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Tips for the house buying process - A Structural Engineers insight

In the dynamic world of real estate, the house-buying process can be as intricate as it is exciting. But what can you do to ensure your investment is structurally sound?

With the real estate market starting to heat up again, and summer just around the corner, our goal with this guide is to help you make better decisions when buying a property. So read on and learn a few tips for house buying and how to bring a structural engineering eye to your property purchase.

The Role of structural engineering in home buying

Structural engineering is more than just a technical field; it's the backbone of your future home's safety and longevity. Especially in New Zealand, where earthquakes can strike at any time, the structural soundness of a home is not just a checkbox but a necessity.

When viewing potential homes, it's crucial to look beyond aesthetics. Key structural elements like foundations, walls, and beams ensure the stability of the building, and any damage to them could be an expensive cost to you in the future.

Understanding different structural elements and what to look out for

When considering the purchase of a house, it's essential to have a basic understanding of various structural elements. This knowledge not only helps in identifying potential issues but also aids in making informed decisions. Let us explain the key elements you should check when assessing a prospective home.

The Foundations The foundation is arguably the most critical structural component of any building. It's essential to thoroughly check the foundation when considering a house purchase because it supports the entire weight of the building and ensures structural stability. A compromised foundation can lead to a host of problems, including uneven floors, cracked walls, and in severe cases, structural failure. Identifying issues early can save significant costs and safeguard against potential safety hazards.

Expand the following foundation types to learn more about them and what to look out for

Concrete Slab Foundations

A single, solid concrete slab that forms the base of the house. It's effective in stable soil conditions. What to Look Out For: Look for cracks, especially large or widening ones, which could indicate movement or soil issues.

Pile Foundations

RibRaft Foundations

Retaining Walls Retaining walls play a vital role in managing soil and water drainage, especially in properties with sloped terrains or those located in areas with significant rainfall. They are essential for preventing soil erosion, maintaining landscape integrity, and protecting the structural foundation of a house. A failing retaining wall can lead to soil slippage or flooding, which can undermine the stability of nearby structures, including the house itself.

Expand the following retaining wall types to learn more about them and what to look out for:

Gravity Walls

Rely on their weight (often made of stone, concrete, or timber) to hold back soil.

What to Look Out For: Watch for leaning, bulging, or cracks, which could indicate that the wall is failing.

Cantilevered Walls

Timber Pole Walls

Other Key Structural Components:
  1. Roof Structure: Comprised of trusses or rafters, it supports the roof coverings and withstands environmental loads.

  2. Ceilings:  can indicate the health of the structure above, such as the attic or upper floors. Look for cracks, water stains, or bowing, which could signal roof leaks or structural movement.

  3. Beams and Columns: Beams (horizontal) and columns (vertical) work together to support the structure’s weight.

  4. Floor systems: include joists, beams, and the floor surface itself, and they must be strong and stable. Look out for uneven or sloping floors, and excessive creaking, which may point to weakened joists or foundational issues.

Key terms, Ultimate limit state (ULS), and Servicability limit state (SLS) are also useful to understand and know about. You can read more about these two terms in a previous blog post of ours:

Understanding Seismic implications

In regions like Wellington, where seismic activity is a significant concern, understanding the impact of earthquakes on residential structures is crucial for any potential homeowner. If you are looking at purchasing a larger building, or an apartment in a large building, it’s worth checking the Earthquake Prone Building (EPB) register, to see whether the building is on it:

Seismic hazard in New Zealand

Even if the building is not on the EPB register, some are higher risk than others. When looking at purchasing a house, apartment, or building, its worthwhile considering:

Building Age and Code Compliance:

Older buildings, particularly those constructed before the 1970s, are generally at higher risk. This is because they were built before modern seismic standards and building codes were implemented. These buildings might not have been designed to withstand the seismic forces that newer buildings are.

Building Materials:

  • Unreinforced Masonry (URM): Buildings made with unreinforced brick, block, or stone are particularly vulnerable during earthquakes. They lack the necessary reinforcement to hold the structure together under seismic stress.

  • Hollow Concrete Blocks: Similar to URM, structures with hollow concrete blocks without adequate reinforcement can be weak against seismic forces.

  • Timber: While timber structures generally perform well in earthquakes due to their flexibility, older timber buildings, especially those not properly maintained, can be at risk due to potential rot or degradation.

Construction Methods:

  • Foundation Type: Buildings with weak or shallow foundations are at higher risk, especially on soft or unstable ground.

  • Irregular Shapes: Buildings with irregular shapes or asymmetrical designs are more prone to damage because they can experience torsional (twisting) movements during an earthquake.

  • Soft-Story Buildings: Structures with a "soft" or weak first story (like those with large open areas for windows or garages) are more susceptible to collapse.

Non-Structural Elements: Risk comes not only from the building structure itself but also from non-structural elements like chimneys, parapets, and interior elements (like ceilings and partition walls) which can be hazardous during an earthquake.

Especially common are brick chimneys, which can create a significant hazard in the event of an earthquake. After the Kaikoura Earthquake in 2016, we assessed dozens of brick chimneys in the Wellington region that had been damaged or crumbled due to the shaking.

Engineer assesses a brick chimney

The assessment process (from a structural perspective)

With so much to think about, it can be overwhelming trying to navigate the house-buying process. We have had years of experience helping you understand what structural elements might need further investigation.

To get an idea of what might be required, the steps below are general guidelines on what to do to make sure you are getting the best bang for your buck when assessing the structural integrity of a building.

Step one: Assess the property yourself

While this doesn't replace a professional inspection or structural assessment, when you get a first look at the property, you yourself can identify if there are issues that might be an expensive future fix. Use the information in the structural elements section above to assess whether there might be issues easily apparent.

Step two: Engage a building inspector

Getting a building inspector is highly recommended in general but is a prerequisite for us to carry out a structural assessment. A building inspector can not only give a good overview of the property, but they can also highlight areas that may need us (structural engineers) to assess.

Step three: Engage a structural engineer Once a building inspector has highlighted areas of concern, a structural engineer's assessment becomes pivotal. We can come to the site and write a structural report for you, highlighting any issues, and providing recommendations for repairs or further investigations. Empowering you with the knowledge you need to make informed decisions.

Making informed decisions and beyond the purchase

With our detailed reports and explanations, you're armed with knowledge. This isn't just about negotiating power—it's about planning for a future that's as structurally sound as it is bright.

DTCE Structural assessing damaged structure

Whether it's leveraging the information for price discussions or future-proofing through renovations, we're here to guide you. Our relationship with you doesn't end with the purchase. From alterations to renovations, we're here to ensure that your home evolves with your dreams.

 At DTCE Structural Engineers, we're committed to ensuring that your dream home stands on a foundation of structural excellence. Let us guide you through this journey, ensuring that every step is as informed as it is exciting. For personalized guidance, or to schedule a structural assessment, connect with us.

We're here to simplify, clarify, and illuminate your path to the perfect home.


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