Blown in Wall Insulation

[Adam Reid]

Hi Everyone,
I was wondering if anyone can comment on blown in dry fibre wall insulation? My understanding is that any type of retrofit wall insulation needs to have building paper installed to prevent moisture transfer, and is therefore only practical if the wall linings or cladding are being removed. Injected Urea formaldehyde foam was something clients were urged to avoid. However, the company below has been operating for a few years now. They are apparently codemark certified, claim to be able to get building consent from council and no building paper is required.
https://insulmax.co.nz/
Is this too good to be true? Is it safe to recommend this product or should we be sticking to the old adage that building paper is always required?
Any feed back appreciated.
Thanks
Adam

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[Vicki Cowan]

Hi Adam
nice to read you, I’ll send to a couple of building scientists and see what they say.
I hope all is well in your bubble, Vicki

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[Adam Reid]

Thanks Vicki,
all good here in ChCh. Thanks to the lockdown I finally have enough time to post my questions to the Hubosphere! Hopefully a few more of our brethren might take the opportunity to spark some discussion.
Adam

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[Vicki Cowan]

Hi Adam and all others watching in,
I have been having a bit of a chat online with Roman Jaques at BRANZ on this to see where the research is. Here’s his reply to me…. So look for that upcoming report and understand the points he makes about liability.
Cheers
Vicki

Here is the BRANZ response:

We have just finished a research project looking at the topic of retrofitted blown glasswool insulation. The research report from that project SR436 Linings on retrofit insulation in weatherboard walls – Ensuring effective water management, is about to be published so watch this space. Some points to note however:

Councils issuing consents is a given because of the Codemarks.

In most cases the councils treat the installations as being consent exempt, but the installer still has to apply for the consent on behalf of the homeowner. Councils do not need to get involved other than to have on file that the codemark was referenced in the consent application and note if the particular installation is deemed consent exempt. That way the liability rests with the certifier and not with the council.

Councils generally don’t do any inspections or follow-up or (more importantly) issue code compliance certificates, so homeowners shouldn’t consider the consent as an indication that a council is doing anything other than confirming for their insurers that the process of determining if the house is suitable for the product and the responsibility for the outcome rests with the homeowner, the installer, and their certifier.

Hope this is useful.

Roman

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[Adam Reid]

Thanks Vicki and Roman,

I look forward to reading the report.
Some interesting points there regarding building consents. I think most homeowners (myself included) think that building consent and code compliance go hand in hand but this is not necessarily always the case. Food for thought.

Cheers

Adam

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