Curtain Wall vs Window Wall: What Vancouver Tower Owners Should Know

From the sidewalk, two glass towers can look like the same building. Same height, same glazing, same aluminum. Yet one of them may cost its strata considerably more in sealant maintenance over the next two decades, and the reason has nothing to do with the glass. It comes down to how the exterior attaches to the structure behind it.

Vancouver’s residential towers are built with one of two glazing systems: curtain wall or window wall. The difference is invisible from the street and rarely discussed at an annual general meeting, but it shapes where a building leaks, how often its joints need work, and how a restoration project gets scheduled. For a council reading a depreciation report or planning a reserve contribution, knowing which system the building has is a genuinely useful piece of information.

The one structural difference

Curtain wall is a continuous skin. The glass and aluminum assembly hangs on the outside of the building structure and runs past the floor slabs without stopping. The floors sit behind it. The exterior reads as one uninterrupted plane from the base of the glazing to the top of the building, and the connection to the structure happens at anchor points that are hidden behind the assembly.

Window wall is built floor by floor. Each unit sits on one floor slab and stops at the underside of the slab above. The concrete floor edge becomes part of the exterior wall, usually covered with a spandrel panel, a metal closure, or exposed concrete. The building is glazed as a stack of horizontal bands rather than as a single skin.

That is the entire technical distinction. Curtain wall passes the slab; window wall stops at it. Everything that follows in this article is a consequence of that one difference.

Why window wall became common here

Window wall is less expensive to fabricate and install, and it can go up floor by floor as the concrete structure rises, which suits a fast residential build schedule. It also does not require the same structural anchoring detail that a hung curtain wall does. Through the years of heavy condominium construction in Vancouver, Burnaby, and North Vancouver, those advantages made window wall the default on a large share of residential towers.

Curtain wall shows up more often on office buildings and on higher-end residential projects, where the budget supports it and the uninterrupted glass plane is part of the architectural intent. Neither system is inherently better construction. They are different products serving different budgets and different design goals, and both are used across the region.

Where each one lets water in

The systems fail in different places, and knowing which pattern applies to your building makes leak investigation faster.

Window wall’s weak point is the horizontal joint at every floor line. The unit below and the unit above meet at the slab edge, and a sealant joint bridges the gap. That joint sits exactly where the building moves most. Floor slabs deflect under load. Aluminum frames expand and contract with temperature. All of that movement concentrates at the one joint that is supposed to keep water out. Over years of working back and forth, the sealant loses its elasticity, pulls away from one substrate, or splits along its length, and water begins tracking in behind the assembly.

The volume is what makes this significant. A twenty-five storey window wall tower has twenty-five horizontal bands of sealant wrapping the entire building, plus the vertical joints between units. That is a large amount of joint length to maintain, and the failure of any one section is enough to start a leak. This is the same movement-driven mechanism described in the guide on expansion joint failure in precast concrete panels, applied to a glazed assembly.

Curtain wall has fewer horizontal breaks, which reduces the total joint length substantially. Instead it depends on its gaskets, its internal drainage paths, and the integrity of the seals at each unit’s perimeter. A curtain wall is designed to accept some water past the outer face and drain it back out through weeps and internal channels. When those drainage paths get blocked or a gasket hardens and shrinks, water that the system expected to shed instead accumulates and finds a way inward.

Neither system is maintenance-free. They simply present different inspection priorities. On window wall, the slab-line joints are the first thing to check. On curtain wall, the gaskets and the drainage need attention.

The maintenance cost picture

Owners often ask which system is cheaper to own. The honest answer is that the totals land closer together than the individual line items suggest.

Window wall carries a higher recurring sealant cost. There is more joint length, the joints are in a high-movement location, and they need periodic replacement as a matter of routine. A strata with a window wall tower should expect sealant replacement to be a regular, budgeted item rather than an occasional surprise. The work itself is well understood and can be done efficiently, particularly by rope access, because the joints run in continuous horizontal bands that a technician can work along.

