In many respects, the façade just might be the most important component of a new building. It keeps out the weather and pollution, it admits natural light, it holds in comfortable temperatures and well-processed air, it makes a statement to the outside world, and, if you're really fortunate, it becomes an icon. At the same time the sheer complexity of assemblies, fenestration, materials, even colors these days, has grown exponentially in recent years. There are plenty of ways to make mistakes and plenty of rewards for avoiding them. RecentlyHealthcare Buildings Ideas Editor Richard L. Peck and Contributing Editor Shannon Powers-Jones posed questions and got multiple perspectives on the challenges involved from key players in healthcare project delivery.
| Architect T. Brett Roberts Associate Principal and Director of Technical Design, Anshen + Allen Architects, San Francisco, California |
What are some important developments you've seen in use of façade materials?
Rain screen assemblies and double-wall systems are becoming increasingly prevalent in the United States. Water has been an enemy of construction since the pyramids were built, but today's increased concern with healthy buildings that are free of dampness and mold make water-tight façades more important than ever. Even building codes recognize this and are now calling for “drainable exterior assemblies” (IBC Section 1403). But budget is the all-important controller when it comes to choice of materials for the façade, and ultimate decisions always come down to costs.
That said, we're seeing more and more attention being paid to rain screen technology. Rain screens use a variety of materials, but we don't necessarily rely on them for primary weather protection. The technical challenge with rain screen systems however is knitting together the primary wall system to establish an effective weather line-a water/air barrier-that encloses the entire building. It's a challenging process-a lot of detailing is needed here-and that carries cost. But the benefits outweigh those costs: Rain screen systems are either pressure-equalized or pressure-reduced assemblies and, because most building leaks are due to pressure differences between interior and exterior environments, properly detailed rain screens can actually reduce building leaks. Secondly, rain screens offer increased freedom of choice in material palette for the façade. Rain screens can consist of aluminum panels, unitized terra cotta assemblies, cement board, or fiber-reinforced resin panels (some even with natural wood veneers).
