Why Windows Leak During the Monsoon
Windows usually leak during the monsoon because water is entering through worn seals, blocked drainage tracks, gaps around the frame, poor alignment, or unfinished frame-to-wall joints. The glass itself is rarely the first problem. Start by checking where the water appears, whether the tracks are clear, and whether the seals and perimeter joints are still sound.
The first heavy rain of the season is a relief. Then you notice a small pool on the windowsill, or a damp patch spreading on the wall below it, or a thin trickle after a long downpour. Most people’s first thought is that the glass is bad or the whole window has to go.
Usually it’s neither. A window isn’t just a sheet of glass in a frame. It’s profiles, seals, drainage channels, hardware and the joint where it meets the wall, and all of those have to do their job for the room to stay dry. A fault in any one of them can look like a “Windows Leak During Monsoon”
1. Heavy rain with strong wind
In ordinary rain, water simply runs down the outside of the building. In a storm, wind throws it sideways at the windows and pushes it into every joint and gap it can find. Upper floors and the more exposed sides of a building feel this the most.
So if your window stays dry in normal rain and only leaks in a proper storm, think about how well the whole assembly resists weather: the seals, the way the sashes close and how the window was fitted. The glass is rarely the culprit.
2. Tired gaskets and seals
Gaskets are the flexible strips that close the small gaps between the glass and the frame, and between the opening sash and its frame. Sun, heat, damp and years of opening and closing take their toll. Some harden, some shrink, some crack, and some just stop sitting the way they used to. Tiny gaps open up, and in heavy rain tiny gaps are enough.
What to check: Run your eye (and a finger) along the seals around the opening sections. Look for cracks, loose edges, or pieces that have shifted out of place. If they look worn, get them inspected and replaced where needed.
3. Blocked drainage channels
This is the one people miss most often.
Many aluminium sliding windows are built with a track that is meant to collect some water and send it back outside through small openings, usually called weep holes. They only work if they’re clear. Dust, leaves, grit and leftover construction debris can clog them, and then the water has nowhere to go. It fills the track and eventually spills into the room.
What to check: Look into the accessible tracks for dirt or standing water and clean out whatever you can reach. Please don’t seal the weep holes, and don’t drill extra ones. They’re there on purpose.
4. Gaps between the frame and the wall
Sometimes the window is perfectly fine and the water is getting in around it. If the sealant along the edge of the frame has cracked, pulled away or perished, rain can slip straight through. In other cases the opening may not have had proper flashing or waterproofing in the first place. Flashing is simply a protective layer that steers water away from vulnerable joints and back out.
What to check: Look for cracked sealant, visible gaps, or damp patches around the edges of the frame. If water keeps showing up at that junction, have a qualified person look at it. The fix can be bigger than a fresh bead of sealant.
5. Poor installation or alignment
A well-made window can still leak if it wasn’t fitted properly. A frame that’s slightly out of line, joints that weren’t sealed well, installation details that don’t suit the location, or a drainage path that got blocked during fitting can all let water in. Sliding panels that don’t close fully against their seals leave gaps too.
This is why a window’s performance can’t be judged by its parts alone. Frame, glazing, seals, drainage and the wall around it all have to work together.
If your window is leaking, where do you start?
Don’t jump to replacement. A few simple checks will tell you a lot.
- Notice where the water shows up. Is it pooling in the track, coming in around the frame, or
appearing as a damp patch on the wall next to it?
- Clean the tracks you can reach. Clear loose dirt and debris, taking care not to damage the drainage
openings.
- Look over the seals. Cracks, gaps or any sign of wear are worth noting.
- Make a note of the weather. Does it leak in light rain, only when it’s windy, or after rain that goes on
for hours?
- Get it inspected if it continues. If you can’t tell where the water is coming from, or it keeps coming
in, a proper assessment before any repair work will save you time and money.
One thing to avoid: smearing silicone over every gap you can see. Some of those gaps are drainage outlets, and blocking them can make the leak worse.
And if water is reaching electrical fittings or has made the floor slippery, deal with that first and get help quickly.
Can the right window system help? Yes, but it depends on the whole system and on how it’s installed. A good aluminium system should take the building’s exposure into account and include proper sealing and controlled drainage. Correct installation and a bit of regular maintenance matter just as much.
If you’re an architect, builder or homeowner choosing windows, look past the appearance. Ask how the system handles water. What drainage does it have? Which seals does it use? Are the installation details right for how exposed the building is?
Keeping every single drop off the frame isn’t realistic, and it isn’t really the goal. What matters is that water doesn’t reach the interior, and that any water that does get into the drainage channels can find its way back out.
The Dortec perspective
At Dortec Glastal, a window as part of the building, not an add-on to it. It should look right with the architecture, of course, but it also has to be designed, specified and installed with weather, everyday use and long-term durability in mind.
When a windows leak during monsoon, working out where the water is coming from comes first. A correct diagnosis can save you from replacing windows that were fine, repairs that don’t hold, and the same water damage coming back year after year.
Water coming into your room during the monsoon is a symptom, not a diagnosis. Before you blame the glass or order a new window, find out where the water is actually coming from.
FAQ
Why does my window leak only during heavy rain?
Wind-driven rain pushes water into small gaps that may stay dry in normal rain. Exposed upper floors often show this problem first.
Should I seal all gaps with silicone?
No. Some openings are drainage outlets. Blocking them can trap water and make leakage worse.
Are weep holes important in aluminium windows?
Yes. Weep holes let collected water drain back outside. If they are blocked by dust, paint, sealant, or debris, water can overflow into the room.
Does a leaking window always need replacement?
Not always. Many leaks come from seals, drainage, installation joints, or wall interfaces. Diagnosis should come before replacement.
What should I check before calling a window supplier?
Note where the water appears, clean accessible tracks, inspect visible seals, and record whether leakage happens in light rain, wind-driven rain, or long rain spells.
