Substrate Waterproofing & NZBC E3/AS1 Compliance

In MBIE Determination 2026/015, an upper-level tiled bathroom floor was installed over plywood using an adhesive described as “waterproof”, but without the continuous impervious substrate or membrane required by E3/AS1. The adhesive was also unsuitable for the expected timber movement, and the system didn't meet B2 durability requirements.

The internal moisture compliance framework

NZBC E3/AS1 provides a means of compliance with Building Code Clause E3 Internal Moisture. Its requirements include provisions for adequate disposal of overflow water, and surfaces to be impervious.

Where waterproofing is required

Under-flooring waterproofing is required to protect the substrate in a 1.5m radius from the water source and must be installed under any cabinetry that encloses the water source's pipes and drains. Plus, at the 1.5m radius, a water stop is required to stop the tracking of any water in the installation which can occur in an adhesive bed.

Floor finishes and substrate movement

It's easy to assume that you can rely on an impervious porcelain tile and epoxy grout, or an impervious LVT or pre-sealed engineered timber floor, however potential movement in a substrate and the floor covering can cause moisture ingress. This may cause damage over time that wouldn't be noticed until the floor coverings and substrate are damaged and need replacing.

Junctions, joints, and penetrations

Waterproofing installation detailing must be robust. Areas with changes in plane, expansion joints, pipe penetration and drain details are the most common points of failure in an installation, as they have the most stress on the system. Therefore, a system needs to provide an independently tested and approved membrane, and accessories like waterproof butyl or rubber-based tapes and gaskets are essential for failure prevention.

Mapei Systems for Substrate Protection

Mapei products for internal waterproofing under floor coverings include Mapelastic Smart: a two-component cement-based tanking membrane. One-component membranes include Mapelastic AquaDefense and Mapegum WPS, which are commonly used for interior waterproofing, and once cured don't re-emulsify when subjected to standing water. All three Mapei membranes are VOC emissions-tested and when used with Mapeband Easy or Mapeband SA waterproof tapes and gaskets, provide robust solutions for the protection of internal substrates.

When designing areas like shower floors, it's important to consider there is the correct positive runoff for water to drainage points. In this case, Mapei can provide suitable products to achieve this over any substrate. Forming falls must also be done prior to the installation of the waterproofing membrane.

E3, B2 and the Mapei System Warranty

When specified and installed as complete systems within the relevant appraisal scope and Mapei requirements, these solutions support compliance with NZBC E3 Internal Moisture and B2 Durability. Eligible installations may also be supported by a 15-year Mapei system warranty, subject to relevant terms and conditions.

Mapeband Easy

Mapei Products in New Zealand

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Mapeband Easy is made from a central core of vapour-proof and waterproof elastic rubber sandwiched between two layers of alkali-resistant, non-woven polypropylene fabric.

Waterproofing corners between adjacent walls and between walls and floors.
Waterproof elastic control joints on terraces, balconies, etc.

Certifications:

VOC Emissions tested
VOC Content tested

Mapeband SA

Mapei Products in New Zealand

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Self-adhesive butyl tape with alkali-resistant, non-woven fabric for elastic waterproofing systems. Mapeband SA is a self-adhesive tape made from butyl rubber with alkali-resistant, non-woven polypropylene fabric bonded on the outer surface that guarantees excellent adhesion for the waterproofing system to be applied over it.

Waterproofing corners and fillets between floors and walls on terraces, balconies and in bathrooms.
Sealing different types of material (bitumen membranes, metal, ceramic and cementitious screeds).
Adheres to various types of non-absorbent substrates such as aluminium, copper, steel, plastic, bitumen waterproofing membranes, ceramic and to absorbent substrates such as concrete, masonry, aerated concrete, fibre reinforced cement and render.
Sealing small, hard-to-reach fillets such as those between window and door fittings, ledges and substrates.

Certifications:

VOC Emissions tested

Mapegum WPS

Mapei Products in New Zealand

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Quick-drying flexible liquid membrane for waterproofing internal surfaces.

Waterproofing walls and floors in bathrooms and shower cubicles before laying ceramic tiles, natural stone and mosaic.
Waterproofing kitchen walls and floors, and work tops before laying ceramic tiles and natural stone.

