When clients call us about water ingress, the first question is usually… “Where’s the leak coming from?”
It’s a fair question – but often the wrong one.
Water has a habit of travelling. By the time it’s visible inside a building, it may have entered several metres away, following cavities, framing or concealed building elements before finally revealing itself. That’s why finding the source of a leak is rarely as simple as looking at the stain on the ceiling.
After investigating countless building defects over the years, we’ve noticed something else. Most buildings don’t leak because one product has failed.
They leak because the interfaces between different systems haven’t been designed, coordinated or constructed properly. It’s where one material meets another that things tend to go wrong. Here are five common facade interface failures:
1. Window sills and jambs
Windows are one of the most common locations for water ingress – not because windows are inherently flawed, but because they bring together multiple materials, trades and waterproofing elements.
Small issues such as inadequate sill falls, poor drainage paths or incorrectly detailed jambs can allow water to bypass the facade’s intended defence.
These defects often remain hidden for years before becoming visible internally.
2. Flashings that don’t quite finish the job
Flashings are designed to redirect water safely away from the building.
But we’ve seen countless examples where they stop short, aren’t correctly integrated with adjacent systems or simply don’t provide a continuous drainage path.
The flashing itself may be perfectly adequate. It’s how it connects to everything around it that determines whether it performs.
3. Curtain wall transitions
Curtain wall systems rarely exist in isolation. They need to connect with precast panels, masonry, roofs, balconies and other facade elements.
Each transition introduces another opportunity for water to find a way in and these interfaces demand careful coordination – not just between products, but between designers, contractors and installers.
4. Movement joints
Buildings move. Concrete shrinks. Steel expands. Wind causes deflection.
Temperature changes create movement every single day.
If movement joints aren’t correctly detailed – or aren’t maintained over time – the facade is forced to absorb movement it wasn’t designed for.
Eventually, something gives.
5. Relying too heavily on sealants
This is probably the biggest misconception we encounter.
Sealants aren’t waterproofing systems. They’re one component of a much larger weatherproofing strategy. Over time, sealants deteriorate. They crack, lose adhesion and require replacement.
If the long-term performance of a facade depends solely on a bead of sealant remaining perfect forever, it’s probably worth revisiting the detail.
Good facade design should manage water through overlap, drainage, pressure equalisation and flashing – not simply by adding more sealant.
The common thread…
Looking at these issues individually, they all seem different but they usually stem from the same underlying problem.
Not poor products. Not poor intentions. Poor coordination.
Most water ingress issues begin at the point where one system hands over to another. That’s why the best facade outcomes rely on close collaboration between architects, facade consultants, structural engineers, waterproofing specialists and contractors from the earliest stages of design.
Good detailing is invisible
One of the interesting things about facade detailing is that when it’s done well, nobody notices. Buildings simply perform.
It’s only years later, when water starts appearing where it shouldn’t, that these small details suddenly become very important.
That’s why we believe some of the best engineering happens long before construction begins – carefully considering the interfaces that most people will never see.
Because in facade engineering, it’s often the smallest details that make the biggest difference.
