persistent load.

Good field application, weak interfaces

A drain, threshold, parapet or penetration may create the real path of failure even when the main area appears well coated.

Good installation, damaged after acceptance

A later fixing or unrecorded penetration can defeat a previously tested layer.

What DALLEAU would ask to see

• the owner objective and consequence of failure;
• the approved system and responsible specialist;
• coordinated falls and drainage routes;
• primary and emergency outlets where required;
• details at every transition and penetration;
• access for inspection and cleaning;
• mock-ups for unusual or high-consequence conditions;
• hold-point photographs before closure;
• test method, conditions and result;
• repairs and retests;
• maintenance instructions and responsible party.

What this note does not prove

This note does not identify the source of a specific leak. It does not establish that one membrane type is always superior in Bali. It does not replace geotechnical, structural, hydraulic, envelope, roofing or manufacturer review. It does not guarantee the absence of future water ingress.

Project implication

When waterproofing is treated as a late trade package, the owner receives product names and invoices. When it is treated as a continuous owner-side system, the owner can see where water should go, who owns each interface, what must be inspected and what evidence must remain after handover.