Building Code changes to E3 and our solution to specifying wood flooring in wet areas

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In the New Zealand Building Code, section E3 refers to Internal Moisture. It states that all surfaces in wet areas must be impervious, easily cleaned, and have adequate ventilation. In 2021, the E3/AS1 requirements in the Building Code were updated with additional requirements for wood flooring in wet areas. 

In this article, we explain what these E3 changes are and how to gain compliance and submit an alternative solution for wood flooring in wet areas.

What are the E3 changes? 

Since 2021, using timber as floor linings and finishes in wet areas is no longer an Acceptable Solution E3/AS1 in the Building Code. This change applies to wet areas such as kitchens, bathrooms, toilets and laundries but does not impact living areas, dining spaces, hallways, or front entrances. 

As a result, timber flooring in wet areas must be submitted for Building Consent using one of two compliance pathways:

  1. Alternative Solution (D3 PVA Joints/Caulk Perimeter)
  2. E3/AS2 (Wet Area Membrane)

To prepare for these changes, the team at Forté has had discussions with MBIE, Auckland Council, BRANZ, Masterspec, the waterproofing association, and the Australasian Timber Flooring association. In the process, we have gathered information and put together an effective specification that meets the new building code requirements. 

To minimise delays or RFI's (request for information) from council, all projects submitted to council should include the Forté Timber Overlay Flooring System PTS in the consent documentation. Additionally, our timber flooring is CodeMark certified, ensuring an efficient consent process. 

To assist specifiers, we have updated our Timber Overlay Flooring System and the relevant documentation to ensure it aligns with the new requirements.  If you’d like to learn more, please book a virtual or face to face education session by contacting your Territory Manager

Please note: Replacement of floors, walls / ceilings of an existing dwelling DO NOT need consent. More information around this can be read on page 82 in the 'Building Work That Does Not Require A Building Consent' on the Building NZ website.


Floors areas covered under E3 

As per the NZBC Clause E3, the areas are defined as floor surfaces of any space containing sanitary fixtures or sanitary appliances such as kitchens, bathrooms, laundries, and toilet facilities. The Acceptable Solutions are limited to common linings and finishes, such as ceramic tiles, sealed or polished concrete floors (slab on grade), and waterproof sheet material with sealed joints.

It is important to note that the change in amendment will have no effect on wood flooring being installed in living areas, dining spaces, hallways and front entrances. 


How to specify timber flooring in wet areas

The Alternative Solution for E3 must be used for kitchens, bathrooms, toilets and laundries of single-dwelling residential homes, as well as kitchen areas of multi-dwelling buildings such as apartments. However, on the rare occasion that the kitchen sink overflows, do not comply with the requirements under 2.0.1(b) of E3/AS1, a wet area membrane must be specified beneath the wood flooring. 

1. Alternative Solution for E3

Glue-down installation with sealant applied as per the Forté Timber Overlay Flooring System Installation Guide.
Timber Flooring has been removed from E3/AS1 Acceptable Solution Amendment 7 and we have therefore developed an Alternative Solution for E3 which is suitable for the following;

Single-Dwelling Residential Homes

For kitchens, bathrooms, toilets, and laundries, you must specify our wood flooring in accordance with the Forté Timber Overlay Flooring System Installation Guide. This guide has been updated to include the application of wet area sealant during installation in wet areas in order to create an impervious surface as required by NZBC E3.

Multi-Dwelling Buildings 

For multi dwelling buildings, such as apartments, you must ensure kitchen sink overflows comply with requirements under 2.0.1(b) of E3/AS1. If this is not possible, then a wet area membrane must be specified beneath the wood flooring. You must also specify installation in accordance with the Forté Timber Overlay Flooring System Installation Guide. This guide has been updated with requirements to apply wet area sealant during installation in wet areas in order to create an impervious surface as required by NZBC E3.

2. Wet Area Membrane

Install a wet area membrane beneath the wood flooring

For bathrooms, toilets, and laundries in multi-dwelling buildings, you must specify a wet area membrane beneath the flooring. Please refer to the Forté Timber Flooring Overlay System Design Guide for more information.


Products that may not meet the requirements

When specifying timber flooring in wet areas, certain products are unlikely to meet the requirements as an Alternative Solution for the E3 clause. Examples include: 

Timber Floors with oil and hard wax coatings 

Timber flooring with oil or hard wax coatings may not satisfy the impervious requirements. These finishes are designed to be absorbed into the timber, allowing it to breathe, leaving minimal build-up on the surface. Therefore, we advise that timber products be specified with a Polyurethane finish which seals the surface effectively. 

Floating installation

Floating floors are designed to allow for the natural movement of timber, making it difficult to seal around the perimeter without causing issues. Therefore, it would be difficult to prevent watersplash from getting underneath the flooring. To meet the watersplash requirement in the Building Code E3.3.6, we advise the glue down installation method instead.
Note: Our Forté Timber Overlay System Installation Guide only includes a glue down installation method.

CodeMark certification

In an effort to streamline the council consent process, all our wood flooring collections have CodeMark certification, which guarantees that they meet the requirements of the Building Code. CodeMark is equivalent to an Acceptable Solution or Verification Method, meaning our wood flooring products are automatically compliant with the Building Code. 

Using CodeMark certified products streamlines the Building Consent Process, reduces RFI’s, and eliminates the chances of your council delaying consent in the submission stage. 


Guide to E3 Requirements

If you need more information or assistance, please reach out to one of our Territory Managers who can help walk you through the specification. Alternatively, download our Guide to the E3 Requirements. 



Visit one of our Showrooms

If you have any queries about our products or need help with your project, we can provide you with expert advice. Visit one of our showrooms or book a consultation with our flooring experts today.