Home Forums General Discussion Building permits for insulating walls.

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    This question arose from another thread ( Jo’s post about insulating her laundry walls) but I’ve started a new one because I think this is actually a different topic and I’d like some guidance.

    In Jo’s thread I asked a question about whether a building permit was required to insulate walls and the response (thank you Norman) jogged my memory about another discussion some months ago.

    Using the very useful SEARCH function (that’s a plug for the SEARCH function by the way) I found it. If you’re interested in the issue of insulating walls go back and look at the earlier posts – insulating walls without removing the linings. They are very informative and Adriana posted a really useful link to DBH guidance on building permit requirements (http://www.dbh.govt.nz/retrofitting-insulation-guidance) which I followed.

    My re-reading of those posts is that there is most likely a requirement for a building permit to insulate walls and that BCA requirements are different in different areas. Is that correct??

    I have to admit that in 9+ years I haven’t realised that (don’t worry I’m not out providing advice to people but I am thinking about policy and operational guidance quite a lot) and I would like some clarity from you well informed people.

    If we (the royal we that is) are looking for solutions to insulating walls and want advisors to be well informed this clearly needs to be taken into account.

    I’d appreciate any guidance people can provide.



    Christian Hoerning

    Hi Sally,

    That’s a great question and you can find the answer to it on EECA’s awesome Energywise website http://www.energywise.govt.nz/your-home/insulation/wall-insulation

    “Check local building consent requirements. Retrofitting wall insulation needs a building consent unless your local council has granted an exemption for this type of work. Either way, the work must comply with the Building Code. Find out about requirements through your local council.”

    For further in-depth information remember that EECA and MBIE have published a Guide for retrofitting wall insulation.

    Missing you here at EECA,




    Wonderful! Thanks Christian.

    I’m kind of stunned I never realised that. Its clearly (yet another) challenge along the path to retrofitting wall insulation that I hadn’t been factoring in. Thanks!

    Eion Scott

    You’ve every right to be confused Sally, it’s actually been a relatively new requirement, introduced as I understand in response to concerns about the weathertightness issues that might arise from retrofitting wall insulation, particularly in brick veneer clad houses. This is actually a fairly moveable feast, and while Christian is right that councils can set rules in this area, I understand that MBIE has given a determination in response to pressure from the supplier about whose system the concerns were raised and councils are no longer able to require a building consent for their system. This may well end up giving them a competitive advantage over other, possibly more reputable suppliers. I would be interested in hearing how other councils are responding. And a word of warning and an apology for being oblique, but this is a very litigious supplier so best to keep names at bay.

    Gleb Speranski

    Hi All,

    The only determination that I know of was issued by DBH back in 2011. Wall insulation retrofit guidance is available at this link … http://www.dbh.govt.nz/UserFiles/File/Publications/Building/Guidance-information/pdf/retrofitting-insulation-in-external-walls-guidance.pdf

    In the nutshell, the document explains that while building work associated with the wall insulation retrofit must conform to the Code, insulation products installed do not have to meet H1:

    The Building Code performance criteria listed below are the relevant provisions of the Code to consider when assessing retrofitted wall insulation and whether it complies with the Code. Other Building Code performance criteria may also need to be considered for the building work associated with retrofitting insulation. For example, removing and reinstating structural wall linings or drilling holes through studs would require compliance with the Building Code clause B1.3.1. However the insulation itself does not need to comply with B1.3.1 as it is not part of the structural system of a building.

    It is useful to highlight upfront that the R-value of the retrofitted wall does not need to comply with the Building Code clause H1 Energy efficiency. There is no doubt that insulation is retrofitted to improve the wall R-value, but from a regulatory point of view retrofitting insulation is simply an alteration of the ‘thermal envelope’ described in H1.3.1(a). Unless the cladding, framing and linings of the wall are also reconstructed it is hard to consider how the ‘thermal envelope’ has been reconstructed, which would trigger compliance with H1.3.1(a). Therefore, the energy efficiency provisions of the Building Code are not mentioned in this section, which lists the performance criteria that insulation retrofits must comply with.

    I was not aware of the MBIE determination and would like to find out more about it. Can you please provide a link to it?

    Kind regards,




    Thanks Gleb and Eion,

    Gleb, I will need to read H1 and B1 to fully understand this as I am not particularly family with this. But what this has done is highlight that its clearly not a straight-forward issue which I, somewhat naively, had assumed it was.


    Eion Scott

    There’s been a number of determinations, I’m not sure if they’re published, on injected foam insulation. There was a suggestion that as a result it would be included in exemptions from Building Consent listed in Schedule 1 of the Building Act. However, I’ve just been told that external wall insulation still requires consent, so scrap what I said above. However, we now have very few grounds to refuse consent, basically only for fire egress, disability access and that the building will operate at least as well as it did before the installation (in other words, that insulation levels won’t be worse) . That all sounds fine, and it’s reinforced by the Practice Note below, which outlines what mitigation measures we can require, such as measuring moisture content inside the wall before and after, but it means we can’t refuse the consent because of structural or weathertightness issues that were the original cause of concern with this product.  Hope that helps.


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