Every country has its fair share of bureaucracy – paper trails, formality, policy and legal protection. Embedded in many of our newsletters are also the cries of frustration from residents and community groups who constantly face the mountain of words that impede any real forms of action. We have even gone as far as describing the effects of processes and their control on agencies and how this disempowers, demoralises and generally creates eunuch agencies. Simply, agencies are forced to silo themselves, keep separate, protect their back doors from others and maintain a safe distance of inertness.
What happens when enough of the people in those agencies realise this is the case?
- Do they leave?
- Do they complain to their colleagues?
- Do they complain to their friends, family and pets at home?
- And/or do they ALL just wait for someone else to fix the problem?
That’s what’s been bouncing around in our heads this week… The question it really comes back to is:
How is it that everyone can see where the issues are in the residential recovery and yet still believe it is not them that can make the change?
Heading towards the end of the year is the time when we should all be reflecting – CanCERN is always reflecting so it’s not new for us – but the end of the year is also the time to summarise where things are at. This, as evidenced by the initial rant above, is a frustrating time and there are a few critical comments and questions that need to be said. We are gathering our thoughts so they are a little less rambling so stay tuned.
Defining ‘as new’ – Southern Response video
We stumbled across this video the other day and thought it might be helpful for some. It covers how Southern Response defines ‘as new’ – a topic of constant debate. Below is a link to the video itself as well as a bit of comment from Southern Response.
https://vimeo.com/103401206
‘As New’ Definition
A key concept in the premier house policy is rebuilding or repairing your house to an “as new” condition.
“As new” is not defined in the AMI premier policy so we interpret it within the context of the policy as a whole, the Building Act, and using knowledge gained from legal judgements including the recent High Court decision in Turvey Trustee Limited v Southern Response.
The starting point is that the rebuilt house or repaired item needs to be equivalent when compared to the original. This does not require a direct replacement.
To decide what is equivalent involves taking into account things like the size, functionality and relative quality of the original. There also needs to be a reasonable recognition of the character and appearance of the original.
Work needs to be carried out using today’s standards and methods and must comply with relevant building legislation and rules (including the building code).
Where items have a structural function it is their structural performance which is the consideration.
Where items have an aesthetic function, current reasonable concepts about the way those finished items look is relevant.
For repairs, the focus is on the item that has been damaged and is being repaired.
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Damp-proof membrane Q&A
Last week we posted about ‘repairs to holes in damp-proof membranes’ following a few questions from residents. Below is the original post along with a follow up question and answer. Hopefully this post sheds a bit of light on things, and if you have any further questions, feel free to ask them in the comments section – we may not be able to keep going back and forth getting answers forever, but we’ll do our best to address the major concerns. A big thanks to geotechnical engineer Jordan Walker for taking the time to read and respond to residents’ queries.
Repairs to holes in damp-proof membranes
There has been a bit of talk recently (and over the past few months for that matter) about damp-proof membranes (DPMs) and how they’re fixed if broken during repair work. We put the question below from In The Know to Jordan Walker, a geotechnical engineer who’s appeared recently on the Covered TV series. If after reading his response you have follow up questions, comment below or send an email to marcus@cancern.org.nz.
Here’s the In The Know question that’s awaiting an answer from MBIE:
If holes are drilled through a concrete slab and through a damp-proof membrane, how is this repaired?
If holes are drilled through a concrete slab and through a damp-proof membrane under the concrete slab and grout is pumped into it:
- how do they fix the fact they have now punctured the damp-proof membrane under the concrete slab, risking moisture seeping into the house?
- how is a punctured membrane under the concrete the same as “as new”?
And here’s Jordan Walker’s response:
This can be a challenging question and something many people misunderstand. The purpose of the DPM is to satisfy Clause E2 of the Building Code regarding External Moisture. The objective of this provision is to safeguard people from illness or injury resulting from external moisture entering the building. Typically, where a slab on grade foundation/floor is used, the use of black bituminous or polythene is used to satisfy the requirements of this clause. However, where it is not possible to install a DPM (i.e. for cast-in-situ concrete walls or similar) then the concrete itself will need to be watertight and the engineer or designer will specify this based on DPM requirements set out in NZS4229, Section 7 (unless specifically designed).
Generally, black polythene is a cheaper material to use than concrete additives to achieve a waterproof solution. Therefore, for new builds, the person commissioning the building will choose the cheapest suitable product over an expensive additive which achieves the same result.
When re-levelling concrete floors there are typically two common methods used:
- Mechanical lift of the slab (e.g. SmartLift) with the use of Grout to fill in any voids after the floor has been lifted, or
- Grout/Resin injection under the floor to lift the floor using the pressure of the grout (appropriate for minor levelling of generally less than 50mm, but can be used for greater heights subject to specific design)
For the first method, access points are cut into the concrete floor of typically 300mm x 300mm to allow positioning of the jack. Such a sized hole allows repair of the DPM in accordance with NZS4229, C7.4.5 (i.e. by taping, or the use of wet applied damp-proof membrane material or by other means appropriate to the type of material).
For the second method, smaller injection ports are cut into the concrete (less than 20mm diameter) and a closed cell polythene additive is added to the grout or resin which resists moisture penetration in a similar manner to the black polythene (ie the grout/Resin itself provides the waterproofing qualities). For this type of work, the installer will issue their own design (and accompanying producer’s statements) and sign off on the work as well (i.e. issue the PS4). This means that the owner can have certainty that if anything does go wrong, the installer will fix.
