Leaking Window Repair in Dunedin – Water Tested First, Then Sealed or Reglazed

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.

How Window and Glass Repair Dunedin diagnoses and repairs in Dunedin

Guessing at a cause is how people pay twice. Window and Glass Repair Dunedin finds the fault before quoting the fix, which sometimes means saying the problem is not the window at all.

1. Inspect the opening as one system

   Frame, sashes, hardware, seals and drainage all get checked together, because a fault in any of them presents identically from inside. Looking only at the obvious part is how the wrong repair gets sold.

2. Separate condensation from water ingress

   In a Dunedin winter this is the single most common diagnostic question. Water on the inside face of the glass, pooling on the sill, worse in the morning and worse in bedrooms, is almost always condensation. Water appearing after rain and tracking from the head is not.

3. Water test where ingress is real

   Controlled water on one zone at a time from the bottom up, with somebody watching inside. It takes an hour and it is the only reliable way to find an entry point rather than resealing everything and hoping.

4. Check the drainage before condemning a seal

   Aluminium frames let water in by design and drain it back out through weep holes in the sill. Blocked weeps present exactly like a failed gasket. Clearing them costs almost nothing, so it gets ruled out first.

5. Report the cause in writing

   You get told what failed, why, and whether it will recur. Where the cause is a head flashing, the cladding above or the way the room is ventilated, Window and Glass Repair Dunedin says so rather than quoting glazing work that cannot fix it.

6. Quote repair against replacement

   Where both are genuine options they go on the same quote with the reasoning. Most windows Window and Glass Repair Dunedin is called to do not need replacing, and you should be able to see the gap between the two numbers yourself.

7. Test again before leaving

   Every sash opened, closed, locked and checked for even seal compression. On a leak repair the opening is water tested a second time to confirm the fix.

Why leaking window repair in Dunedin is its own problem

The housing stock and the climate here combine in a way that produces faults you do not see in warmer cities.

Old joinery that has already moved

A house that has stood since the 1890s has settled, and the openings have gone out of square with it. A sash that will not latch is very often a dropped or racked opening rather than a failed lock, and adjusting is far cheaper than replacing.

Student and rental housing gets harder use

A large share of the older stock is tenanted, which means more cycles on the hardware and more forced sashes. MBIE inspected fifty three Dunedin student rentals in May and June 2026, which gives some sense of how much attention this housing is getting.

Frost and damp accelerate everything

Around fifty ground frost days a year, and a lot of the older stock heated intermittently. Repeated wetting and freezing at the bottom rail is what turns a small paint crack into a rotten sill within a few seasons.

South Dunedin ground is a factor

On the flat, the water table sits close to the surface and moisture frequently rises from the ground rather than condensing from the air. Window and Glass Repair Dunedin checks that before quoting glass that would not fix it.

What leaking window repair costs in Dunedin

Repair pricing looks unpredictable from outside because it depends entirely on what is actually wrong. These are the bands we quote within.

Diagnosis and call out

A standard assessment covers inspecting the opening as a system and giving you a written cause. Where water ingress is suspected, a controlled water test takes about an hour and is the only reliable way to find an entry point rather than resealing everything and hoping.

Hardware and seals

The cheapest end of this trade. Stays, rollers, catches, handles and gaskets are consumables and replacing them is a fraction of what people expect. Most windows Window and Glass Repair Dunedin is called to do not need replacing and the repair typically sits well under a tenth of a new unit.

Glass and sealed units

A broken pane runs $250 to $600 in a common size. A failed double glazed unit replaced in the existing frame runs $350 to $800. In both cases the frame and hardware stay, which is why repair usually wins on a sound window.

When replacement is the honest answer

Corrosion through the section, a frame distorted by building movement, or where the reason for the job is thermal performance rather than a fault. At that point a repair is money spent on a window you will replace anyway, and Window and Glass Repair Dunedin says so.

Repair or replace: how to decide in Dunedin

Four questions that settle it, in the order worth asking them.

Is the frame itself sound

Aluminium frames usually outlive everything attached to them, and timber frames are repairable far more often than they are replaced. If the frame is sound, almost everything else is a consumable and repair is the clear answer.

Is the complaint a fault, or is it the climate

Condensation running down the inside of the glass on a frost morning is not a fault. No repair fixes it and no reglaze fixes it. Ventilation, heating and thermal performance do, which is a different job with a different budget.

What is the whole of life number

A cheap repair on a window you will replace in three years costs the money twice. A repair on a window with twenty years left is the best value work in this trade. Window and Glass Repair Dunedin puts both numbers on the same quote so the gap is visible.

Is the house being sold or tenanted

On a rental, compliance and durability change the calculation, because the window has to keep working through harder use. On a house being sold, a documented repair is often enough and a full replacement rarely returns its cost.

Finding the actual leak on a Dunedin window

Water appears a long way from where it gets in. Guessing produces a repair that does not work and a customer who pays twice.

We water test before quoting

Controlled water applied to one zone at a time, starting low and working up, with somebody watching inside. It takes an hour and it is the only reliable way to find an entry point.

Blocked drainage is the most common cause

Aluminium frames are designed to let water in and drain it out through weep holes. Blocked weeps turn the sill into a tray, and that presents exactly like a failed seal.

Failed seals and tape

Hardened gaskets and failed glazing tape let water into the rebate. Common, and worth ruling out drainage first because clearing weeps is far cheaper.

When the leak is not the window in Dunedin

A meaningful share of the leaks we are called to are not coming through the joinery at all.

Head flashing and the cladding above

Water entering above the window runs down behind the cladding and emerges at the head. The window is where you see it and not where it started.

The junction between joinery and building wrap

On a retrofitted or badly installed window the seal between the frame and the wall underlay is the path. That is a building repair rather than a window repair and we will say so.

Condensation mistaken for a leak

Water on the inside of the glass and pooling on the sill in winter is usually condensation. Reglazing does not fix it and the answer is ventilation, heating and thermal performance.

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