Curtain wall generates less routine sealant volume, but its component failures cost more. Replacement glazing units, specialty gaskets, and pressure plate hardware for a proprietary curtain wall system are expensive, and matching an older system can require sourcing or fabricating parts. A curtain wall building may go longer between interventions and then face a larger bill when one is needed.

For a depreciation report, the useful takeaway is that the two systems produce different cash flow shapes. Window wall spreads cost more evenly across the years. Curtain wall tends toward fewer, larger events. Both belong in the reserve plan, and the reasoning behind funding either is covered in the guide on contingency reserve fund versus special levy.

Identifying what your building has

You can usually tell from the outside. Stand back far enough to see several floors at once and look at the floor lines.

If a horizontal band interrupts the glass at each level (a strip of concrete, a metal panel, or an opaque spandrel) and it lines up with the floors all the way up the building, that is the signature of window wall. The band is covering the slab edge, which is part of the exterior in that system.

If the glass and aluminum read as one continuous plane and you cannot pick out the floor levels from the exterior, that suggests curtain wall. Interior clues help too: in a window wall unit, the frame typically sits at the floor and the ceiling, and the slab edge is right at the exterior wall.

The building’s original architectural and structural drawings give a definitive answer, and a building envelope condition assessment will identify the system as a matter of course. If your strata has had an assessment done, the system type is in that report.

Thermal performance and condensation

Both systems put a lot of aluminum into the exterior wall, and aluminum conducts heat readily. Where the framing is not well thermally broken, it becomes the coldest surface in the wall assembly, and in a Vancouver winter that is where interior moisture condenses first.

Window wall adds a second consideration: the concrete slab edge is part of the exterior. A slab that runs from a heated interior out to an exposed edge carries heat outward and brings cold inward, creating a cold band at the floor line. On buildings where that detail was not insulated well, residents on the units above and below can see condensation and, in bad cases, mould at the perimeter. The mechanism and the fixes are set out in the guide on thermal bridging and cold spots.

Distinguishing condensation from an actual leak matters here, because the repair is entirely different. Water at a window perimeter in January might be a failed exterior joint or it might be interior humidity finding the coldest surface in the room, and treating one as the other wastes money.

What this means for restoration planning

The system type shapes how a project runs.

Window wall restoration usually means working continuous horizontal bands at each floor line. That suits an access approach that sweeps the elevation floor by floor, and rope access handles it efficiently because a technician can descend a line and work each joint in sequence. The scope tends to be defined by elevation and floor range rather than by individual units.

Curtain wall work is more often targeted. Specific units, specific gaskets, specific drainage paths that have stopped working. The scope comes out of a survey identifying which components have failed rather than a blanket pass over the whole face. Access still matters, but the work is concentrated rather than continuous.

Either way, the survey comes first. A restoration scope built on an actual condition survey of the right system produces a tender that contractors can price consistently and a project that does not generate a stream of change orders once work begins.

The practical summary

Curtain wall runs past the floor slabs as a continuous skin. Window wall stops at each slab, putting the floor edge in the exterior wall and adding a sealant joint at every level.

Window wall means more joint length in a higher-movement location, so more routine sealant maintenance and more attention to the slab-line detail. Curtain wall means fewer joints but more expensive component replacement and a greater dependence on gaskets and internal drainage staying functional.

Most Vancouver residential condo towers from the heavy construction years use window wall. If that describes your building, budget for sealant work as a recurring item and treat the floor-line joints as the primary inspection target. If your building is curtain wall, the gaskets and the drainage paths deserve the same attention, and the reserve should anticipate larger, less frequent interventions.

Either system will keep water out for decades when it is maintained. Neither will do it on its own.

Sources and further reading

• BC Housing, Building Enclosure Design Guide, Wood Frame Multi-Unit Residential Buildings, referenced 2026
• Canada Mortgage and Housing Corporation, Best Practice Guide: Glass and Metal Curtain Walls, referenced 2026
• BC Building Code, Division B Part 5 (Environmental Separation), referenced 2026
• Allweathercoating field observations on Metro Vancouver residential towers, 2026