Integrating Roof and Balcony Drainage in High-Density Residential Projects

Efficient Drainage Strategies for Multi-Level Australian Buildings
In high-density residential developments across Australia, effective roof and balcony drainage is essential to ensure long-term building integrity, occupant safety, and compliance with building codes. Whether designing recessed or cantilevered balconies, a functional and code-compliant drainage system must account for primary outlets, overflow provisions, and fire protection through passive fire systems.

Understanding Drainage Requirements
Each residential balcony is required to have:

• One primary outlet, which connects to a vertical downpipe servicing multiple levels
• One overflow outlet, to alert building management in the event of a blockage
• Fire protection, particularly where penetrations intersect fire-rated slabs or soffits

To ensure efficient drainage, the system must allow multiple balconies and the roof itself to drain through a shared vertical pipe, reducing penetrations and simplifying maintenance.

Traditional Balcony Drainage Configuration
A conventional approach places a roof downpipe through or alongside each balcony slab. The soffit conceals a junction where individual balcony drains are connected to this shared vertical stack.

In this setup:

• Allproof’s uPVC Three-Way Connector Junction (104.100.65.88) connects a 65mm VRTW balcony drain into the shared downpipe
• The penetration is sealed using the Allproof Balcony Downpipe Flange (BDF100) to maintain membrane integrity
• A VRTW65 OFLOW overflow outlet is added to provide visual notification of potential blockage
• The Allproof Soffit Cover provides a discreet underside finish
• As balconies typically form part of a fire compartment, passive fire protection (PFP) is mandatory. Penetrations are treated using Allproof Fire Collars or equivalent compliant PFP systems

This system aligns with Australian NCC requirements for multi-residential drainage, fire compartmentation, and waterproofing continuity.

Simplified Installation: The Allproof Allthrough System
To streamline installation and reduce the number of penetrations, Allproof offers the Allthrough Drainage System, an integrated solution that allows both the roof and balcony to drain through a single penetration per floor.

Key benefits of the Allthrough system:

• One penetration per level for the roof and balcony outlet, minimising detailing complexity
• Independently tested by a NATA-accredited laboratory, confirming its hydraulic performance of up to 5L/s without water splash-back
• Avoids cross-title drainage issues by preventing discharge from an upper balcony or roof onto balconies below

The Allproof Allthrough AT100 O outlet incorporates a membrane clamp ring with a stainless or plastic grate, ensuring long-term performance with both PVC and bituminous waterproofing systems. An overflow outlet is installed separately using the same base and a riser to maintain waterproofing membrane integrity.

As with traditional systems, each penetration requires fire collars to meet Australian passive fire protection standards in multi-level developments.

Roof Drainage Options for Australian Projects
Allproof offers a range of roof drainage products, including:

• Sureflow PVC roof drains: Thick-gauge PVC drains compatible with heat-applied membranes
• VRTW roof drains: Available in 65mm and 100mm configurations
• Bronze roof drains: Small and large diameter versions, often preferred for high-load or heritage-style projects
• Stainless steel or plastic grates, with slip-resistant and heelproof options available

All drains are compatible with leading Australian waterproofing systems, including those used for torch-on or sheet membrane applications.

End-to-End Drainage Solutions
From the rooftop to the stormwater connection, Allproof provides a fully integrated drainage system, including:

• Stainless steel downpipes
• Rainwater heads and scuppers
• Balcony and overflow outlets
• Passive fire collars
• Installation hardware and membrane flanges

Manufactured in New Zealand and designed for harsh environmental conditions, Allproof’s drainage systems are specified on major residential and commercial developments throughout Australia and New Zealand.

With over 30 years of collaboration with architects, engineers, waterproofers, and builders, Allproof delivers high-performance drainage solutions backed by independent testing and on-site expertise.

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