Trusted by Aussie Roofers
Engineered roof drainage solutions designed to safely manage heavy rainfall and protect box gutter systems from internal flooding.
A built-in overflow weir positioned exactly 25mm below the sole of the box gutter guarantees water safely discharges outside the building during severe storms or downpipe blockages.
Australia’s only independently certified rain heads, engineered to meet all NCC and AS/NZS 3500.3:2021 requirements for high-capacity roof drainage systems.
Optimised profiles handle extreme Sydney rainfall and prevent box gutter surcharge, with design tables confirming exact flow capacity for your catchment area.
Manufactured from premium 0.55BMT steel, stainless steel, or copper for long-term performance in residential, commercial, coastal, and industrial environments.
Dam Buster Rain Heads are high-performance roof drainage components designed to improve the efficiency and safety of box gutter systems during heavy rainfall events. Installed at the discharge point of a box gutter, they transition water into the downpipe under normal conditions while providing a designated, failsafe overflow path if a blockage occurs.
Read moreMany standard rain heads cover the entire face of the box gutter opening. During a severe storm or if the downpipe blocks, water cannot overtop the rain head, forcing it back up the box gutter and flooding the building interior. This is the core failure mode that Dam Buster rain heads are specifically engineered to resolve. Their built-in overflow weir is positioned exactly 25mm below the sole of the box gutter, ensuring that any excess water spills harmlessly over the front of the unit and down the exterior of the building, completely bypassing the internal roof cavity.
The Dam Buster system relies on gravity and precision engineering to manage water safely. Rainwater collects in the box gutter, flows along the gutter gradient, and discharges directly into the rain head. Under normal conditions, water funnels into the downpipe and flows to the stormwater system. If the downpipe blocks with debris, the water level rises inside the rain head until it reaches the front weir, at which point it spills externally without entering the building structure.
Dam Buster Rain Heads are available in a wide range of materials and profiles to suit both hydraulic and aesthetic requirements. Standard options include Zincalume and Colorbond 0.55BMT for residential and commercial use, Colorbond Matt for architectural finishes, Stainless Steel 304 for corrosive inland industrial environments, and Stainless Steel 316 Marine for coastal properties. Copper, Corten, and Galvanised Steel options are available for heritage and specialised architectural applications.
Available styles include the Stretch Series, Flat Back, Mini, Maxi, Wide, Contemporary, Traditional, and Round Front — known in the trade as the "Ned Kelly." Units suit all standard box gutter widths from 200mm up to 600mm, with custom sizing available for unusual parapet penetrations or non-standard structural constraints. The Flat Back models feature fully adjustable Box Gutter Adapters for simple, secure connections to PVC or odd-sized gutters during retrofit and repair projects.
HMR Supplies manufactures the full Dam Buster Rain Head range locally at our Revesby, Sydney facility. This ensures rapid turnaround times, direct technical support for trades, and custom fabrication capability to keep every project on schedule and fully compliant.
Product Type:
Roof Drainage Rain Head
Material
Durable metal construction
Application
Box gutter drainage systems
Overflow Weir Position
25mm below the sole of the box gutter
Gutter Width Range
200mm–600mm (custom sizes available)
Available Styles
Stretch Series, Flat Back, Mini, Maxi, Wide, Contemporary, Traditional, Round Front
Compliance
NCC and AS/NZS 3500.3:2021 certified
Adapter Compatibility
Adjustable Box Gutter Adapters for PVC and odd-sized gutters
Installation Type
External discharge at box gutter outlet point
Suitable For
Residential, Commercial, Industrial, Architectural
Rainwater collects in the box gutter and flows along the gradient toward the rain head
The rain head receives and manages incoming water at the discharge point
Water flows safely into the connected downpipe system under normal conditions
If the downpipe blocks, excess water rises to the 25mm weir and spills externally, fully bypassing the building interior
Rainwater collects in the box gutter and flows along the gradient toward the rain head
The rain head receives and manages incoming water at the discharge point
Water flows safely into the connected downpipe system under normal conditions
If the downpipe blocks, excess water rises to the 25mm weir and spills externally, fully bypassing the building interior
Install the rain head at the designated box gutter outlet point at the end of the gutter run.
