Why Is Rainwater Coming In Through the Bottom of My uPVC Door?
For rainwater appearing on the inside threshold, sill or floor at the bottom of a closed uPVC door during wet or wind-driven weather.
What this usually means
Water entering at the bottom of a uPVC door is commonly caused by blocked frame drainage holes, displaced or worn weather seals, poor door alignment or a threshold/sill sealing defect. Everest and Anglian both explain that uPVC frames are designed to collect incidental water and drain it back outside through built-in drainage paths. If those paths block, the frame can fill and spill water indoors even though the door itself is not cracked.
What may be causing this
The frame drainage holes are blocked
Clues: Water collects inside the lower frame channel and does not appear to drain outside.
What to do: Clear only the designed drainage openings and retest with a small amount of clean water.
The weather seals are displaced, flattened or damaged
Clues: The rubber gasket is visibly out of position, split or no longer contacts the door evenly.
What to do: Refit or replace the correct seal rather than packing the gap with silicone.
The door is out of alignment
Clues: The door also rubs, needs force to lock or shows uneven compression against the seals.
What to do: Realign the hinges/door so the seals compress evenly around the frame.
The threshold, sill or installation perimeter is poorly sealed
Clues: Drainage holes work but water still appears beneath or around the threshold rather than from the frame channel.
What to do: Have the sill, threshold ends and installation perimeter inspected and resealed correctly.
How to check what is happening
Water may be unable to escape through the intended drainage route.
The drainage path is obstructed.
Wind-driven rain may be bypassing the weather seal.
Misalignment may be preventing proper seal compression.
Can you fix this yourself?
Cleaning designed drainage holes and reseating a loose rubber gasket are reasonable homeowner checks. Door realignment, threshold sealing and failed installation details are better handled by a window/door fitter.
- Soft brush
- Thin non-damaging cleaning tool
- Mug of clean water
- Dry cloth
- Phone camera
What you can safely try
- 1
Dry the frame and threshold
Start dry so you can see where new water first appears.
- 2
Check the designed drainage holes
Remove obvious debris from the drainage slots without drilling or enlarging the frame.
- 3
Test the drainage route
Use a small amount of clean water and confirm it exits to the outside rather than collecting in the frame.
- 4
Inspect seals and door alignment
Look for damaged gaskets and uneven contact around the closed door.
- 5
Have persistent threshold leakage inspected
If drainage and seals are sound, the sill/threshold or installation perimeter may need professional repair.
Call a window fitter if…
- Water is reaching electrical sockets or wiring.
- The door or frame is visibly distorted.
- The threshold is loose or structurally damaged.
- Water continues entering despite clear drainage paths.
- Repair would require drilling into or dismantling the reinforced frame without the system details.
Get the right window fitter.
We already know this problem maps primarily to a window fitter. Choose the closest type of work, add your postcode and continue in the form.
Sources used for this guide
We prefer primary UK guidance, regulators and manufacturers for technical and safety-sensitive claims.
Last reviewed: 1 September 2026. Home Manual updates review dates only when the substance of a guide is checked or changed.