
Leaking Window Repair in Dunedin
Window and Glass Repair Dunedin traces and repairs leaking windows across the city. Water on the internal sill, a damp patch beneath the window, staining down the lining or mould at the corner of the reveal. We water test from the bottom up until the leak shows itself, then repair the cause.
- Water tested bottom up until the leak shows itself
- Blocked drainage is the cause more often than failed seals
- No blanket sealing over the outside of the window
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In the flat southern suburbs there is a complication worth knowing about. Not every damp patch near a window is a leak. Where the water table sits within a metre of the surface, moisture can be coming up through the floor and simply appearing at the coldest surface in the room. Testing tells you which one you have before anyone spends money.
The four things it usually is
Blocked drainage slots, which back water up over the internal sill. That is the most common by a distance and takes minutes to clear.
Perished glazing wedge, letting water past the glass into the rebate. A failed head flashing above the window, where the water enters higher up and appears at the sill. Or an open corner joint in an aluminium frame, which usually puts water into the wall instead of the room.
Why we water test
Each of those causes produces the same wet sill. The only way to tell them apart is to wet the window in stages, starting at the bottom and working up, masking off the parts you have already ruled out.
It takes longer than looking at it and guessing, and it is the reason our repairs hold. Sealing everything in sight is faster and it is why a lot of leaking windows have already been sealed twice before we get there.
Why blanket sealing makes it worse
An aluminium window is designed to let a small amount of water in and drain it out again. Running silicone around the outside of the frame closes those drainage paths.
The water still gets in. It just cannot get out, so it sits in the frame and the reveal and works on the framing timber behind. Undoing that is a bigger job than the original leak.
The staged water test, step by step
Bottom up, one zone at a time
We start at the sill and wet only that zone, then wait. If nothing appears we mask it off and move up to the glass line, then the head, then the surrounding cladding. Each stage runs long enough for water to travel, because a leak at the head can take several minutes to show at the bottom.
Working downward instead, or wetting everything at once, tells you nothing except that the window leaks, which you already knew.
What we do not do
We do not run a bead of silicone around the outside of a frame to see if it helps. Aluminium windows drain by design, and sealing the outside closes the drainage path so the water that still gets in has nowhere to go.
Undoing that later, once it has been sitting in the frame and the reveal for two winters, is a much bigger job than the original leak.
Leaking Window Repair at a glance
- Diagnosis
- Staged water test from the bottom of the window upwards
- Common causes
- Blocked drainage, perished wedge, head flashing failure, open corners
- Not done
- Sealing over the outside of a frame without finding the cause
- Repairs
- Slots cleared, wedge replaced, joints resealed, flashings referred or repaired
- Report
- What we found and what we did, written down
Leaking Window Repair in Dunedin: common questions
Why is my window leaking only in a southerly?
Wind driven rain arrives at pressure and finds paths that vertical rain never reaches. It usually means a small gap that only matters when water is being pushed at it.
Should I just silicone around the outside?
No. Aluminium windows drain by design and sealing the outside traps water in the frame and the wall. It is the most common cause of a small leak becoming a big repair.
Can you tell where it is coming from without opening the wall?
Nearly always, with a staged water test. Opening linings is a last resort and we would tell you before going there.
Recent Dunedin jobs
Got three quotes for retrofitting the front of the house. Only ones who measured every opening and explained why the south facing rooms needed different glass. Fourteen windows over three days and the difference in the mornings is obvious.
Landlord here. Had four flats assessed before the inspections. Two just needed sashes freed up and stays replaced rather than new joinery, which saved me a fortune. Straight answers and a written report I could hand over.
Slider had been jamming for years and we assumed it needed replacing. Turned out to be rollers and a bent track. Two hours, a fraction of the price we were braced for.
Fogged unit in the lounge, measured on the Tuesday and in by the following Monday. Fair price and they cleaned up after themselves.

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