In the opinion of BRANZ, Mapegum WPS, Mapelastic, Mapelastic Smart and Mapelastic AquaDefense Wet Area Membranes, if designed, used, installed and maintained in accordance with the statements and conditions of this Appraisal, will meet the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1 (b) 15 years and B2.3.2. Mapegum WPS, Mapelastic, Mapelastic Smart and Mapelastic AquaDefense Wet Area Membranes meet these requirements.
Clause E3 INTERNAL MOISTURE: Performance E3.3.6. Interior wet area floors and walls incorporating Mapegum WPS, Mapelastic, Mapelastic Smart and Mapelastic AquaDefense Wet Area Membranes will meet this requirement.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. Mapegum WPS, Mapelastic, Mapelastic Smart and Mapelastic AquaDefense Wet Area Membranes meet this requirement

See BRANZ Appraisal 848 for full information.

BRANZ Appraised

Environmental Product Declaration (EPD)

Mapelastic AquaDefense

Mapei Products in New Zealand

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Ready to use rapid-drying liquid membrane for waterproofing damp areas such as bathrooms, showers, laundries, saunas, balconies and terraces before installing dressing material.

Waterproofing before applying ceramic, stone, and mosaic coverings in:

Bathrooms and shower cubicles;
Laundry rooms;
Saunas and damp environments in general;
Balconies and terraces.

Mapelastic Aquadefense can be applied on:

Concrete;
Cementitious screeds and screeds made using special binders (Topcem, Mapecem, or Mapecem Pronto);
Plasterboard (for application in interior only);
Old ceramic tiles, terrazzo, and stone material;
Cementitious render

Clause B2 DURABILITY: Performance B2.3.1 (b) 15 years and B2.3.2. Mapegum WPS, Mapelastic, Mapelastic Smart and Mapelastic AquaDefense Wet Area Membranes meet these requirements.
Clause E3 INTERNAL MOISTURE: Performance E3.3.6. Interior wet area floors and walls incorporating Mapegum WPS, Mapelastic, Mapelastic Smart and Mapelastic AquaDefense Wet Area Membranes will meet this requirement.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. Mapegum WPS, Mapelastic, Mapelastic Smart and Mapelastic AquaDefense Wet Area Membranes meet this requirement

See BRANZ Appraisal 848 for full information.

BRANZ Appraised

Environmental Product Declaration (EPD)

Mapelastic Smart Waterproofing Membrane

Mapei Products in New Zealand

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Two-component, high-flexibility cementitious mortar, applied by brush or by roller, for waterproofing concrete surfaces such as balconies, terraces, basins and swimming pools, and for protection against the penetration of aggressive agents.

Waterproofing hydraulic channels, dam faces, and basins.
Waterproofing bathrooms, showers, balconies, terraces, swimming pools, etc. before laying ceramic tiles.
Waterproofing of plasterboard, render or cementitious surfaces, lightweight cement blocks and marine
plywood.
Flexible protection layer of new concrete structures or repaired structures subject to minor deformation under
load.
Protection of cementitious renders or concrete with cracks due to shrinkage, minor movement caused by temperature variations or dynamic stresses due to the passage of vehicles, against water ingress and aggressive elements from the atmosphere.
Protection of concrete pillars and beams and road and railway viaducts repaired with products from the Mapegrout or Planitop ranges against the penetration of carbon dioxide.
Protection of structures with an inadequate concrete cover of the reinforcement rods against the penetration of aggressive elements.
Protecting concrete surfaces that come into contact with seawater, de-icing salts such as sodium chloride and calcium and sulphate salts.

In the opinion of BRANZ, Mapelastic and Mapelastic Smart External Waterproofing Membranes, if designed, used, installed and maintained in accordance with the statements and conditions of Appraisal 485, will meet the following provisions of the NZBC:

Clause B2 DURABILITY: Performance B2.3.1 (b) 15 years and B2.3.2. Mapelastic and Mapelastic Smart External Waterproofing Membranes meet these requirements.
Clause E2 EXTERNAL MOISTURE: Performance E2.3.1 and E2.3.2. Decks and balconies incorporating Mapelastic and Mapelastic Smart External Waterproofing Membranes meet these requirements.
Clause F2 HAZARDOUS BUILDING MATERIALS: Performance F2.3.1. Mapelastic and Mapelastic Smart External Waterproofing Membranes meet this requirement.

See BRANZ Appraisal 485 for full information.

BRANZ Appraised

Environmental Product Declaration (EPD)

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