Lesson-Never Underestimate The Power of Wind Driven Rain to Penetrate the Building Envelope

Contractor for UC Davis Project to Repair Leaky Facade 

 Sandstone to come down for leak fix at Mondavi Center

August 17, 2011

By Dave Jones

The curtain is going up on a big show outside the Mondavi Center for the Performing Arts.

In this case, the curtain is scaffolding all along the building’s south wall, from the ground to the roof. Workers will be removing all of the sandstone — an estimated 50,000 tiles — to repair the waterproofing underneath.

The project is expected to last into December. During this time, the real show, inside the center, will go on as scheduled.

The scaffolding, scheduled to go up around the end of the month, will be enclosed in mesh to protect the workers from the elements. In addition, the beige-colored mesh will minimize the visual disruption.

After removing the stone, the workers will replace the sheathing and the waterproof membrane, to stop rainwater from getting inside, as has happened periodically since the center’s construction 10 years ago.

Leakage tied to wind speed, rain angle

Alex Achimore, senior project manager with UC Davis’ Design and Construction Management, said the Mondavi Center's water inlfiltration problem usually occurs only when the wind is of sufficient speed to push the rain into the wall at a certain angle.

The university and McCarthy conducted extensive testing of the wall to zero in on the problem and develop the solution. It is not an easy one.

The waterproof membrane goes on as a liquid, like paint, and solidifies on the sheathing that goes over the building’s frame. Therefore, workers must remove the sheathing, and, to get at the sheathing, they must remove the sandstone and the mortar under the stones.

“Unfortunately, the stones are bonded to the sheathing and will not come off in such a way that they could be reused,” Achimore said.

“We are applying new sheathing and new waterproofing, and the stones will be set in place over a half-inch mortar bed that is made by the waterproof membrane manufacturer, so that they are compatible and bond.”