Storm season readiness for Metro Vancouver buildings

Storm season is the stretch of the year, roughly fall through early spring, when Metro Vancouver takes most of its rain and wind. For a building it means the envelope gets tested for real: drains have to move serious volume, sealant joints face wind-driven rain, and any weak detail that got away with summer weather starts to leak. Readiness means checking those details before the weather arrives, not after the first ceiling stain.

Before the first fall storms a strata should walk the building with a short list: clear roof drains and scuppers, look at sealant joints and flashing for gaps or lifting, check balcony drains and door thresholds, and photograph the current condition. Anything found broken gets repaired while the weather still allows it. The point of the pre-storm walk is to find the cheap fix in October instead of the expensive one in January.

Storms damage envelopes in three main ways. Volume overwhelms drainage, so water ponds and finds seams. Wind drives rain horizontally into joints, window perimeters, and cladding laps that vertical rain runs past. And duration keeps assemblies wet for days, so water that gets in cannot dry out before the next system arrives. Most storm leaks trace back to a detail that was already marginal: a tired sealant joint, a blocked scupper, or lifted flashing.

An atmospheric river is a long, narrow corridor of concentrated water vapour in the atmosphere. When one makes landfall on the BC coast it delivers intense, prolonged rain, usually with strong wind behind it. These systems bring much of the coast's heaviest rain, and for a building the defining feature is duration: the envelope stays loaded for a day or more at a time instead of shedding a short shower and drying out.

In a BC strata, storm preparation for common property sits with the strata corporation, in practice the council and the property manager. That covers the roof, exterior walls, drains, and building envelope. Residents still play a part: reporting leaks quickly, keeping balcony drains clear of pots and debris, and not sealing over vents or weep holes. The buildings that come through storm season well are the ones where council, manager, and residents each know their piece.

New homes in BC come with mandatory 2-5-10 home warranty insurance, and the building envelope portion, which includes defects that allow unintended water penetration, runs for 5 years. That coverage applies to construction defects, not to wear or deferred maintenance, and it only helps buildings still inside the coverage period. For an older building, the practical protection against storm water is maintenance and inspection, and the strata should speak to its broker about what its own policies cover.

Yes, envelope repairs happen all winter in Metro Vancouver, they just take more planning. Leak investigation and emergency response run year round. Sealant work proceeds on dry days when the substrate and temperatures allow it. Coating and membrane work in winter usually needs hoarding and heat so materials can cure. What changes in storm season is the size of the weather window, which is why non-urgent work is better booked into the drier months.

The details fail first, almost never the open wall. Blocked roof drains and scuppers back water up under membranes. Aged sealant joints at windows and panel joints let wind-driven rain through. Loose or damaged flashing lets water behind the cladding. Balcony door thresholds and sliding tracks overflow. On exposed and oceanfront sites, corroded fasteners and anchors give way under wind load. Every one of those is checkable before the season starts.

Document storm damage the same way every time: date and time of the event, photos of each affected area from the same angles, notes on where water showed up and how much, and moisture readings if a contractor or manager can take them. Keep it all in the strata records with the correspondence. Good records help the council prioritize repairs, help contractors scope the work, and give the strata's insurance broker something concrete to work with.

Vancouver International Airport averages 1,189 mm of precipitation a year based on the 1991 to 2020 climate normals, and the North Shore mountains receive considerably more. Most of that arrives in the fall and winter months, often in concentrated multi-day events rather than spread evenly. That seasonal pattern is why pre-storm preparation in September and October matters more here than in cities where rain arrives gently all year.

A small leak in storm season repeats with every system that comes through, and between systems the assembly never fully dries. Wet framing, insulation, and sheathing stay wet for months, which is how rot and corrosion get established. The same drip that shows up twice a winter in a dry year can run weekly through a wet one. Small leaks found in fall are also far easier to trace and repair than the same leaks after months of saturation.

Allweathercoating handles the envelope side of storm season for strata and commercial buildings across Metro Vancouver: pre-storm inspections, roof drain and scupper clearing by rope access, sealant and caulking replacement, leak investigation and repair, and membrane and coating work scheduled around the weather. Crews are IRATA and SPRAT certified and work under WorkSafeBC Part 11 fall protection rules, which lets us reach storm damage on high-rise elevations without scaffolding the building.