Canterbury Residential Home Foundations
Before the 1930s there were no residential housing building standards in New Zealand. The concrete perimeters were constructed of generally low-grade concrete, with uniformly-graded aggregate, and often used fill such as bricks, bits of old concrete or large stones up to 200-300mm diameter. Over the years building standards were progressively introduced and the approach to residential foundation construction changes.
Post the Canterbury Earthquake Sequence (CES) there are number of guidelines and standards which outline, for example, “different measures for the allowable variation in floor level of newly-constructed foundations”.
Another example of change related to the CES expressly outlawed the use of whole river rounds as subbase material in slab foundations. This was due to testing undertaken by Tonkin and Taylor which found that river rounds were prone to forming unstable bridging arrangements, likely to result in voiding with movement. (Henderson, D. (2013) source)
Due Diligence Foundation Assessment & Reporting
If you believe your home has experienced an earthquake, we believe you need to start from the foundation up. Our due diligence process, which involves a site visit, data gathering and analysis, provided in the form of a Due Diligence Foundation Report, can help you understand if you home has earthquake foundation damage and sets you on the right pathway to reinstate damage in accordance with entitlements.
The Due Diligence Foundation Report is also relevant for property owners wanting robust evidence on the state of their home’s foundation at particular points in time.
Our Reports
Ring and Pile Foundation Due Diligence
Our foundation expert and bot technician will visit your home. An underfloor bot (there is even a low profile bot) is placed under your homes floor and it completes a detailed review of your homes underfloor. We take images of the external face of the foundation, take holistic view of the home, and listen to your concerns.
Back at the office we review the agreed Scope of Work, other agreed data, and complete a detailed analysis of the gathered and complete the image map. Along with our report, a HouseStuff Photo Book is included. Floor levels can also be included and analysed. If we believe there is an insurance issue then we will offer some guidance on the best process to follow. Compared to competitors Housestuff images are cleaner, clearer and crisp.
Our Reports
Ring and Pile Foundation Due Diligence
Our foundation expert and bot technician will visit your home. An underfloor bot (there is even a low profile bot) is placed under your homes floor and it completes a detailed review of your homes underfloor. We take images of the external face of the foundation, take holistic view of the home, and listen to your concerns.
Back at the office we review the agreed Scope of Work, other agreed data, and complete a detailed analysis of the gathered and complete the image map. Along with our report, a HouseStuff Photo Book is included. Floor levels can also be included and analysed. If we believe there is an insurance issue then we will offer some guidance on the best process to follow. Compared to competitors Housestuff images are cleaner, clearer and crisp.
Robotic Subfloor Images
Sometimes all you will need is high quality, clear, crisp and clean images of the subfloor of your ring and pile foundation, with those all important external comparison images.
When that is what you need we manage that with HouseStuff. The robotic technical expert visits your home, places the bot under the floor, takes relevant external images. You are supplied with a HouseStuff Photo Book, inclusive of internal and external foundation images and image map. The original images are included in the package because they are a requirement of quality analysis processes of your homes foundation.
Rubble Ring Foundations
Canterbury residential foundations built before 1974 are distinctive from those found in other regions of New Zealand. Decisions about construction practices were influenced by the availability of cheap and inexhaustible materials; namely the readily accessible ungraded river-rounds (as fill and aggregate); sourced from Canterbury’s braided rivers (and placed quarry or river rock and clay brick as rubble fill).
It has become accepted by EQC that it has under assessed and missed damage to some homes with ring and pile foundations. Indications of an EQC failed repair, or that EQC has missed damage is, for example, visible evidence of a repair, digging a little garden away from a crack repair and finding it carries on below ground garden height, no sub-floor investigation completed by an independent party, no floor levels taken, changes to EQC Scope of Work (identified when reviewing EQC claims files), and more.
Slab Foundations
Many homes with slab foundations did not have detailed foundation assessments completed by EQC, and often no floor levels were taken. For many homes the foundation inspection stopped at the garage slab.
However, since many foundations built prior to the Canterbury Earthquake Sequences (CES) do not have mesh in the slab, many have experienced slab cracking damage, and that damage has been missed. In addition, foundations built prior to the CES in Canterbury used river rounds in the subbase, and earthquakes can cause movement to the subbase according to Tonkin and Taylor.
If you have wall linings that are still showing signs of movement, perhaps unusual humps or hogging in the floor, doors that do not shut correctly, they can all be indications of missed foundation earthquake damage.