When Water Infiltration in Glazing is a GOOD thing

Before you think I've gone completely crazy, let me explain. If you consider that a glazed structure, be it a simple rooflight or thousands of square metres of glass and aluminium is a "live" organism. By that I mean that it is constantly subjected to wind, rain, thermal movement and forces from the surrounding structure.

The result of this constant assault on the glazing is that water will always penetrate through the outer defences, usually gaskets/pressure caps/feature strips etc, by way of capillary action and or gaps created by dynamic wind pressure.

To deal with this, most architectural glazing systems are not designed to be totally waterproof. Rather, most systems are designed to control water infiltration under these extreme conditions and divert that water back to the exterior in some way.

In the case of curtainwall systems the strategy is to guide any moisture that penetrates the horizontal glazing rebate back out through strategically placed weep-holes in the horizontal transomes.

Because most curtainwall systems are used on taller elevations with higher wind loads, the amount of water entering the vertical supports is typically greater than single height glazing and so water is usually channelled from the vertical mullion to the transom at each horizontal connection.

Roof glazing presents it's own additional problems with today's architectural creations spawning complicated joints and intersections. However the basic methodology is the same in that some water is expected through the primary defence and must be expelled through strategically placed weep-holes.

As a result of our inspections we find that all too often, field failures of architectural glazed structures are directly due to improperly installed zone dams or incorrect placement or missing weep holes, resulting in blockages and the resulting leaks damage to client property.