Condensation, damp, and indoor moisture in Vancouver buildings

Condensation is water that forms when moist indoor air touches a surface cold enough to push that air past its saturation point. The moisture comes from cooking, showers, laundry, and the people breathing inside the suite. In a Vancouver winter the coldest surfaces are window glass, metal frames, and poorly insulated wall corners, which is why those spots run wet first while the rest of the room stays dry.

Vancouver winters are long, mild, and wet. Outdoor air stays damp for months, so opening a window buys less drying here than it would in a colder, drier city, and well over a metre of rain in an average year keeps the building fabric itself cool and moist. Add progressively tighter construction, and indoor moisture has fewer escape routes. The condensation season runs roughly from the first cool nights of October through to spring.

Yes, given time. Condensation wets the same materials a leak wets: drywall, framing, insulation, and interior finishes. A cold closet corner that runs damp every winter grows staining and deteriorates the finishes, and condensation forming inside a wall assembly can rot sheathing and studs exactly the way slow water ingress does. The damage arrives slower than a storm leak, which is why it gets ignored longer.

Both sides contribute, and the split matters for who fixes what. Occupant habits set how much moisture enters the air: showers, cooking, drying laundry indoors, ventilation use. The building sets where that moisture lands: cold window frames, uninsulated slab edges, weak exhaust fans, missing make-up air. One damp suite in a dry building points toward use. The same stain repeating across a whole elevation points at the building.

Dew point is the temperature at which the air you have, with the moisture it carries, starts giving that moisture up as liquid water. Air holds less water vapour as it cools. Chill a surface below the dew point of the room air, and water appears on it, exactly like a cold glass sweating in summer. Every condensation problem in a building is some surface sitting below the dew point of the air touching it.

Usually yes, in short controlled bursts. Winter air outside Vancouver suites is cool and, once warmed indoors, relatively dry, so exchanging inside air for outside air lowers the moisture load even on a rainy day. A few minutes of cross-ventilation after showers and cooking does more good than a window cracked all day, which mostly chills the wall around it and creates a new cold surface for moisture to find.

The leaky condo crisis put building envelope failure on every strata agenda in the province. Rot hidden inside wall assemblies caused billions of dollars of damage across hundreds of Lower Mainland buildings, and it pushed BC toward rainscreen construction, mandatory home warranty coverage for the envelope, and depreciation reporting. It also taught the industry that hidden moisture, whether it enters as rain or forms as condensation, destroys wood-frame buildings quietly.

The physical components, yes. A BC depreciation report inventories windows, cladding, roofing, and mechanical systems and projects their renewal, and BC strata corporations of five or more lots must keep the report current on a five-year cycle under the Strata Property Act. What the report will rarely say is that the aging windows on the north elevation are why six suites wipe their sills every morning. Connecting those dots takes an envelope assessment.

A light haze at the bottom edge of the glass on the coldest mornings of the year is common in occupied suites and clears as the day warms. Persistent water that pools on sills, drips off frames, soaks curtains, or shows up as staining on the wall below the window sits outside normal. So does fog trapped between the panes of a double-glazed unit, which signals the sealed unit itself has failed.

When damp reports repeat, spread, or resist the simple fixes. One suite with wet windows that improves after ventilation changes can be managed by council. Reports from multiple suites on the same elevation, staining that returns after repainting, musty odours without a visible source, or any suspicion that moisture is forming inside the walls justify moisture meters, thermal imaging, and exploratory openings run by people who do this for a living.

A structured look at both sides of the problem. Inside: where the moisture shows, which suites, which orientations, what the ventilation is doing, and surface readings across the suspect walls. Outside: the envelope details that create cold spots and the state of windows, sealants, and insulation. The output is a diagnosis that separates use factors from building factors, and a scope for whichever repairs the building side actually needs.

Promptly, and faster the wetter it gets. Materials that dry within a day or two generally recover; materials that stay damp week after week deteriorate and can support mould growth. A wet window sill wiped each morning is a maintenance habit. A wall that stays damp to the touch, staining that spreads, or a musty smell that lingers deserves diagnosis this season, and anyone with health concerns about mould should speak with a qualified health professional.