During these periods, the dew point and the temperature get very close to each other, and every structure -- from trees, street signs and lampposts to buildings -- is exposed to daily cycles of wet and dry, acquiring thick coats of condensation overnight which evaporates in the heat of the day. The cycles aren’t particularly extreme, but that gentleness hides destructive forces nonetheless. And if they aren’t accounted for, those forces can be costly -- to building professionals and homeowners alike.

The homeowner noticed the first few small cracks in his stucco several months after construction. The cracks gradually expanded and grew, and within a year, it was obvious that they were the symptom of a deeper problem.

What that problem was, however, was, like the California coast, shrouded in a fog of mystery. The homeowner called his architect, who was stumped. The lath installer, stucco contractor, waterproofer and window installer all defended their work, insisting they had followed the proper installation protocols. Unable to propose a solution until they could determine what was causing the stucco to crack, they turned to Barry Taherin of California Consultants, a professional deeply familiar with complete wall systems who has the investigative prowess to understand what causes them to fail.
Peeling back the onion

What Barry understood was that with structures as complicated as wall systems, where the final assembly involves multiple, overlapping materials and tradesmen, the integrity of each component is dependent on the others. And where windows and doors are involved, that web of interdependency is amplified. This is what makes determining the root cause of a problem so challenging.
Barry and his team began a methodical investigation, working their way in from the outer finish coat of stucco all the way through to wire, paper, fastening and sheathing. They looked at the materials and methods used and analyzed every aspect of industry standards and manufacturer requirements to determine whether or not they were met. What they found didn’t satisfy anyone.

The homeowner just wanted to know who was responsible for fixing the problem. Unfortunately for him, while none of the tradesmen involved were entirely free of guilt, none were directly to blame for the problem, either.

What Barry found was that the wall in question was built without the grooved paper that provides the drainage capacity this wall would have needed. In a solid wall, where the whole assembly is sealed, with no fenestrations, this might not have been a problem.

But this wall had windows and doors in it. And those windows and doors were not sealed well enough to offset the wall’s poor drainage capacity. Many window installers assume that the wall has been built to drain well and use a low quality sealant - or none at all. The contractors who built the wall, on the other hand, assumed the windows and doors would be sealed up tight.

A few miles further inland, where the climate is more consistently dry, there may never have been a problem at all. But on the coast, faced with cycles of wet and dry, the OSB and plywood substrates turned into sponges, soaking up the condensation at gaps on the perimeters of the windows and doors. As the moisture content increased, the wood swelled, causing cracks to form in the stucco, which allowed more moisture in, which created more swelling. And more cracks.

It was the perfect storm. Unfortunately, it’s a storm that happens all too often. And that is remarkably easy to prevent.

If any one of the factors leading to failure had been addressed in construction, the problem might have been less severe. Using a high quality sealant at the point where window, frame and stucco met would have prevented any moisture from getting into the wall. Better wall drainage would not have prevented water penetration around the fenestrations, but it would have localized the problem to those areas.
As it was, the combination of poor wall drainage, inadequate fenestration sealing and climate moisture was catastrophic. Everything -- the stucco, the windows and doors, the weather barrier, right down to the sheathing substrate -- had to be ripped out and redone. The total cost of the repair was more than $60,000 on a house just a year old. The homeowner paid that bill, and then went after the GC and subcontractor. The subcontractor has gone out of business. The GC and the homeowner are trying to reach an agreement.

And what would it have cost to prevent this $60,000 nightmare for the homeowner, the GC and the sub? A paltry $700.

Just $700 spent on sealant and properly applying it around the fenestrations at the time of construction would have prevented the problem from ever occurring. And that may be the cruelest joke in the whole
sad story, but the only one laughing now is Mother Nature.