Securely connect the rain head to the downpipe system using the appropriate adapter for the pipe type.
Ensure the sole of the box gutter does not protrude into the rain head body, as this restricts flow and creates a non-compliant installation.
Keep overflow openings clear from obstructions at all times to ensure the 25mm weir can function as designed.
Test water flow to confirm correct discharge into the downpipe and unobstructed overflow performance before finalising.
Install the rain head at the designated box gutter outlet point at the end of the gutter run.
Securely connect the rain head to the downpipe system using the appropriate adapter for the pipe type.
Ensure the sole of the box gutter does not protrude into the rain head body, as this restricts flow and creates a non-compliant installation.
Keep overflow openings clear from obstructions at all times to ensure the 25mm weir can function as designed.
Test water flow to confirm correct discharge into the downpipe and unobstructed overflow performance before finalising.
Installing a unit that cannot handle the roof’s catchment volume will cause immediate overflow during standard rainfall, leading to localised erosion and building damage.
Allowing the box gutter to extend too far into the rain head body negates the 25mm weir rule and is an automatic fail on any plumbing audit.
Relying on guesswork instead of the provided hydraulic design tables puts the entire building at risk of internal flooding. Always calculate the required capacity before ordering.
Innovative direction-change devices designed to redirect water flow safely from box gutters to the point of discharge.
Engineered components that allow upstream direction changes in box gutter systems while maintaining efficient drainage flow.
Short answer: Colorbond is Zincalume with paint on it. Everything else follows from that. They are not competing products from rival manufacturers. Colorbond is made by taking Zincalume steel and
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Meets NCC and AS/NZS 3500.3:2021 requirements, reducing risk of failed plumbing inspections
25mm weir design ensures water discharges externally before reaching internal roof levels
Handles large roof catchments and intense rainfall without system failure
Manufactured from corrosion-resistant materials suited to Australian conditions
Range of profiles, sizes, and custom fabrication options to suit residential, commercial, and architectural builds
Consistent sizing, fast turnaround, and direct support for plumbers and builders
Meets NCC and AS/NZS 3500.3:2021 requirements, reducing risk of failed plumbing inspections
25mm weir design ensures water discharges externally before reaching internal roof levels
Handles large roof catchments and intense rainfall without system failure
Manufactured from corrosion-resistant materials suited to Australian conditions
Range of profiles, sizes, and custom fabrication options to suit residential, commercial, and architectural builds
Consistent sizing, fast turnaround, and direct support for plumbers and builders
Sizing depends on the width of your box gutter and the calculated water flow from your roof catchment area. Our Dam Buster rain heads suit box gutters from 200mm up to 600mm. You do not need to perform complex hydraulic calculations — simply reference the Dam Buster Design Tables provided with the product to match your catchment size to the correct rain head profile.
Yes. While standard Zincalume and Colorbond 0.55BMT are our most popular options, we fabricate rain heads in Colorbond Matt, Stainless Steel 304, Stainless Steel 316 Marine for coastal areas, Copper, Corten, and Galvanised Steel for heritage or specialised architectural applications.
Absolutely. The Flat Back versions feature fully adjustable Box Gutter Adapters, allowing simple, secure connections to odd-sized gutters, eaves gutters, and existing PVC downpipe infrastructure during retrofit or repair projects.
Because we manufacture locally at our Revesby facility, we offer rapid turnaround times for trades. Standard profiles in common Colorbond colours are often available for immediate supply, while custom fabrication and specialty materials will have short, clearly communicated lead times to keep your project on schedule.
Our team can help you select the best drainage solution for your project.
For all quote requests or general enquiries, please complete the below form and our team will respond as soon as possible.
