Glass bought her West Melton bungalow in 2014. On the stony ground of the rural outskirts of Christchurch, with a clean property report and no visible cracks in its Gib, exterior walls or marble kitchen floor, it seemed a safe bet, she says.

But in July, she was getting the en suite bathroom freshened up. "I was thinking we might stick the house on the market in spring and move back into town again."

The carpet fitter discovered a lacework of cracks in the concrete slab floor. Now Craig is here to check over the whole house properly.

With a metal sounding pole, he taps his way across the carpet in the living room methodically. It rings solid near the walls then gives a tell-tale thud towards the middle. Glass says even her lay ears could pick that up.

A small square of carpet is removed, revealing a ragged fracture wide enough for Craig to wiggle a finger in.

As he half-expected, the foundations were built without wire mesh reinforcement – a shockingly penny-pinching practice Christchurch building codes allowed right up until the earthquakes.

So no surprise the concrete slab shattered, even if the broken pieces have stayed pretty much in place.

To find out how bad it is, Craig drills a hole alongside the crack. The long snake of an inspection camera is poked down into the sand and stone sub-base. He invites Glass to take a look.

Craig has warned the worst damage is often buried out of sight beneath the concrete itself. Quakes can churn up the sub-base, leaving the slab floating above a void.

Again, cheapskate building practices didn't help Christchurch, he says. Where Auckland uses crushed quarry rock that is strong and triangular – more likely to stay locked in place – the South Island fills its foundations with local greywacke river stone, cheap and abundant, but also soft and round. A material that shatters and slides.

"You can imagine in an earthquake, all these smooth river stones get shaken up. The fines, the sand, also wash away. The slab on top can't follow and so voids are created," Craig explains.

In Glass's case the slab did crack. But Craig is finding houses where the deeper problems remain completely hidden. Especially where the land is soft and damp.

"The sub-base can carry on repositioning itself. So the void will be growing bigger and bigger until finally the slab can't take it anymore. You get a bang, a dishing of the floor, because the walls were the only thing keeping the slab in place."

Through the scope, Glass can see the cavities Craig refers to.

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And there it is. One minute, the proud owner of a smart home with a ratings valuation of $1.27 million. The next, not knowing quite where you are.

Glass says it is not as if the Earthquake Commission (EQC) never assessed the property. Records show a claim was settled after the quakes – for a buckled garage door.

Now her house could be a tear-down. Or at the very least, Craig is warning the broken floors will need to be excavated right down to the sub-base and rebuilt.

THROWING ANOTHER $1B AT THE CITY

It is worth repeating. Greater Christchurch is nine years on from the Canterbury earthquake sequence. Yet so many homes may still rest on unacknowledged foundation damage.

Paul Finch, a Rangiora engineer and project manager, and David Townshend, a Christchurch property investor and member of the EQC Claimant Reference Group, say Craig is right. The problems are way bigger than anyone wants to admit.

Townshend says look at the latest payments the Crown is having to dish out – about $1 billion to cover "re-repairs" and "on-solds". "Those are mostly about foundation issues coming to light."

Re-repairs is Christchurch jargon for all the houses EQC supposedly fixed under its Fletcher Construction-run building programme.

Townshend says EQC thought it could patch properties – keeping them under its $100,000 insurance cap – by "jacking and packing" foundation piles or levering up the corners of a slab.

However, a broken foundation will keep moving. So EQC had to set up its re-repair programme.

In 2016, that was supposed to cost around $60m. Now the official projection has reached $640m, with much work still to be done.

Then in August, there was the surprise news of a $300m fund to sort out the on-solds issue – houses with unaddressed damage that have now changed hands.

"The new owners were finding their homes were never repaired properly – either never actually touched, or the repairs have failed and are still moving," Townshend says.

It has become clear the houses are over-cap. They need to be lifted and the foundations replaced, or else demolished and rebuilt entirely.

But because of the failure to diagnose this before the six-year statute of limitations on insurer liability passed, the full cost has fallen back on EQC.

