Rain coming in around windows or doors? Seal the right joint
Damp around a window or door after heavy rain usually comes from the joint between the frame and the wall, a sill that slopes inwards, or the wall around the opening. Wind pushes rain sideways into any gap, which is why these leaks show up in storms and on the windward side of the building.
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Part of the outside wall leaking in rain guide, which covers every usual source.
Signs you will notice
- Damp patches at the corners or below a window after rain
- Water collecting on the inside sill
- Paint peeling around a door or window frame
- Worse on one side of the building, in wind-driven rain
- Gaps or cracked sealant around the frame outside
Where the water usually comes from
Often more than one source is at work, and each needs its own fix.
Cause 1
Water getting in around the window or door frame
Damp right around the frame, especially at the bottom corners, and gaps or cracked sealant outside.
Check it yourself: From outside, look at the joint where the frame meets the wall and whether the outside sill slopes away from the window.
How it is usually fixed: Remove old sealant, reseal the frame-to-wall joint with a sealant suited to the frame material, and correct the sill so it slopes outward.
Cause 2
Rain getting in through the outside wall
The damp spreads beyond the frame, and the outside wall around the window has cracks.
Check it yourself: Look for cracks running from the window corners on the outside plaster.
How it is usually fixed: Pressure-wash the outside face, fill the cracks with a flexible crack filler, then apply an elastomeric exterior waterproofing system.
Cause 3
Water coming in from a balcony, chajja or ledge
Damp above the window, where a chajja or ledge sits over it.
Check it yourself: Check whether the chajja slopes outward and has a drip groove underneath so water drops off instead of running back.
How it is usually fixed: Correct the slope of the balcony, chajja or ledge so water runs away from the wall, waterproof its top, and add a drip groove underneath.
Methods follow proven, manufacturer-approved waterproofing systems. The right one for your building depends on what is found on site.
What a photo can and cannot tell you
Photo guidance points to the likely source. It is not a confirmed diagnosis.
A clear photo can show
- Gaps and cracked sealant around the frame
- The slope of the sill and the chajja above
- Where the damp shows inside
A photo cannot settle
- The path water takes inside the wall
- Defects in the frame's own internal drainage
Simple checks before you call anyone
- 1Spray water from a hose on the outside of the frame, joint by joint, and watch inside.
- 2Check the drainage holes in sliding window tracks for blockages.
- 3Look at the outside sill slope and the chajja above.
- 4Photograph the frame inside and outside.
When you need someone on site
- The window is on a high floor and needs outside access
- Several windows on the same side are leaking
- The frame itself may need replacing
Where Membrain works on site, a site diagnosis confirms the source, and thermal imaging finds hidden leaks before anything is broken. The app checks whether your pincode is covered.
Common mistakes that waste money
- Filling gaps with cement, which cracks away from the frame.
- Sealing the drainage holes in sliding window tracks.
- Using a sealant not suited to the frame material.
- Sealing only the inside of the frame.
Before you accept a contractor's quote
- Does it remove old sealant before applying new?
- Does it name a sealant suited to aluminium, uPVC or wood frames?
- Are the sill slope and corner cracks included where needed?
- Is a water spray test planned after the work?
Already have quotes? Membrain can compare them on scope, not just price. Planning the work instead? A written specification makes quotes comparable.
How this guide is built
Diagnostic basis
Membrain separates visible signs from possible water-entry mechanisms, then asks for evidence that can distinguish the remaining causes.
Repair-source governance
Public guides stay brand-neutral. When Membrain creates a repair plan, methods and products come from current approved manufacturer documents in its technical library.
Evidence limits
A photo cannot confirm concealed pipes, waterproofing layers or moisture depth. When remote evidence cannot separate the causes, a site inspection is the correct next step.
Technical notes behind this guide
Deeper reasoning on the moisture patterns and water-entry mechanisms used to interpret this problem.
Khidki se paani kyun aata hai?
Baarish mein khidki ke aas-paas seelan aaye toh aksar frame aur deewar ke beech ka joint, andar ki taraf jhuka sill, ya khidki ke corner ka crack zimmedaar hota hai.
Bahar se pipe se paani daal ke ek-ek joint check karo. Sliding khidki ki track ke chhed saaf karo. Cement se gap mat bharo, wo jaldi toot jaata hai.
Frequently asked questions
Why does my window leak only in heavy rain?
Wind pushes rain into small gaps that normal rain does not reach. Windows on the windward side leak first.
Can I just apply silicone around the window?
Only after removing old, failed sealant and cleaning the joint. The sealant has to suit the frame material, and the sill slope must also be right.
Why does water collect in my sliding window track?
Sliding tracks have drainage holes that block with dust. Clean them so water drains outside instead of overflowing inside.
The damp is above the window. Is that the window too?
Often it is the chajja or ledge above. Water runs back along its underside if it lacks a drip groove or slopes towards the wall.
Not sure which one it is?
Share a photo and answer a few questions. Membrain shows the likely sources and a repair plan built from proven waterproofing methods, in minutes. Free to start.
Remote guidance, not a site inspection.