A fresh take on glazing and drainage methodology

Break out of the fish tank: glazing and window system drainage for real life

In Australia, particularly in Melbourne, commercial architectural window and door systems are often silicone glazed. In many ways, this has led to stagnation of improvements in the manufacturing processes, including innovation in window system drainage.

Dry butted frame joints leak – don’t believe anyone who says differently – and silicon attempts to mask this poor manufacturing. Quite often, silicon glazing is used to stop water entry (to treat a window like a fish tank) and only masks a larger issue that will eventually cause problems.

Very few companies have seriously addressed the issues related to “controlled leakage”. Commercial windows are designed to leak. Vertical members (jambs and mullions) are down-pipes and horizontal members (especially transoms) are gutters. This core principle of drainage through the frame into a subsill is what all commercial framing systems ought to do.

Departure from traditional thinking

Into every life, a little rain will fall. By designing the EDGE commercial aluminium window and door systems with this fact of life in mind, we incorporated a practical, reliable solution to deal with moisture, be it from rain, humidity or condensation.


A major EDGE Architectural innovation is our suites’ rainwater window system drainage methodology, Watershed. Watershed manages and directs the flow of rainwater through the frame system to the external perimeter of the building. The concealed transom drainage system directs water over and around the edge of glass.

Designed to be factory fitted during transom assembly, the Watershed component increases quality control and decreases fabrication costs.

Once properly assembled, Watershed ensures water cannot run from the end of the transom on top of the glass or the glazing wedge. It eliminates ugly external drain holes in the face of sills and transoms. Treating windows as “fish tanks” with silicone glazing doesn’t stop water entry and external drain holes actually become an entry point for water. Good systems design allows water entry and effectively deals with drainage.

Watershed allows the safe passage of water in front of the glass, using vertical members (jamb and mullion) to direct water through the system for collection by the subsill.

Glazing wedges

Traditional “roll in” wedges have been used in our industry since window manufacture began. Usually manufactured from PVC, roll in wedges are commonplace in the residential window industry, but have a poor reputation in the commercial market, as PVC shrinks and a roll in wedge can quite easily roll back out.

The EDGE Architectural ranges do not follow tradition. Our systems use high performance, purpose designed seals, that cannot shrink, are UV stable and cannot fall out once properly fitted. Our framing gaskets are “top loaded” into the frame, unique in Australia, and manufactured from co-extruded Santoprene™ with a rigid backing which gives audible feedback when being fitted (we call it “a satisfying click”).

The gaskets can be used on both sides and treated either as a captive or roll-in wedge in one. It fits relatively flat into the pocket and is easily fitted in the factory or on the project site.

  • The wedge gives an audible “click” as the co-extrusions keys into the pocket, ensuring the wedge is properly seated.
  • Santoprene is the best material available for long-term durability and anti-stretch features.
  • The co-extrusion backing gives an easy identifier of thickness and further enhanced anti-stretch capabilities of the wedges.
  • Our top-loaded pocket was designed for fitting the glazing wedges.
  • Easily factory fitted.
  • When glazing, the wedge cannot be dislodged.
  • The inner leg on the pocket is lower than the face of the frame. This gives a perfect detail to run a bead of silicone prior to fitting the inner wedge. With the leg lower than the face of the frame, there is less chance of ooze.
  • Pocket design is clean and uncluttered with no restricting legs inside it.
  • The back of the pocket is 5mm wider than the gap. This make it easier to angle glass into the pocket.
  • Pocket depth is 28mm on deep and 17mm on shallow, allowing for a full 12mm glass bite and edge distance requirement as perAS4555 (insulated glass units) Table E5.1.

Anti-drop out glazing beads

The glazing bead locks into place by locating into a captive groove under pressure from a glazing wedge or foam rod in the pocket. Glazing beads can be used on the underside of transoms, ensuring water is better contained within the glazing pocket. The anti-drop out bead ensures the bead cannot dislodge. No other commercial aluminium window and door system offers this feature.

Internally or externally glazed

For greater flexibility in manufacture, most suites can be internally or externally glazed.

Where air goes, water will follow

Watershed, the EDGE Architectural glazing methodology and window system drainage methodology ensures dry interiors and prevents the build-up of still water, recurring condensation and even mould that can occur in standard framing systems.