Hi Renee,

I have drafted this response to your question, with some consultation from my colleagues at Beacon.  Hopefully it will help you!

Regards,

Vicki

Walls are complex – they serve many functions beyond hosting your art! A key role is keeping out the weather: NZ construction these days generally uses a cavity system designed to allow any moisture that gets in to dry out.  So any changes you make to your wall system (such as adding insulation) has potential to alter the breathability of your walls and also the weather tightness of your home.  This is why many new wall insulation products such as the spray in foams are not favoured by BRANZ or the government.  In addition, you don’t really know what you have in your walls until you look!  Is there building paper  present (plays an important role in moisture management)? Is there already rot that needs to be remedied?  Are your electrical wires in good condition?

The best way to insulate walls, a great intervention to improve the performance of your home, is to remove the linings or the cladding and do it properly following the solution set out in NZS 4246:2006 Energy Efficiency – Installing Insulation in Residential Buildings.  Ideally you’d get good advice from a trained insulation installer (you only want to do this once and so do it right) on what product is best and how to install it to optimise warmth and the other weather tight functions of the wall.

Industry is looking hard at wall insulation, particularly in Christchurch, where relining or recladding of many earthquake damaged walls will ideally happen with wall insulation at the same time.  Industry is working on insulation installation training – research shows effectiveness is strongly related to how you’ve put insulation in.

Beacon’s research on the value of wall insulation would indicate that any time you ‘intervene’ in your wall, even simply painting inside or stripping wall paper, it is worth considering removal of the lining and insulating.  Once you have painted/relined etc. you are unlikely to disturb that wall again for a long time – a missed opportunity to improve the warmth of your room and bring down the price of your energy bills.

There is another technique being offered in Wellington by a company with a background in wall linings, plastering etc which can be described as ‘keyhole’ surgery. Here is what I understand. Holes are cut in intervals in the existing gib between the joists and the gib removed. Insulation is then inserted and the  gib replaced and re-plastered/repainted. This company is associated with a residential energy services company so will be well informed about the various other issues as outlined by Vicki. There are a number of interesting aspects to this method (1) the cut is made on an angle so it is relatively simple to fix the gib pieces back on (2) skirting boards, scotia etc are not disturbed so they are not damaged and (3) the issue of building permits as walls are being replaced does not apply. While this is not cheap and the final performance of the insulation may not be quite as good as taking off entire walls, it will cost much less.  Could be 80:20 both in cost and performance. I understand this company is looking to expand into Christchurch. I am not providing the company name as I am not aware of the hub proptocol in this regard. The organisation that really ‘nails’ retrofitting light timber frame walls will make their fortune. Regards, Norman Smith

Hi All,

As Adriana points out, the Building Act allows for exceptions. What I was hoping to explore was if and where in the country this method of retrofitting insulation into wall cavities would be considered to be exempt from requiring a building consent. If I understand correctly the principal driver of the requirement for a consent when replacing linings relates to their contribution to the structural integrity of the wall – remove the linings and its important to replace them with something of equal strength. So it seems to me the issue is this; if you are cutting modest sized, temporary keyholes and then replacing them would/could/should a BCA or similar waive the need for a consent?

Further, will this vary between councils and individuals, which could become an issue if this is going to become a method more widely used? Which I guess raises the next questions, had anybody heard of the keyhole method before I raised it, what do people think of this development, what will CENs say to people who approach them to ask about it?

Kia kaha, Norman

Hi Renee,

There is always more to tease out, but a good start on both this topic and the use of the Hub. Regards, Norman

Hi Adriana,

No problem at this end; there is much to be learned. I think you and I may be approaching this engagement from different perspectives,  which is invaluable at this start up phase of the Hub. Right now I am more interested in process rather than content – how are people sharing ideas, who is contributing, are all ‘stakeholders’ involved, where are the gaps, are most people just observing rather than participating and why, are they even tuned in yet? Have we even begun to scratch the surface of this discussion or has it been fully mined? Hence my open-ended questions seeking input from others. Having said that, content is very important to you every day at the coal face in Palmerston North working alongside other Council staff and industry. Is your experience the same or different from people in other parts of the country? How will we know? Ultimately the sum of the collective experiences should result in better practise and potentially feed back into operating policy of all Councils.

Cheers, Norman

In the case of Christchurch City Council building consents, the Council has advised that as long as the installation complies with NZS 4246: 2006 a Building Consent is not required (In practice this means a batt or similar product installed and building paper must be installed if not already in place- and if retrofitting from the inside this means stapling it into the cavity, as described in the standard).

In case people haven’t seen it yet, EECA and MBIE have just released a new guide on retrofitting wall insulation – with Christchurch in mind in particular.  In my view anyway, this is an improvement on the 4246: 2006 approach, and hopefully since MBIE has endorsed it, Consent Authorities will consider not requiring building consent for installations that comply with it.  The link to the new guide is: http://www.eeca.govt.nz/resource/guide-retrofitting-wall-insulation

Hi Paul and all…. is there a building scientist in the house?

The ceiling and underfloor are obviously where to start and staging the upgrade process by installing insulation there and experiencing the impact over the next winter is the way to go.

Your comment  “The ceiling and under floor will make the biggest difference” is an interesting one – hence my call for a building scientist. Once the ceiling and underfloor have been upgraded does this then make the walls and windows the weak points in the building envelope? I would think yes.

Agree with your comments about air ingress except in terms of cost effectiveness and benefit I would put it first, ahead of any insulation. Its one of those situations where everyone  says weatherising, yes, yes, but very few people do it thoroughly, even professional installers. It is just so UN-sexy. It also takes a surprising level of understanding of building construction and skills with caulking guns etc, and of course time.

It just so happens that for a ‘case study’ I am about to undertake a serious weatherising attack on an exposed house in Wellington where its not possible to install any insulation. We will be documenting in some detail, and perhaps making a short film, of what we do (I think people will be surprised) and then reviwing the impact.

In my experience I don’t think anythink quite like this has been done before. Also, and I may be wrong, while there are bits and pieces published  – e.g. http://www.beaconpathway.co.nz/files/docs/HomeSmart_Renovations_homeowner_newsletter_Mar09.pdf – I haven’t come across a comprehensive and illustrated resource covering all aspects of weatherisation. What have I missed?

Perhaps I should ask EECA to help produce this and put it on their website!
Cheers, Norman