Structural Engineers: Auckland + Christchurch

Prendos structural engineers are leaders in the design and strengthening of single and multi-storey buildings – from new builds to extensions, renovations and alterations of existing properties. 

Using knowledge gained from the structural remediation of countless buildings, our professional structural engineers provide robust, pragmatic, economic solutions and expert structural advice – either as a stand-alone service or in conjunction with our in-house design team.

Our work covers residential, commercial, industrial, educational and healthcare properties, and we offer specialist solutions for even the most difficult engineering challenges, from historic or brick buildings to earthquake damaged properties and those requiring seismic strengthening.

We provide Structural Reports for existing buildings or any unconsented building works, and can conduct Structural Peer Reviews – assessing other’s designs for best practice and code compliance.

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Structural Engineering for New Builds

The 2011 Canterbury and 2016 Kaikoura earthquakes have seen structural engineers adopt new and innovative designs to incorporate the latest seismic resisting systems. Our team has pioneered seismic systems that meet the upgraded risk in Canterbury, while progressing the profession throughout the country. 

If you’re designing a new building, we can inform you of the level of seismic resilience required by the NZ Building Code, and help you implement low damage systems that increase this resilience beyond minimum requirements.

Seismic Assessments and Strengthening: 
What You Need to Know

Feeling bewildered by the array of earthquake assessments and reporting? You're not alone.

ISA, DSA and %NBS have become part of everyday vocabulary for those in the property and construction industry, and understanding the seismic capacity of a building is now a crucial consideration for any property owner. A building with a high %NBS is a highly marketable investment, but it’s also important to have an understanding of a low NBS, as it can be useful when planning future improvements.

The 2017 Guidelines for the Seismic Assessment of Existing Buildings have been revised to take into account the latest technical developments – including lessons learnt from the Canterbury Earthquakes. One requirement is that the Guidelines must be used as the basis for seismic assessments to determine whether or not a building is earthquake-prone.

Earthquake-prone buildings are now defined as being less than 34%NBS (34% New Building Standard), which means the assessments cannot rely solely on ‘judgement’. It also means that Initial Seismic Assessment (ISA) reports are no longer lightweight exercises without legal implications.

Initial Seismic Assessments (ISA) and ISA +

To assess a building’s seismic performance, you begin with an ISA. This is where our experienced structural engineer performs a site investigation and provides a qualitative insight on whether the building is potentially earthquake-prone. The ISA report is intended to quickly identify earthquake prone buildings using minimal resources. We recommend an ISA assessment is carried out when undertaking technical due diligence pre purchase. Having comprehensive knowledge of your building puts you in a far more powerful position.

We offer a basic ISA at a very competitive price, as well as an ‘ISA+’ – which goes a step further towards a Detailed Seismic Assessment if required.

Detailed Seismic Assessments (DSA)

A potentially earthquake-prone building (< 34%NBS) may then require a DSA – which will provide more detailed calculations and establish more accurately whether a building is above the 34% threshold. 

Analyses are typically carried out based on available existing drawings and building properties from the Council, as well as measurements taken during site investigations and, if required, concrete scanning to determine the amount of reinforcement in the structure.

The goal of a DSA is to provide a more accurate assessment of the building strength in resisting earthquake. If a building is rated earthquake-prone, a DSA will help ‘pinpoint’ which parts of the building require strengthening. After a DSA is completed, we provide a comprehensive report that typically states the summary of the results, the %NBS of the building and seismic retrofit options if required. We focus on finding the best solution to improve a building’s earthquake resistance while minimising obstruction and cost. 

Seismic Strengthening

If a building does require structural strengthening, the first question is ‘how close to %NBS is an appropriate goal?’. The Guidelines recommend that all buildings below 34% NBS must be strengthened within certain window of time, depending on the hazard the building poses.

Our structural team have had first-hand experience of the devastating impacts of buildings that don’t perform as expected, so we take great responsibility in making sure our work is of the highest possible standard.

• Structural Engineering Designs:
   - New Builds
   - Extensions
   - Renovations
   - Alterations
• Seismic Assessments:
   - Initial Seismic Assessments (ISA)
   - ISA+
   - Detailed Seismic Assessments (DSA)
• Structural Reports
• Unconsented Works Structural Reports
• Structural Peer Reviews
• Construction Reviews
• Feasibility Assessments
• Expert Witness
• Seismic Strengthening Design
• Earthquake/Flood Damage Reports
• Legal & Insurance Services
• ETABS Computer Modelling
• Education Design
• Underwriter Reviews
• Risk Assessment & Management
• Concrete Beam Scanning 
• Building Condition Surveys
• Infrastructure Assessments

Our Work.

Meet with us

If you’d like to talk to us about an existing building, new build project or future property venture, get in touch. We’d love to find out more about your objectives and help you achieve the best possible property solution.

Contact Us.

0800 773 636)


Business Hours.
9am - 5pm

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Prendos New Zealand Limited