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Engineered directional discharge devices designed to safely redirect water flow from box gutters and sumps to external downpipes without internal pipework.
Pre-engineered geometry channels water horizontally through the building envelope and directly into the external rainhead, preventing back-up during severe weather events.
Engineered to meet National Construction Code (NCC) and AS/NZS 3500.3:2021 requirements, eliminating the risk of audit failures and internal water damage.
Operates with only 50mm to 70mm of clearance below the sole of the box gutter, making these devices viable for the tightest roof cavities where traditional sumps physically cannot fit.
Manufactured from high-grade Australian steel built to withstand the harsh local climate and resist corrosion over decades of service.
Dam Buster side outlets are precision-engineered directional discharge devices designed to redirect water flow at the exact point of discharge in a box gutter system. Rather than dropping water vertically into internal pipework, these units channel water horizontally through the building envelope and safely out to an external rainhead, completely eliminating the need for internal plumbing, bulkheads, and custom sump fabrication.
Traditional box gutter direction changes have always presented significant challenges, typically demanding expensive custom-built sumps, internal bulkheads, and hidden pipework that introduce serious leak risks. Dam Buster side outlets fundamentally change this process. By sitting precisely at the discharge point and using natural gravity to redirect water outward, these devices drastically reduce installation time, structural modifications, and material costs.
Dam Buster side outlets are available in four primary configurations to handle any architectural layout. The ESO (End Side Outlet) features an L-shape to change a single box gutter's direction by 90 degrees, available in left-hand or right-hand models. The TSO (T Side Outlet) allows two intersecting box gutters to discharge into a single external point. The CSO (Corner Side Outlet) is designed specifically for two box gutters meeting at the corner of a building, such as on a hip roof. The XSO (Cruciform Side Outlet) accepts three separate box gutters discharging to one central point, making it ideal for terrace housing party walls.
Units such as the TSO-300 feature on-site adjustability, expanding from 300mm to 450mm wide without additional cutting or special tools. This provides massive flexibility during installation across both standard and non-standard gutter profiles. For projects with highly unusual dimensions, HMR Supplies operates a local Sydney manufacturing facility where custom fabrication ensures a perfect fit without wasting labour hours modifying parts on the roof.
These products excel across a wide range of project types. In new commercial and industrial builds, they allow architects to design cleaner internal ceilings without accommodating large drainage pipes. For residential retrofits in older Sydney properties with failing internal box gutters, side outlets offer a non-invasive solution — plumbers can reroute water externally without demolishing interior walls or ceilings. Whether you are managing terrace house party walls or expansive warehouse roofs, side outlets ensure water reaches the downpipe with maximum efficiency and minimum structural interference.
HMR Supplies manufactures the full Dam Buster side outlet range locally at our Revesby, Sydney facility. This ensures fast turnaround times, direct technical support, and custom fabrication capability for trades across the Sydney metro area and beyond.
Product Type:
Directional Discharge Side Outlet
Material
High-grade corrosion-resistant Australian steel
Application
Box gutter discharge point drainage
Configurations
ESO, TSO, CSO, XSO
Angles Available
Left-Hand (L) and Right-Hand (R) where applicable
Gutter Width Range
300mm–450mm on-site adjustable (custom sizes available)
Clearance Required
50mm–70mm below the sole of the box gutter
Installation Type
External discharge, no internal pipework required
Compliance
NCC and AS/NZS 3500.3:2021 certified
Suitable For
Residential, Commercial, Industrial, Architectural
Water travels along the box gutter or upstream sump toward the discharge point
The side outlet unit receives incoming water at the discharge point
The unit’s geometry channels water horizontally through the building envelope
Water exits safely into the external rainhead and downpipe system, completely bypassing the building interior
Water travels along the box gutter or upstream sump toward the discharge point
The side outlet unit receives incoming water at the discharge point
The unit’s geometry channels water horizontally through the building envelope
Water exits safely into the external rainhead and downpipe system, completely bypassing the building interior
Place the sump at the designated low point of the box gutter run, directly over the primary internal downpipe.
Select the correct model (ESO, TSO, CSO, or XSO) and handedness based on flow direction and gutter layout.
Place the unit at the discharge point, expanding where applicable (e.g., TSO) to securely fit the width of the incoming box gutters.
Seal the unit correctly to the guttering and align strictly with the external rainhead to prevent pooling.
Test water flow to confirm correct horizontal discharge, zero internal leak risk, and compliant performance before finalising.
Confirm a minimum of 50mm to 70mm clearance below the sole of the box gutter before positioning the unit.
Select the correct model (ESO, TSO, CSO, or XSO) and handedness based on flow direction and gutter layout.
Place the unit at the discharge point, expanding where applicable (e.g., TSO) to securely fit the width of the incoming box gutters.
Seal the unit correctly to the guttering and align strictly with the external rainhead to prevent pooling.
Test water flow to confirm correct horizontal discharge, zero internal leak risk, and compliant performance before finalising.
Failing to match the side outlet and accompanying rainhead to the total design flow rate of the roof catchment area is the most frequent compliance failure.
The device must sit level and correctly interface with the external wall penetration. Incorrect positioning causes water pooling inside the unit.
Using non-compatible rainheads or incorrectly sizing the external downpipe will throttle water discharge, causing the box gutter to back up and overflow into the building cavity.
Australian-designed rain heads engineered to safely discharge water from box gutters and perform reliably during extreme rainfall events.
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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Powder coating enhances corrosion resistance, improves durability, and delivers a clean finish.
Use a side outlet when you need to change the direction of water flow at the exact point of discharge and want to avoid running internal pipework through the building. They are especially useful in tight roof cavities where a traditional deep sump physically cannot fit, as side outlets only require 50mm to 70mm of clearance below the box gutter sole. They are also the preferred method when you want to eliminate the risk of internal water damage by forcing all discharge to the exterior of the property.
Sizing is dictated by the total design flow rate of your roof catchment area. You do not need to calculate the side outlet’s capacity directly. Instead, use the Dam Buster design table to select the correct external rainhead for your flow rate. Once the rainhead is correctly sized, the corresponding side outlet automatically possesses the required hydraulic capacity.
Yes. They are exceptionally well-suited for retrofit applications. If an older building suffers from internal box gutter leaks, you can install a side outlet to redirect water to a new external downpipe without replacing the entire roof structure. They must always be paired with a compliant Dam Buster rainhead to ensure the system meets current NCC standards.
Absolutely. While the standard range features high on-site adjustability — expanding to fit gutters between 300mm and 450mm — some architectural projects present unusually wide profiles or specific structural constraints. HMR Supplies operates a local Sydney manufacturing facility where we provide custom steel fabrication for flashings, rainheads, and specialised drainage components to ensure your system fits perfectly and performs flawlessly.
Our team can help you select the best drainage solution for your project.
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