What Is a Rain Screen?
A rain screen is a wall design that creates a gap between the exterior cladding — such as siding, stucco, or masonry — and the underlying moisture barrier. Water that gets past the outer cladding can drain and evaporate within that cavity rather than becoming trapped against the structural wall. It's the modern standard for coastal BC construction specifically because our climate demands it.
Why It Matters So Much in This Region
Between roughly the mid-1980s and early 2000s, BC experienced what's now known as the "leaky condo crisis." A construction boom brought designers and building methods from drier climates to coastal BC, resulting in thousands of multi-family buildings clad with "face-sealed" systems that had no drainage gap. When water inevitably found its way past the outer surface, it had nowhere to go — leading to widespread rot, mould, and structural damage. An estimated 45% of the roughly 160,000 condominium strata units built in BC between 1985 and 2000 experienced building envelope failures, with repair costs across the province estimated in the billions.
What Changed
The City of Vancouver required rain screen construction starting in 1996-97, and the BC Building Code adopted the requirement province-wide for coastal climates in 2006. Buildings constructed after these dates are far more likely to have proper rain screen assemblies from the outset; buildings from the affected era may have been retrofitted, or may still be facing the issue.
What to Check Before Buying a Condo or Townhouse
- The building's construction date relative to the 1996/2006 code changes
- Strata meeting minutes and depreciation reports for any mention of envelope issues, leaks, or rain screen retrofits
- Whether an engineering or building envelope assessment has been done
- Visible signs of exterior repair, mismatched cladding, or recent stucco work
What this means for you
A rain screen retrofit on an affected building can cost tens of thousands of dollars per unit through a special strata levy. If you're purchasing a condo or townhouse built between the mid-1980s and mid-2000s, reviewing the strata documents carefully — or having a professional review them — is just as important as the unit inspection itself.