EQC was on the eve of a High Court test case it was expected to lose, says Townshend. The Government wound up with little choice but to spend another $300m of taxpayer funds to settle things before EQC's methods came under harsh legal scrutiny.

However Townshend points out that the on-solds deal is only a narrow settlement covering 1000 or so faulty properties handed on to unwitting buyers through recent house sales.

The ex gratia payments are also strictly time-limited. Homes bought since August will no longer be covered. And existing owners only have a year to discover they have damage and stick in a claim.

So Townshend says another way of looking at this $1b of extra spending is the Government is doing what it takes to finally shut the door on a couple of outstanding liabilities – two scenarios where EQC has been found out and was legally exposed.

But what of all the other houses in the city, Townshend asks? What of Craig's claim the recovery failed to identify foundation damage in thousands of homes?

Finch says this is where Christchurch needs to wake up. After nine years, you would think people would understand that with the way it shook, and the weakness of many of its building standards, its foundation problems simply have to be widespread.

Yet every week there are still home-owners waking up to the fact that while it may take time, eventually – and expensively – buried trouble will to find its way to the surface.

THE GAME OF CLAIMS

Finch and Townshend are speaking out because this year there is a public inquiry into the actions of the EQC conducted by Dame Silvia Cartwright. A possible chance of justice.

Like others – such as Underfoot's Craig and members of the claimants group, EQC Fix – they believe Greater Christchurch was put through a cut-price recovery.

Home-owners have been left with many hidden problems because an insurance process was created that did its best not to look too deeply for foundation damage.

It was a systematic oversight, they say. And through an exhaustive campaign of Official Information Act (OIA) requests leading to a submission to be put to Dame Silvia's inquiry, the pair have been tracking how the game has continued right up until the present day.

The basic story is well enough rehearsed, says Townshend. The Press covered it extensively.

Right from the first September 2010 earthquake, the insurance industry was worrying it might be bankrupted by having to meet its standard "repair to as new" home policies.

It stood to reason that pretty much every house in Greater Christchurch would have cracked or settled a bit. An "as new" policy was like standing there with an open cheque-book.

So there was a motivation to draw a line as to what amount of foundation damage actually counted – what affected the performance of a home structurally?

EQC was then in its own position of wanting to defend an interpretation of the EQC Act where it only in fact needed to get houses back to "as was" – their effective condition on the eve of the quakes.

Thus even before assessments, there was a two-step game where, if EQC felt it could handle foundation damage under-cap – under the first $100,000 that was its responsibility – its lesser standard would apply and insurers would be saved from their own more gold-plated commitments.

Townshend says to get ahead of the coming claims battle, EQC formed an Engineering Advisory Group (EAG) headed by Wellington consultant Dave Brunsdon, of the Kestrel Group.

The EAG was given the job of drawing up a manual of guidelines for the rapid scoping of building damage and also advising on the cheapest methods of repair that could satisfy the Building Code.

But control of the EAG was then quickly handed over to a separate government agency, the Ministry of Business, Innovation and Employment (MBIE), responsible for housing standards and the Building Code.

"EQC obviously realised that as itself an insurer, it couldn't put out such a document under its own name."

So MBIE was there to offer the assurance of independence when it came to defining the minimum level of earthquake repair insurers would have to achieve, Townshend says.

Yet a paper trail of internal emails now shows how cynically the exercise unfolded, he believes.

Townshend says logically, the proper way to assess earthquake damage is ground up. If the land has moved, drains and foundations ought to be checked first.

They are the expensive problem. There is not much point worrying about the house above if the damage below is not addressed.

However putting its name to the EAG-drafted advice, MBIE produced a guidance document, "Repairing and rebuilding houses affected by the Canterbury earthquakes", which approached the scoping from the top down.

The focus was on cracked walls, split Gib, tilted floors and other above-ground evidence a house was quake-affected.

As reported widely at the time, says Townshend, EQC's assessors did not make a habit of lifting carpets or crawling about under houses. Foundations were presumed sound unless the damage was too obvious to ignore.

