The Role of Downpipes:

Downpipes play a critical role in directing rainwater from the roof’s gutter system away from your home’s foundation. Given Auckland’s unpredictable weather, from sunny days in Parnell to sudden downpours in Henderson, having the right-sized downpipe is essential to prevent potential water damage.

Popular Downpipe Sizes:
In Auckland, there are standard sizes for downpipes that are commonly used in both residential and commercial buildings:

  • 65mm round: Ideal for smaller homes or sheds where the roof area is limited.
  • 80mm round: A popular choice for many average-sized Auckland homes.
  • 100mm round: Used for larger homes or commercial buildings where there’s a need to handle more substantial water flows, especially in areas like Manukau that might experience heavier rainfall.
  • 65mm x 50mm rectangular: These are typically chosen for their aesthetic appeal while offering efficient water flow.
  • 100mm x 50mm rectangular: Suitable for properties requiring higher water capacity and a blend of functionality with style.

Factors Determining Downpipe Size:
The size of a downpipe isn’t just about aesthetics; it’s primarily about functionality. Factors influencing the choice include:

  • Roof area: Larger roofs catch more rain, necessitating larger or additional downpipes.
  • Rainfall intensity: Areas prone to heavy rainfall might require larger downpipes.
  • Gutter size: Downpipes should be compatible with the gutter size to prevent overflow.
  • Building design: Architectural designs might favour a particular size or style for visual appeal.

Safety Considerations:
It’s imperative to ensure downpipes are securely fastened. Loose downpipes can present a hazard, especially during storms. Furthermore, ensuring that water is directed away from the foundation of the home reduces the risk of structural damage. For those living in hillier regions, like Mount Eden, ensuring proper water flow away from the property is crucial to prevent potential landslides or erosion.

Maintenance and Upkeep:
Regardless of size, regular checks and maintenance are crucial. Over time, downpipes can get clogged with debris, especially during autumn when leaves fall. Cleaning them ensures efficient water flow and reduces the risk of overflow or damage.

Expert Installation:
While understanding standard downpipe sizes is valuable, installation should ideally be handled by professionals. Incorrectly installed downpipes can lead to water damage, aesthetic issues, and even structural dangers. My Roofers Auckland offers expert services, ensuring your roofing and downpipes are not only functional but also add to the visual appeal of your property.

Local Regulations:
Auckland Council provides guidelines and regulations for stormwater systems, which include downpipes. Always ensure installations are compliant with local standards to avoid potential legal complications.

5 Common Mistakes with Downpipe Size Selection in Auckland

1. Underestimating Roof Area:
One of the top mistakes homeowners in Auckland make is not taking into account the entire roof area when choosing downpipes. From the spacious villas in Remuera to the compact homes in Ponsonby, each requires a different approach. A roof with a larger surface area will collect more rainwater, and thus, it’s imperative to have a downpipe size that can handle this volume.

2. Ignoring Local Rainfall Patterns:
Auckland’s diverse climate, with some suburbs experiencing heavier rainfall than others, makes it essential to consider local weather patterns. Installing a downpipe that’s more suited for drier climates in places like Waitakere, known for its wetter conditions, can lead to overflows and potential property damage.

3. Mismatching with Gutter Sizes:
It’s not just about the downpipe. The gutter system and the downpipe need to work in harmony. Selecting a downpipe that’s too small for larger gutters can result in overflows, especially during heavy rains. Conversely, a downpipe too large for a smaller gutter might look out of place and not provide any added functionality.

4. Overlooking Aesthetic Integration:
While functionality is paramount, the visual appeal shouldn’t be ignored. Many homeowners in upscale Auckland suburbs like Epsom might choose a downpipe based purely on aesthetics without considering its efficiency in water drainage. This can lead to practical issues down the line, even if the downpipe complements the architectural design.

5. Neglecting Local Regulations:
Auckland Council has specific regulations regarding stormwater systems. Some homeowners might be unaware of these standards, leading them to install downpipes that aren’t compliant. This oversight can result in potential legal complications and even necessitate costly modifications in the future.

In Summary:

Choosing the correct downpipe size is not just about picking what looks best or seems most robust. It’s a balance of factors, including local climate, roof area, aesthetics, and regulations. Avoiding these common pitfalls and seeking advice from professionals, like My Roofers Auckland, ensures both the functionality and longevity of the chosen system.

Frequently Asked Questions About Downpipe Sizes

Can I replace my existing downpipes with larger ones to handle more rainwater?
Yes, you can. However, it’s essential to ensure that the larger downpipes are compatible with your current gutter system and meet Auckland Council regulations. A larger downpipe can effectively handle more rainwater, but always consult with a professional, like those at My Roofers Auckland, to ensure the change doesn’t introduce new issues when installing downpipes.

How often should I check and maintain my downpipes?
It’s a good practice to inspect your downpipes at least twice a year, especially after autumn when leaves and debris are more likely to cause blockages. In areas like North Shore, where rainfall can be more frequent, more regular checks might be beneficial.

Do downpipe filters or guards really help in maintenance?
Absolutely. Downpipe guards or filters can prevent larger debris like leaves and twigs from entering the downpipe, reducing the chances of blockages. Especially for homes surrounded by trees, like those in Grey Lynn, these guards can be an invaluable addition to reduce maintenance efforts.

Are there specific materials better suited for Auckland’s climate?
While various materials, such as PVC, steel, and copper, are used for downpipes, it’s crucial to consider Auckland’s coastal climate. Materials like marine-grade stainless steel or aluminium might offer better resistance against corrosion from the salty air, especially for homes closer to the coastline like in Mission Bay. Always discuss material choices with a local expert to get the best fit for your location and needs.


  • Auckland Council’s Building and Planning Guidelines: These guidelines often contain recommendations about building materials, including guttering and downpipes, ensuring they are suited to the local environment.
  • The New Zealand Building Code: It provides standards and requirements for all building materials, including roofing and related drainage systems.
  • Roofing Association of New Zealand (RANZ): Publications and guidelines from RANZ can offer insights into best practices in roofing, which includes the selection and installation of downpipes.
  • Institution of Professional Engineers New Zealand (IPENZ): Publications and resources from IPENZ can provide engineering-based insights into the best materials and sizes for different building types and environments.
  • Local Auckland Roofing Suppliers and Contractors: Consultations or resources from local industry experts can offer the most up-to-date and practical insights about the challenges faced daily.