Over the last year, Auckland Council has developed an end-to-end prefabrication consenting process that helps provide applicants with clear guidance when applying to use modular or prefabricated elements in building consents.
IT’S INCREASINGLY COMMON for councils to see prefabricated projects, which may include panellised systems, modular components such as bathroom units interconnected stacked or side by side units or whole finished relocatable buildings.
Councils have found this challenging as the traditional council inspection regime was not designed to accommodate factory assembly line processes and adds more time and costs to the whole process.
Finding a better way for compliance
A better way of dealing with compliance is to have good quality assurance (QA) and quality control (QC) processes in the factory. These could provide enough robust checks and balances to give councils the confidence to reduce inspection numbers down to less-frequent audits.
Audits would confirm the factory was following the QA plan and the QC process was recording evidence of compliance as the modules were assembled.
Specialist team set up
To organise this compliance strategy, Auckland Council established a specialist team focused on assessing factory QA processes and carrying out audits in the factories to ensure processes are being followed.
To help the team embed our new modular policy, specific training was undertaken including the familiarisation of best practice and standards used overseas such as the Canadian Standards Association’s CAN/CSA-A277-01 Procedure for certification of factory-built houses.
More specific detailing needed
We learned quickly that factory manufacturing requires a lot more specific detailing to ensure each module can be produced consistently without gaps in the detailing that would require manual intervention.
We saw factories using traditional building plans where assembly workers inexperienced in New Zealand Building Code matters would make simple but costly assumptions.
As an example, when plans didn’t clearly show dimensions for things such as the positioning of a smoke alarm on a ceiling plan or the distance between drilled penetration holes in a floor joist, these details were guessed on the factory floor. In most case, these errors would result in a council factory audit picking up these non-compliances and requiring rework to rectify.
Unfortunately, this audit process is a lag indicator, meaning that there would have been several instances of this same non-compliance already completed before being raised, creating the need to go back to finished modules and rectify those as well.
To stop this happening, more inspections were carried out, and we ended up back at a traditional council inspection regime where hold points along the production line grew, creating costly delays in assembly.
First step is to discuss proposal
Our first step in the process is to meet with the applicant and discuss their proposal.
A product technical statement is requested for all materials, which must demonstrate how they comply with the Building Code and must be provided with the building consent application. Evidence of testing to a known standard or certification by an accredited independent body are among the ways we sign off the materials. The process necessary for applicants to get the factory QA assessed and approved by Auckland Council before the building consent is issued will also be discussed. If the factory has an existing QA plan in place, we assess this and confirm it is fit for purpose with an audit within the factory.
Pre-consent audit of factory
The pre-consent audit will generally only happen once for a factory and is designed to confirm at a high level that the QA process is being followed and the components consistently match the design.
As the building consent hasn’t been applied for yet, this audit is generally carried out on modules unrelated to the consent. This is considered acceptable if they are similar in design as the audit at this stage is focused on how they follow their QA process rather than Code compliance of the module.
Where the QA is considered unsatisfactory, we would require more regular inspections in the factory. This can be done by us or more likely by a mutually agreed third party engaged by the factory.
MOU between council and applicant
Once the factory QA has been accepted, a memorandum of understanding (MOU) is agreed. This is an agreement between Auckland Council and the applicant regarding the acceptance of the factory audit process, including any costs associated with it.
MOU details factory audit process
The MOU will outline the ongoing audit regime, which will be based on the risk and complexity of the design and the factory QA in place. These audits can vary from certain milestones during the factory build to annual factory audits. As previously mentioned, these can be undertaken by us or a mutually agreed third-party contractor.
All factory audits will require the collection and assessment of the QA documentation to date. Testing and certification of materials is also confirmed at these visits. In addition, further random sampling of high-risk materials or processes may also be called for as the auditor deems necessary.
What about factories outside Auckland?
The MOU also enables factories outside Auckland – but still in New Zealand – to deem their products components. This allows one building consent to be lodged in Auckland that will cover the factory build as well as site assembly. The MOU may also place conditions on the factory such as not building the modules before building consent is approved.
Without the MOU agreement, the modules may still be built in another region under a separate building consent issued by the council in that region. However, it becomes much more complex and costly identifying what are the clear delineations between the two consents.
Process after full building consent lodged
If a full building consent application is lodged with Auckland Council, we assess the design for Building Code compliance using standard building consenting processes. In addition, we check that the demarcation between factory and site build is clearly detailed on the plans.
These interface areas will also need to be clearly detailed and coordinated on the plans particularly where there are multi-units involved, which creates challenging structural, fire and acoustic challenges to these junctions.
At the same time, our specialist QA team confirms the inspection regime for the building, which is issued with the consent as part of the conditions. This will determine what inspection or audits need to take place in the factory and on the site during the build period.
Prior to the modules arriving on site, there is a site meeting to ensure the contractor understands the proposed inspection regime and specialist third-party requirements – if any – relating to the build. It’s not uncommon to combine multiple traditional inspections such as structural framing, cavity, wrap and cladding into one inspection, so communication is essential to ensuring good co-ordination between council and contractor.
Important to document work done
Throughout the construction process, good documentation of the work undertaken is important. This should identify any QA process undertaken or third-party inspection of components and identify products used in the construction process.
The purpose of the documentation is to show a clear picture of the compliance of the building work to the consented plans and specifications, which will help establish the work has been completed in accordance with the New Zealand Building Code.
Articles are correct at the time of publication but may have since become outdated.