The get-out clause was always that MBIE's guidance was just that. It provided rules of thumb to tell if building damage was structurally serious enough to leave a home in breach of the code. And then, what kind of basic repair could bring it back in line with code.

As MBIE's fine print stressed, the guidance did not replace any larger insurance policy promise about a house having to be returned to "as good as new".

However – as EQC Claimant Reference Group members can attest, says Townshend – back in the real world, the guidance was often employed as an argument that this was what the "experts" considered a serviceable earthquake fix.

So it was as much as a home-owner should expect – especially given providing an entire city with "as new" foundations would soon bankrupt the recovery effort for everyone.

COUNTING CRACKS

It might have worked. The belief was that above-ground damage should give a reasonable picture of a property's below-ground structural integrity.

Operating under MBIE's guidelines, EQC's assessments would weed out the more minor foundation problems – like a sunken foundation pile or crack in a slab – which could be patch-repaired for under $100,000.

Insurers would be saved the full cost of an over-cap claim being triggered.

But Townshend says the MBIE approach did not allow for Christchurch's history of poor building practices. And as well as such things as slabs without reinforcing mesh, there emerged a general issue with "rubble" ring foundations.

Underfoot's Craig was the first to ring an alarm bell about these. Arriving to inspect houses after the quakes, Craig soon found most pre-1970s Christchurch homes were built on piles with a ring foundation.

However these concrete perimeter walls were often constructed using any old material as aggregate, the local soft river stone, but also lumps of broken concrete or bits of brick. Craig says they frequently lacked steel rod reinforcement.

The older they were, the poorer the construction tended to be. "Any kind of building rubbish [was] tipped into the foundation trench," he says.

Before the earthquakes, even a rubble foundation could hold a home up. But after the tremendous violence of the February 2011 earthquake especially, Craig was finding many had been left shattered and spalled inside.

Chip off the mortar veneer and the concrete behind was often "just exploded".

But in January 2013, MBIE had come out with its guidance for dealing with "Type B" perimeter and pile foundations.

The recommendation was that localised cracks of less than 5mm could be pretty much ignored – just filled cosmetically and given a dab of paint.

Larger cracks could be repaired by injecting epoxy resin – a newly available solution which EAG structural engineers said would be strong enough to restore full functional strength to a perimeter wall.

When it sets, epoxy is in fact tougher than concrete. And being liquid, it could be pumped into a gap in minutes.

So it promised to be an extremely cost-effective way of gluing a cracked ring back together. And a cheap fix for cracked concrete slabs too.

With the blessing of MBIE's guidelines – Townshend says internal emails describe them as a "circuit-breaker" – EQC set to work epoxying foundations and saving insurers from sticky conversations about what "as new" might mean.

But Townshend – dealing with repairs to his own seven rental properties – says with a rubble foundation, cracks can run everywhere out of sight. As Craig says, the concrete is shattered.

And yet the top-down assessment approach meant EQC staff were simply making counts of particularly visible cracks rather than considering foundations as a whole.

Even having a size threshold – where a 5mm crack qualified for epoxy, yet a 4mm one didn't – made no structural sense, Townshend says. "There's still an air gap. It doesn't join."

One of his properties had 29 cracks in its ring. But as all were under the 5mm threshold, it was dismissed as having no real concerns.

However even more insidious was how the wording of the guidelines let EQC limit its scopes to just isolated sections of a ring foundation.

Townshend says a ring foundation is meant to function as a single continuous concrete beam, spreading its load across the whole footprint of a house. But EQC was dealing with unreinforced rubble perimeters likely to be broken by hairline fractures all along their length.

Under the guidance, it was permitted to glue a visible crack and ignore the rest. Or if epoxy couldn't bind a cracked area, perhaps cut out a section of the bad concrete and replace it.

So because the process didn't start with a full engineering assessment of the ring, Townshend says you would wind up with a property sitting where it was on loose footings – a few patches rebuilt to Building Code standards, but most of it still a code failure.

