My Building Has a Low %NBS Rating. What Options Are Available for Buildings with a Low %NBS Rating?

A lower rating does not mean a building has reached the end of its story. From further investigation and targeted strengthening to staged upgrades and redevelopment, owners often have more options than they realise.

A low %NBS rating does not mean a building has reached the end of its story. Owners often have a range of practical options to consider before deciding what comes next.

A Practical Guide for Building Owners, Landlords and Investors

What Low %NBS Building Options Are Available?

Building owners often assume a low rating leads to a single outcome. In reality, understanding the available low %NBS building options can help owners identify practical pathways that align with risk, building performance and long-term investment objectives. Owners should evaluate all available low %NBS building options before deciding on strengthening, redevelopment or other building improvements.

A lower %NBS rating can create uncertainty for building owners.

Questions often include:

• Do I need to strengthen the building?

• How much will it cost?

• Can I still lease it?

• Should I sell it?

• Is redevelopment a better option?

The reality is that a lower %NBS rating does not automatically define the solution.

Before making significant decisions, it is worth understanding the building, the vulnerabilities identified, and the options available.

A lower %NBS rating is the start of a conversation, not the final answer.

What Does a Lower Rating Actually Mean?

A lower %NBS rating indicates that a seismic assessment has identified vulnerabilities relevant to the building's assessed seismic performance.

However, the rating alone does not tell you:

• Which vulnerabilities are most important

• How difficult they may be to address

• The likely cost of any work

• Whether strengthening is required

• Whether the building is a good or bad investment

Those answers require a broader understanding of the building and the information available.

Option 1: Understand the Existing Assessment

Before making any major decisions, understand:

• What type of assessment was completed

• What assumptions were made

• Which vulnerabilities govern the result

• Whether the building has been altered since the assessment

• Whether previous strengthening work has been verified

Many owners focus on the final percentage without understanding the information behind it.

Understanding the assessment is often more valuable than remembering the rating.

Option 2: Obtain Better Information

Where uncertainty exists, a more detailed review may help clarify:

• Structural vulnerabilities

• Areas of reserve capacity

• Future risks

• Strengthening opportunities

• Investment implications

In some situations, better information can significantly improve understanding of a building, even where the headline rating does not change.

A Detailed Seismic Assessment (DSA) may provide a more complete picture of how the building behaves and which structural systems actually govern its performance.

Better decisions are usually based on better information.

Option 3: Consider Targeted Strengthening

Not every building requires extensive strengthening works.

Depending on the vulnerabilities identified, options may include:

• Parapet restraint

• Connection upgrades

• Diaphragm improvements

• Localised wall strengthening

• Targeted life-safety improvements

Different vulnerabilities require different solutions.

The most appropriate response depends on the building, the owner's objectives and the information available.

A lower rating does not automatically mean a large strengthening project.

Option 4: Stage the Work

For some owners, a staged approach may be more practical than completing all work immediately.

Potential benefits include:

• Better budgeting

• Coordination with future refurbishment

• Reduced disruption

• Long-term planning

• Improved capital expenditure management

Staged improvements can sometimes provide a practical pathway where immediate comprehensive upgrades are not appropriate.

Not all strengthening needs to happen at once.

Existing buildings can remain valuable assets while owners evaluate strengthening, refurbishment, redevelopment and long-term investment options.

Option 5: Integrate Improvements with Refurbishment or Redevelopment

Many owners are already considering:

• Major refurbishment

• Redevelopment

• Change of use

• Site intensification

• Tenant-driven improvements

Where this is the case, structural improvements can often be integrated into broader project planning.

This can improve efficiency and help ensure investment supports long-term property objectives.

Engineering should support broader property decisions, not operate separately from them.

Option 6: Do Nothing (For Now)

Sometimes owners choose not to undertake immediate strengthening work.

That can be a perfectly reasonable decision, provided it is informed.

Owners should understand:

• Existing obligations

• Building vulnerabilities

• Future implications

• Property objectives

• Investment risks

before deciding not to act.

A decision to do nothing should be deliberate, not accidental.

Common Misconception

"A low %NBS rating automatically means an expensive strengthening project."

Not necessarily.

The rating identifies an assessment outcome.

It does not automatically define:

• The required work

• The likely cost

• The most appropriate engineering solution

• The best investment decision

Understanding the vulnerabilities, the available options and the owner's objectives is usually far more important than focusing on the percentage alone.

Existing buildings can remain valuable assets while owners evaluate strengthening, refurbishment, redevelopment and long-term investment options.

What Should Owners Ask?

Before making decisions, consider:

1. What information already exists?

Review:

• Existing assessments

• Structural drawings

• Building consent records

• Strengthening documentation

2. What vulnerabilities are driving the rating?

The rating itself is only the outcome.

The vulnerabilities behind the rating are often more important.

3. What options are available?

Most buildings have more than one possible pathway forward.

4. What are my long-term plans?

Investment decisions should align with intended use, ownership strategy and future goals.

5. What happens if I do nothing?

Understand the implications before making that decision.

Key Takeaways

✅ A lower %NBS rating does not automatically define the solution.

✅ Different buildings with similar ratings can require very different responses.

✅ Better information often leads to better decisions.

✅ There is usually more than one practical pathway available.

✅ Understanding vulnerabilities is often more important than focusing on the percentage.

Need Advice on an Existing Building?

Whether you're reviewing an existing seismic assessment, considering strengthening options, purchasing a property or planning the future of a building, Essen Engineering can help you understand the information available and identify practical next steps.

Discuss Your Building With Us

Building Owner Insights Series

Part 1: Understanding Changes to New Zealand's Earthquake-Prone Building System

Part 2: What Does a %NBS Rating Really Mean?

Part 3: When Is a Seismic Assessment Worthwhile?

Part 4: Five Questions Every Commercial Property Owner Should Ask

Part 5: My Building Has a Low %NBS Rating. What Are My Options?

Coming Soon: 

• How to Work Effectively with a Structural Engineer

• Why Existing Building Investigations Matter

  
  

Legislative and Professional Disclaimer

Last Updated: 6 October 2026

This article provides general information only and should not be relied upon as building-specific engineering, legal, financial, insurance or investment advice. Building owners should obtain professional advice specific to their property before making decisions regarding compliance, strengthening, redevelopment or investment.