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

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This article provides information about the November 2020 change to E3/AS1 and provides guidance on how to gain compliance and submit an alternative solution for wood flooring in spaces with sanitary fixtures and appliances.


From 5 November 2021, additional Building Code changes come into effect which impacts how wood flooring is to be specified in wet areas. This change is only relevant to timber flooring being specified in wet areas such as kitchens, bathrooms, toilets and laundries, and does not include living areas, dining spaces, hallways or front entrances.

We have had in-depth discussions with MBIE, Auckland Council, BRANZ, Masterspec, the waterproofing association and the Australasian Timber Flooring association to gather information and put together a simple but effective specification that meets the new building code requirements.  

Going forward, to minimise delays or RFI's (request for information) from council, we recommend that all projects being submitted to council should include the Forté Timber Overlay Flooring System PTS in the consent documentation. 

To assist specifiers with this change we have updated our Timber Overlay Flooring System, and the relevant documentation, to ensure it aligns with the new requirements. Our team will continue to meet with architects, designers, builders and our approved installers to implement the changes and ensure we have the support in place to manage the change.   

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 website.

If you’d like to learn more, please book a virtual or face to face education session by contacting your Territory Manager at the bottom of this article. 


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 (Kitchens, Bathrooms, Toilets, and Laundries)
    Specify installation 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.

    Kitchens in Multi-Dwelling Buildings (e.g., Apartments)
    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.
    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 (e.g., Apartments)
    A wet area membrane system must be specified beneath the area where the timber flooring is to be installed. Please refer to the Forté Timber Flooring Overlay System Design Guide for more information.


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. While kitchens are the most popular area for installing wood flooring, the upcoming change to the amendment will see flooring surfaces under the Acceptable Solution 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. 


When specifying timber flooring in wet areas, the below products are unlikely to meet the requirements in order to achieve an Alternative Solution for the E3 clause of the building code:  

  • Timber Floors with oil and hard wax coatings may not satisfy the impervious requirements. Oil finishes are designed to be absorbed into the timber, allowing it to breathe, which leaves a minimal build-up of coating on the surface. We therefore advise that timber products be specified with a Polyurethane finish, which seals the surface, as opposed to an oil finish which does not. 
  • We advise to specify a glue down installation method as opposed to floating. Floating floors are designed to allow for the natural movement of timber, making it difficult to seal around the perimeter without causing issues. It would therefore be difficult to prevent watersplash from getting underneath the flooring which is a requirement in the Building Code E3.3.6.
    Note: Our Forté Timber Overlay System Installation Guide only includes a glue down installation method.  

Forte is currently working on a codemark which will streamline the specification process, in the meantime please use the information in this article as guidance to gaining compliance and putting forward an alternative solution. If you need more information or assistance, please reach out to one of our Territory Managers who can help walk you through the specification.

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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.