Wall insulation

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Of all the potential improvements to Christchurch houses, we believe the greatest opportunity lies in installing wall insulation. Why?  Because it will make the biggest improvement to how the home performs and because the chance to do so doesn’t come around often.

It is an important piece in the house performance puzzle.

Wall insulation is the lesser known cousin of ceiling and under-floor insulation.  It’s not government subsidised (yet) and many homeowners don’t realise its importance.  However, research has shown that insulating only the ceilings and under floors will save a bit through using less energy but it won’t warm the house to a healthy level.  To reach the minimum temperatures recommended by the World Health Organisation for good health (16°C in bedrooms and 18°C in living spaces) AND save energy, wall insulation is vital. 

We’ve seen the benefits of including wall insulation in Beacon’s latest monitored home, the NZ Housing Foundation’s HomeSmart Home - warm enough not to need heaters, very low power bills for this low income family, and goodbye to the family’s asthma problems.   Even taking a purely economic approach, there is a  1.88 year payback period on insulating bedroom walls, and even utility rooms come out with a payback of less than 9 years.   See the Fact Bank below for more information.

The opportunity is huge and won’t come around again for a while.

There are two reasons that wall insulation is not often retrofitted to existing homes.  It’s costly - although the cost of the wall insulation and installation itself is relatively low, the cost of removing wall linings or cladding is significant.  And it’s inconvenient - generally, rooms need to be vacated while linings are removed, replaced, gib-stopped and finished.

For these reasons, wall insulation is often only undertaken during major renovations, a once-in-30-year event. There are an estimated 3,300 renovations normally undertaken annually in Christchurch where re-lining of plasterboard in walls occurred.

Compare this to the number of homes awaiting repair: 110,000.  Many of these homes have damaged cladding or internal linings, which will be replaced as part of the earthquake repairs.  A golden opportunity indeed!  And given 63% of Christchurch’s homes were built before insulation was mandatory, most of these will have no wall insulation whatsoever.

What’s being done? 

The Department of Building and Housing has issued guidance for retrofitting wall insulation, and Christchurch City Council has waived building consent for segment-type insulation.  Insulation manufacturers have been looking at wall products which will make installation easier, and processes to fit within insurance protocols.

EECA and MBIE have prepared a “Guide for Retrofitting Wall Insulation”.  This guide provides best practice guidelines for retrofitting the most common types of wall insulation (blanket, segment, rigid and semi-rigid sheet) into framed external walls of existing houses.  It is available online here:

The Insulation Association of New Zealand is running training sessions based on the Guide, which installers will need to do in order to do wall retrofits on EQC repair projects. 

Beacon has assembled a fact bank (below) with the latest research on why wall insulation is needed and data on the opportunities presented by earthquake repair.

  • 30-Apr-2012 (Publication BBS/2)

    Retrofitting Wall Insulation Fact Bank: Benefits and the Opportunity Earthquake Repairs Offer Christchurch (PDF 56KB)

    Lois Easton, Andrea Blackmore

    This fact bank is the repository of Beacon's core facts and knowledge about retrofitting wall insulation and the potential for this to be undertaken during earthquake repairs in Christchurch.  It reflects our current knowledge - if you have other or more up-to-date information, we invite you to draw our attention to it.  We will hold the fact bank as a living document and issue updated version as we receive feedback and input.  

CEA installer

Community Energy Action installer working on Huntsbury 2 wall insulation retrofit

Logo, BBS

Living in Christchurch?

Make the most of the new Build Back Smarter Service

Christchurch   City Council has launched a free service for Christchurch people   rebuilding or repairing their earthquake-damaged homes to provide   advice about insulation,  heating methods and energy saving measures   such as double glazing,  ventilation and lighting.

Homeowners   can contact one of the service’s assessment providers who will prepare a   healthy home improvement plan tailored to the needs and budget of the   home owner.