Denver, Colorado (1/22/1999) --- Frank Lawson, Jr. of The Lawson Roofing Company, Inc. selected Johns Manville Roofing Systems for two high-profile projects in San Francisco--the U.S. Mint and City Hall. Both were re-roofing projects. The roof on the Mint had failed and a new roofing system was required while the roof on City Hall needed to be replaced to accommodate seismic work from the 1989 earthquake.
"The Mint had been re-roofed 11 years ago and the roofing system had failed," said Lawson. "They wanted to be sure they were going to purchase a tried-and-true roofing system that would last."
Lawson determined the old roof on the Mint had failed in part because of lack of proper drainage. Therefore, it was extremely important to correct the drainage issue with tapered insulation on this new modified bitumen roofing system.
To correct the problem, Lawson installed two layers of insulation. First was tapered polyiso E'NRG'Y 2™ insulation followed by ¾" Fesco® Board insulation. Next two layers of GlasPly® Premier felt were hot mopped and capped with a DynaKap® cap sheet. DynaFlex® was used on flashings. The 30,000 square foot job carries a 20-year NDL (no dollar limit) guarantee.
The project presented some unique challenges for the architect, Woodford/Sloane, the general contractors, Nibbi Brothers General Contractors and The Lawson Roofing Company. Security was very tight and everyone working on the job had to obtain a security clearance. Also, because of the design of the structure, accessibility to the roof was difficult.
Lawson faced some of the same issues of accessibility and unusual structure when re-roofing the San Francisco City Hall. The roof was part of a $285 million seismic upgrade of the entire building due to the 1989 earthquake. As a result, Lawson had to work around the schedule of the other trades. He also had to work within the schedule guaranteed by the general contractor, Huber, Hunt and Nichols of Phoenix.
For this project, Lawson and the architect, Heller, Manus, Finger+Moy, Komorous-Towey Architects selected a Johns Manville built-up roofing system with a 15-year NDL guarantee. The roofing system consisted of ½" RetroFit® Board insulation covered with four plies of GlasPly Premier felt, with DynaFlex flashings. Gravel was then applied over a flood-coat of asphalt.
Lawson was very pleased with the technical support provided by Casey Paulson, the Johns Manville representative. "The reason we use JM materials is because the company provides quality materials, and service that is as good as the product it sells," Lawson said.
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 $1.65 billion in 1997. 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.
