Brian Hubbs took an all-glass pool near the top of Vancouver’s Butterfly tower, a barrel-vaulted cube over a heritage church, and its three near-impossible jobs: keep the rain out of a low-slope skylight, keep the pool from leaking into the offices below, and use CFD to stop humid air condensing and ‘raining’ down the glass.
A pool, he noted, is one of the riskiest things an enclosure consultant builds. This one sits near the top of The Butterfly, an iconic downtown Vancouver tower raised over a heritage church, the developer bought the airspace above it, enlarging the tower and funding the church’s reconstruction, with the pool carried on slim, arch-like precast that echoes the church below.
A glass pool cube, Hubbs noted, is the worst case: what a pool really wants is no windows and lots of well-insulated wall, and this is all fenestration and no wall. That leaves three jobs, keep water out, keep water in, and keep water off the inside.
Keeping water out is the ‘no-brainer’ that is hardest here: a low-slope skylight in a city where it rains all winter, where such skylights tend to leak. RDH used a Reiko system, but had it rebuilt entirely in silicone, every gasket and every rafter and purlin drainage channel welded into one continuous silicone gutter, so nothing buried in the assembly ages faster than the rest and needs digging out mid-life. A harsh flood test, run deliberately without the outer weather seal, found the one leak: a toggle screwed through an EPDM gasket that did not self-seal, exactly the kind of thing only a test catches.
Keeping water in matters because the pool sits over occupied office space, a leak does not just annoy the tenants below, it can, over years, damage the structure (he pointed to Florida’s pool-related collapses). And keeping water off the inside is the natatorium problem: in a cold climate, humid pool air condenses on cold glass and ‘rains’ back down, wrecking finishes and durability.
The answer to that last one was computational. RDH built CFD modelling into the enclosure design, using it to place the HVAC so that warm, dry air washes the glass and condensation never forms, reconciling an iconic all-glass form with the physics that usually forbids it. The lesson: point-supported glazing, precast structure and concealed HVAC can coexist in a high-performance pool, but only if the design paradigm shifts to meet the precedent rather than the other way round.