Stopping leaching on a precast stone facade in Orlando

The Darden headquarters building in Orlando has a facade of architectural glass and precast stone, with solar panels mounted on the structure.

Water behind the precast

The building was leaking. The control joint caulking had holes in it, and across the rest of the facade the caulking had shrunk and degraded. Water was getting behind the precast, and the result showed on the outside: staining on the precast stone and on the window glass below it.

This is the ordinary sequence on a precast facade. The sealant fails quietly for a few years, water moves through the joints, minerals leach out of the concrete, and the stain that appears on the stone is the symptom rather than the problem.

Why cleaning alone would not have worked

Washing the stone would have cleared the marks for a season. With the joints still open and water still moving, the leaching would have resumed and the stain would have come back. The water had to be stopped first, or the cleaning was temporary.

What was used on the stone

Stone Restore CB2 and Stone Restore HD cleaned the precast and lifted the staining. Leach Stop was then applied across the precast to seal it, blocking the mineral leaching and the water penetration that had been causing it. The joints themselves were recaulked as part of the same scope.

What was used on the glass

The windows were restored with Glass ReSurfacer Final Polish, part of the Glass ReSurfacer system, which removes the etching that run-off staining leaves in the glass. Glass Defender followed, to shed water and keep new staining off the surface.

Working around the solar array

The solar panels stayed in place and in service throughout. Nothing used on the facade was allowed to reach them.