Answer in one paragraph: a leaky window needs replacement when the failure is in the frame or the wall connection around it, and repair is enough when the failure is in a part: the sealed glass unit, the sealant, the weatherstripping or the drainage. In Metro Vancouver strata buildings, windows from the 1980s and 1990s are reaching the end of their service life, so recurring leaks across several units usually point to a building-wide replacement conversation rather than one-off fixes.
Key takeaways
- Fogging between panes means the sealed glass unit has failed. The glass can often be replaced without replacing the window.
- Water at the sill or below the window usually means the perimeter detailing has failed, and that is a wall problem, not just a window problem.
- Repair is economical when failures are isolated. Replacement wins when frames are warped, corroded, or leaks recur across many units.
- In most BC strata buildings, windows are common property, so assessment and replacement are typically a strata responsibility. Check your bylaws.
- Get the diagnosis before the quote: the most expensive mistake is installing good windows into failed wall openings.
Why do windows leak? The five usual causes
Almost every leaky window in this climate traces back to one of five causes.
1. Failed perimeter sealant. The joint between the window frame and the cladding dries, cracks and pulls away, usually 10 to 15 years in. Water tracks behind the frame and shows up at the sill or on the drywall below.
2. Failed sealed unit (IGU). Fogging, condensation or mineral staining between the two panes of glass means the insulated glass unit has lost its seal. This leaks energy rather than water, but it signals the window system is aging.
3. Blocked or missing drainage. Window frames are designed to collect small amounts of water and drain it out through weep holes. When those are blocked by debris, paint or sealant, water backs up into the wall.
4. Frame failure. Warped vinyl, corroded aluminum, rotted wood. The sash no longer closes against the weatherstripping, and wind-driven rain gets past.
5. Failed window-to-wall detailing. The flashing and membrane around the rough opening were never right, or have reached end of life. This is the most serious cause because water enters the wall assembly itself, where it damages sheathing and framing invisibly. It is also the cause a window salesperson is least likely to find.
Warning signs: how to tell if a leaky window is serious
Watch for these, roughly in order of increasing urgency: condensation between panes, drafts and whistling in wind, water pooling on the sill during storms, staining or bubbling paint on the wall below the window, soft drywall around the opening, and a musty smell near the window wall. The first two are window problems. The last three suggest water is getting into the wall, and in our experience that is the point where a council should stop patching and start investigating. On multi-storey buildings, a leak reported in one suite often shows up two floors down, because water travels inside the assembly before it appears.
When repair is the right call
Repair is usually the economical answer when the problem is isolated and the frame and perimeter are sound. Good candidates: a failed sealed unit in an otherwise solid frame (the glass alone can be replaced), localized sealant failure (cut out and reseal), blocked drainage (clear and service the weeps), and worn weatherstripping or hardware. On a building-wide basis, a sealant renewal program across elevations can buy a decade for windows that are otherwise mid-life. A repair-first approach makes sense for buildings with windows under about 20 years old and no evidence of water in the walls.
When replacement is the right call
Replacement becomes the honest answer when frames are warped, corroded or rotten, when sealed units are failing across many suites rather than one or two, when leaks recur after competent repairs, or when the window system is original to a 1980s or 1990s building and the depreciation report already carries a window line item. At that point, per-suite patching is spending good money on a system that is finished. The economics flip: one mobilization, one consistent product, one warranty, and the chance to fix the perimeter detailing properly at every opening.
Insert vs. full-frame replacement: what is the difference?
Insert replacement fits a new window into the existing frame. It is faster and cheaper, but it keeps the old frame and, critically, the old perimeter detailing. Full-frame replacement removes everything back to the rough opening, so the flashing and membrane connections to the wall are rebuilt new. The rule that protects strata councils: if the perimeter is part of the failure, insert replacement rebuilds the problem behind new glass. That distinction is the single most expensive question to get wrong, and it is answered by assessment, not by a product brochure. Our window replacement service page describes how we make that call.
What does window replacement cost in Metro Vancouver?
As rough planning ranges for 2026, and noting that access, floor height, product line and concealed damage move these numbers significantly: replacing a failed sealed glass unit typically runs a few hundred dollars per unit of glass. Insert replacement commonly lands in the low thousands per opening. Full-frame replacement with proper membrane integration is higher again, and building-wide programs are usually budgeted per suite after a mock-up suite establishes the real scope. Treat any per-window price quoted before someone has opened up or at least inspected a representative opening as a placeholder, not a budget. Concealed rot found at openings is the main source of surprises, which is why our proposals carry pre-agreed unit rates for it rather than burying an allowance.
Who pays: the strata or the owner?
In most BC strata corporations, windows and exterior doors on the building envelope are common property, which makes their repair and replacement a strata responsibility funded through the operating budget, the contingency reserve fund or a special levy. Bylaws can shift some responsibilities, and older bylaw sets sometimes treat things differently, so check your registered bylaws before assuming. Owners are typically responsible for interior condensation management and cosmetic finishes. This is general information rather than legal advice; your property manager or strata lawyer can confirm how your bylaws allocate it.
How an engineer-led assessment works
Before pricing anything, we determine whether the failure is the window unit, the perimeter, or both. That means inspecting representative openings inside and out, checking drainage paths, moisture-testing the wall below suspect windows, and where symptoms justify it, opening up one location to see the sheathing. The result is a scope your council can defend: which windows need what, insert or full-frame, what the wall repairs are likely to be, and how the work phases so owners stay in their homes. If the building already has an envelope consultant, we work to their specification. Fogged glass on a sound frame gets a glass swap, not a renovation. The point of assessment is spending exactly as much as the building needs, in the right place. If the investigation finds the leak is actually coming from above the window, through the wall or a deck transition, that becomes building envelope restoration or a water leak investigation rather than a window project, and it is far better to learn that before buying windows.
Frequently asked questions
Can a leaky window be fixed without replacing it?
Often, yes. If the frame and perimeter are sound, resealing, drainage servicing, new weatherstripping or a new sealed glass unit will solve most isolated leaks at a fraction of replacement cost.
How long do windows last in the Vancouver climate?
Typically 25 to 40 years for the frames depending on material and exposure, while sealed glass units often fail earlier, around 15 to 25 years. Coastal exposure and poor drainage shorten both.
Is condensation between panes an emergency?
No. It means the sealed unit has failed and is costing energy and visibility, but it is not letting water into the wall. Water staining below a window is the symptom that deserves urgency.
Do all the windows in a strata building need replacing at once?
No. Programs are commonly phased by elevation or by worst-first condition, though doing more at once lowers the per-opening cost because mobilization and access are shared.
Will owners have to move out during window replacement?
No. Trades are typically in a suite for about a day per phase, openings are secured the same day they are started, and owners stay home throughout.
If your building has windows on its mind, whether one stubborn leak or a depreciation report line item, send us a photo and a description and we will tell you what we would investigate first. You can also read more about our window replacement process for strata and commercial buildings.