Hardly what the MBIE guidance was meant for. Give it a few years, and the fact nothing was actually fixed is going to show, Townshend says.

THE EMAIL TRAIL

What happened with Townshend's rental properties happened with many earthquake claims.

Townshend and Finch say a failure by the EAG to understand the realities of Christchurch construction standards, coupled to EQC's desire to keep claims under cap, led to a systematic under-assessment of damage to building foundations.

The guidance is the critical link in the story. And so the pair have been pursuing the internal tale of how it was formulated, as told in a dossier of emails and letters flying between the EAG, MBIE and EQC.

Finch says there are two important questions. Why didn't the EAG seem to know about the rubble issue? And what did it do after it found out?

The three key EAG members working on the foundation guidance were Kestrel's Brunsdon, Graeme Beattie, then principal structural engineer of BRANZ, and Mike Stannard, then chief engineer at MBIE.

Craig was talking widely about the difficulties of repairing rubble rings by 2014. Yet even in mid-2015, Beattie was writing, "We are trying to get to the bottom of what 'rubble' concrete is". Stannard echoes, "I still don't understand what rubble foundations are."

The EQC repair programme was, of course, several years under way. Finch says to get a grip on matters, MBIE's William Whewell was sent to Christchurch to investigate why so many EQC repairs were failing.

This Canterbury Earthquake Damage and Repair (CEDR) study demonstrated that guidance-endorsed techniques like jacking and packing – inserting spacers to level the floors of ring foundation properties – couldn't last because the rubble concrete was too fragile.

Whewell reported back to Beattie and Stannard of builders struggling to find sound bits of perimeter to attach fixings to.

"The walls are incapable of taking a percussion drill, let alone drill a dowel hole. On one property, the wall had been chased for double the original length without achieving a dowel hole."

STUNNING ADMISSION

Finch says this shows that by late 2015, MBIE knew why rubble was a problem. Yet nothing further was done in terms of the guidance and the issue left to lie for the next couple of years.

Then, in 2017, a Christchurch law firm was readying a High Court case against insurer Southern Response and its engineer decided to ask MBIE directly how the guidance could even be applicable to rubble-type foundations.

Dennis Monastra, an MBIE compliance spokesperson, consulted with Whewell as the in-house expert and replied the 2013 advice "does not apply to weak or oversize aggregate concrete". 

It could only apply to foundations with concrete conforming to a modern Building Code standard like NZS 3604.

Finch says this was a stunning admission that rapidly circulated among engineers in Christchurch in late 2017.

It appeared to mean that when it came to rubble, insurers couldn't even start to use the MBIE approach to scoping and repair. A full structural investigation would be required from the outset, likely triggering an over-cap insurance claim in many cases.

The email trail then shows Southern Response's own engineers soon double-checking whether Monastra's answer was officially sanctioned. And shortly after that, EAG's Brunsdon writing to MBIE bosses, saying there needed to be a public clarification.

EQC's research chief, Dr Hugh Cowan, was also emailing, urging a better answer on rubble. Eyebrows were raised at that. "Do you think this has been sent unprompted?" remarked one MBIE staffer.

The correspondence shows that pressure for some kind of retraction was building through April and May 2018.

Dave Robson, MBIE's building performance manager, writes: "I thought we had closed the lid on this can of worms? … I'm happy if you think we need to do something for EQC. Let me know."

Eventually Brunsdon, with the EAG's Beattie and Stannard, did draft a correction, issued in June 2018 as Update 10 to the guidance.

This said while the guidance didn't offer a specific repair solution for rubble foundations, it did contain information – like the uses of epoxy – which might be helpful.

The update added that while the original guidance was aimed at NZS 3604-qualifying construction, that did not mean it was narrowly tied to a foundation type or concrete specification, just generally to "one- and two-storey timber-framed dwellings".

Thus in retrospect, rubble could be deemed as having always been covered by the intent of the advice the EAG produced.

Finch and Townshend's expressions tell what they think of this. Clearly, they say, an unwitting Monastra gave an honest answer. Since then, MBIE has been indulging in verbal gymnastics to avoid its foundation guidance unravelling.

