Stucco Waterproofing in Los Angeles, CA

Los Angeles gets most of its annual rain in a handful of storms, often driven sideways by wind off the ocean, and that pattern hides bad detailing for years. A wall can go three dry seasons without complaint and then take on more water in one February week than it can shed. The failures we are called to are almost never surface failures. They are missing kickout flashing at a roof to wall intersection, a window head with no flashing above it, a parapet with an open joint at the cap, or a deck ledger where the waterproofing membrane died at the wall instead of turning up behind the barrier.

The California Building Code has tightened what a stucco assembly has to do with the water that does get in. Section 2510.6 now requires drainage on the exterior side of the water resistive barrier with a minimum drainage efficiency of ninety percent measured under ASTM E2273 or Annex A2 of ASTM E2925, and a space or drainage material of not less than three sixteenths of an inch behind the plaster. That is a shift in philosophy from resisting water to draining it, and it changes which barrier products and which lath details are acceptable on new Los Angeles construction and on substantial reclads.

Multi family buildings carry an additional obligation that puts wall waterproofing on a calendar. Senate Bill 326 requires inspection of exterior elevated elements in condominium buildings, and Senate Bill 721 covers apartment buildings with three or more units, both on recurring cycles. Balconies, walkways, and stairs fail at the same place stucco walls fail, which is the junction between a horizontal waterproofed surface and a vertical clad one. We do the wall side of that work and coordinate with the deck coating contractor so the two systems overlap in the right order instead of butting at a caulk joint.