Denver, Colorado (4/22/1999) --- Maintaining the historic quality of Frank Lloyd Wright's Hanna House in Palo Alto was the primary challenge facing The Lawson Roofing Company when it re-roofed the project as part of a seismic upgrade of the entire building. Wright originally designed Hanna House as a residence in 1936 for college professors, Jean and Paul Hanna. The house, which is now owned by Stanford University, suffered damage in the October 1989 earthquake.
"In removing and replacing the roofing system, we had to design a system that did not detract from the historical elements of the building," said Frank Lawson, president of The Lawson Roofing Company. "For example, there were no roof drains and we were not permitted to add any. As a result, we had to create slope to drain but not make it so high that it would raise the roof elevation," he said.
Lawson selected a Johns Manville four ply gravel surfaced fiber glass built-up roofing system. Tapered Fesco® Board insulation was covered with a PermaPly® 28 base felt. Three layers of GlasPly™ Premier felt were then applied with a DynaFlex® sheet used on the flashings.
This specification was selected because Stanford University wanted a long-term guarantee with high quality products. The project has a 10-year NDL (no dollar limit) guarantee.
There were a number of challenging aspects to this job. For example, a tree grows through an opening in the roof. Therefore metal flashings had to connect to the tree. The Frank Lloyd Wright designed windows, which were laid into the roof, presented another challenge.
A special flashing system had to be developed to maintain the historical character of the building but also remain watertight. To keep water from the chimney, a custom cricket was fabricated on site with a sheet metal pan and a DynaFlex flashing against the masonry wall.
The architects on the project were Architectural Resources of San Francisco and the general contractor was Rudolph and Sletten.
Johns Manville (NYSE:JM) is a leading manufacturer and marketer of premium quality insulation and building products. The 141-year-old Denver-based company had sales of $1.78 billion in 1998. Johns Manville produces and markets insulation products for buildings and equipment; commercial/industrial roofing systems; and engineered products including high-efficiency filtration media, fibers, fabric and nonwoven mats used as reinforcements in building and industrial applications. Johns Manville employs approximately 9,300 people and operates 54 manufacturing facilities in North America, Europe and China. Additional information can be found at
www.jm.com