MBIE, for its part, would not comment directly on the email evidence gathered by the pair, nor on the incongruity of advice being found to apply to a type of foundation damage it had been unaware of.

It would only restate that the guidance was always intended to apply across a "continuum" of foundation types, and repeat that its sole purpose was to "develop repair solutions" that would be acceptable under the building code.

The usual question of whether a proposed fix then achieves the promises of a home-owner's insurance contract had to remain a matter of separate professional advice.

But for Townshend and Finch, the episode just illustrates the pressure to hold the line when it comes to assessing Greater Christchurch's earthquake damage.

ALARMIST TALK?

As it happens, Townshend and Finch are not the only ones collecting the evidence of internal emails and pushing for a full investigation of the foundation assessment question.

Claimants' group EQC Fix – represented by Mel Bourke, Cam Preston and Jake Preston, who works with Craig's Underfoot Services – is making a series of similar submissions to Dame Silvia's inquiry.

Bourke says talking about unaddressed foundation damage is an uncomfortable subject. Many Christchurch home-owners are still in denial, not wanting to risk their property values by making waves about the systematic under-scoping of the city's housing stock.

And that attitude continues to play into the hands of EQC and the insurers.

"People say, oh, my house wasn't that flash to start with. There's a few cracks, but I had some cracks before."

However Bourke says owners are also realising Townshend and others must be right when they say buried trouble will eventually surface. Unfixed houses will keep moving.

And seeing the scale of the settlements for re-repairs and on-solds will be spooking people now, she says. It shows just how much money is involved once any part of the foundation question is honestly faced.

So what about Craig's guesstimate there may be tens of thousands of homes at risk of unacknowledged earthquake damage?

Is this simply alarmist talk from someone making a profit from acting for claimants, as detractors might suggest?

Craig – who in fact worked with EQC after quakes in Palmerston North in 2003 and Te Anau in 2004, and helped research foundation performance – says his figures just follow from the severity of the event.

By his reckoning, Christchurch has some 56,000 pre-1970s homes highly likely to be sat on rubble perimeter rings. We know all about the under-scoping there, Craig says.

Now, in addition, there is the widespread problem he has identified with slabs and their sub-bases. And here the issues have remained even more concealed than they were with rubble.

Craig says the MBIE guidance made assessors focus on surface cracks. However, if it is the underlying river tailings that have been shifted about and left voids, the damage beneath could be considerable.

"You can imagine what happens in an earthquake if all your sub-base suddenly disappears and your slab is going up and down like a diaphragm on a drum."

Even wire in the concrete wouldn't save the floor, he says. "The cracks you can see on the top might be hairline and cosmetic. But if you could go under the slab and look, the cracks could be 10 times bigger."

Craig says Christchurch would have about 40,000 properties with slab foundations that went through the earthquakes. So if you add on all the serious damage that could have been missed there, it is no surprise you might start to get some very big numbers.

WILL HOMEOWNERS GO AFTER MBIE?

The guidance developed by the EAG and badged by MBIE to help draw a line for EQC and the insurers was always insufficient to the task, says Craig. That needs to be admitted and the appropriate next steps taken.

He says perhaps Dame Silvia's inquiry will have something to say about it and be a spur for action. Personally he suspects eventually rubble and slab home-owners will have to join together in a litigator-funded class action suit.

Far-fetched? Craig doesn't think so. There are enough motivated people in Christchurch still pushing for justice, he says.

He points to yet another of this year's surprises – the potential $300m lawsuit against Southern Response over deceptive insurance settlements.

A landmark ruling has just allowed that to become New Zealand's first "opt-out" funded class action. Claimants settled by Southern Response are automatically included unless they actively want to withdraw.

Already the precedent has been set, Craig says. Why not go after the MBIE guidance issue too?

So nine years on and the talk is not just of foundation problems emerging. The grounds for legal arguments are being prepared, email trails patiently dissected.

It just doesn't have the feel of a controversy about to disappear any time soon.