It should also be noted that in the normal course of constructing dwellings, minor penetrations of the DPM occur (i.e. with reinforcing steel, service connections, or accidents) and are fixed prior to the concrete being poured. Where these minor penetrations occur they are repaired (if noticed), but many will pass through the inspection process unseen. However, as these are very minor in nature, they typically go unnoticed over the life of the dwelling; or only become apparent after many years of moisture build-up (i.e. 20+ years). In fact, on some sites, it may be possible to not install the DPM if, after specific design, the engineer deems it unnecessary (i.e. where there is sufficient separation from external moisture to reduce the risk of it entering the dwelling or where a watertight concrete is specified).
There are of course exceptions to the above, but these would be dealt with on a site by site (i.e. specific design) basis.
Jordan Walker:
Senior Geotechnical Engineer/Engineering Geologist
BScGeoEng, MIPENZ, CPEng, IntPE(NZ), PEng (APEGNB – Canada)
Follow up Q&A
Resident Question
Firstly, thank you Jordan Walker for your informed and researched answer. From the answer: “This means that the owner can have certainty that if anything does go wrong, the installer will fix.” …”they typically go unnoticed over the life of the dwelling; or only become apparent after many years of moisture build-up (i.e. 20+ years).” Therefore by the time you find out your home is a leaky building with rising damp through the floor your insurance company will say “prior damage” or “existing damage” .. and it is their cheap “solution” which caused the problem. This cheap solution is obviously not as good as new. For example before the slab is poured there can be an inspection looking for holes .. with a “second hand” slab that has been through 12000 earthquakes and I believe has probably reached its “mean time between failures” if there is a similar measurement for floor slabs .. then there is no ability to check if that second hand floor slab has other cracks and holes underneath it which will affect its ability to do the job and also keep moisture out of the home. a second hand floor slab can never be as good “as new” logically. So the risk is being put onto the homeowner for any mistakes in the “repair” when it should be on the insurance company. A new floor slab would be “as new”. An old one which has been patched up and where the risk is now on the repairer and or the homeowner for the next 50 years is not.
Jordan Walker’s response:
My understanding is that if Council does not require a Building Consent, then there is no requirement to upgrade the foundation system unless it can be found to not be Code Compliant. Even then, as the Consenting Authority, it is CCC’s discretion on whether they accept the works or not. Provided the repair strategy includes provision for repair to the damaged DPM, then the repair strategy will be suitable. It is not appropriate to assume that the installer/repairer will not do their job (which is what your reader is assuming with their statement). The obligation of the insurer is to repair EQ damage. If a homeowner thinks that damage not included in a Scope of Works is in fact EQ damage, then they can engage their own professionals to provide evidence to support that. This is not to mean a report by an engineer stating that the “DPM may be compromised” will be sufficient, since this is not an engineering certainty. It would require an invasive inspection to confirm damage to the DPM. Provided the insurer accepts that evidence, then the insurer is then obligated to undertake the additional works and all costs associated with that work. However, if the investigation finds that the damage is not in fact caused by the EQ, but a result of, say, installer error, then any works associated with the investigation and repair would be at the owners own cost.
I should also add that as per table A4.1 in the MBIE Guidelines cracks in concrete floor and perimeter foundations of less than 1mm require no repair. Between 1mm and 20mm they require repair by either epoxy or grout injection, and greater than 20mm they require break out and recasting. My interpretation of this is that cracks less than 1mm are unlikely to have compromised the DPM. Between 1mm and 20mm there may be damage to the DPM, but the repair solution is by epoxy or grout injection which effectively replaces the DPM. Greater than 20mm, we need to cut it out and recast and this would also involve replacement of the DPM.
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Covered episode five
Covered episode five is online! What’s up this week:
- Southern Response on their progres
- EQC on complex land issues including ILV and IFV
- The different types of foundation repair methodologies with a geotechnical expert
Segment 1 – Southern Response Progress
http://www.rebuildchristchurch.co.nz/…/covered-episode-5-se…
Southern Response Earthquake Strategy Manager Casey Hurren explains progress on settling their remaining 3,500 insurance claims, the complications with multi-unit buildings and the importance of communications in the settlement process.
Segment 2 – EQC Talk Land Issues
http://www.rebuildchristchurch.co.nz/…/covered-episode-5-se…
Keith Land, the Earthquake Commission’s Head of Canterbury Land, talks to Covered about Increased Liquefaction Vulnerability (ILV) and Increased Flooding Vulnerability (IFV)
Segment 3 – Foundation Repairs
http://www.rebuildchristchurch.co.nz/…/covered-episode-5-se…
CanCERN’s Marcus Irvine talks foundation repairs with Cook Costello geotechnical engineer Jordan Walker, specifically Type A, B and C foundations, jack and pack and how engineers work out the best way of putting floor levels back to a usable state.
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Quake TV series for kids – episodes online
HiViz – the low-down on the Christchurch rebuild is now live on the Future Christchurch website.
Made by kids, for kids, each episode features interviews with the movers and shakers of post-earthquake Christchurch. They give a good overview of what’s going on, particularly in the central city.
Click here to see all six episodes.
Launched this week: Episode 6, the Margaret Mahy Family Playground special ‘State of Play’.
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