05/13/2009

Roofing History

By Richard L. Fricklas

 

It’s been 50 years since James McCawley published the second edition of Roofing – Estimating-Applying-Repairing (Shelter Publications, 1959). This was a major work, solidifying our understanding of roofing systems, and it contained chapters on membrane roofing, steep roofing, and metal roofing.

In terms of shaping the roofing industry and giving insight as to where we are today, McCawley may not be a household name. But, in his time, he made important contributions to the roofing industry, including this text.

Members of the Midwest Roofing Contractors Association (MRCA) are aware of the fact that the McCawley Award (the MRCA’s highest award) is given annually in honor of McCawley to someone in the roofing industry who has made significant contributions to our industry. But, many may not be aware of what his contributions were.

During 1939, McCawley took over as executive director at the National Roofing Contractors Association (NRCA). At the time, the NRCA had just 10 donor members (who put up $1,000 each) to keep the NRCA going. During his tenure, McCawley produced National Roofer, which he later purchased from the NRCA and renamed American Roofer and Building Improvement Contractor.

As McCauley describes in the foreword to his 1959 text, this was to be “a practical handbook describing the mechanics of shelter and the application of roof coverings of asbestos, asphalt, coal tar, metal, slate, tile, and thatch, prepared for the roofing and sheet metal trades, and as a guide for the architect and builder.”

As background for the text, McCawley explains that, back in 1955 (4 years before he published the second edition of his book), the Building Research Institute (National Academy of Sciences) convened several conferences, inviting representatives of all groups interested in the design, manufacture, and application of built-up roofing products (the dominant low-slope roofing system at the time) to focus on improving roofing performance. Looking back, McCawley’s book was the first step in working toward the Building Research Institute’s recommendations. Some of the important recommendations were:

  • Better training of workmen.
  • The NRCA should correlate the major roof problems and direct a coordinated program of research and investigation.
    • Better flashing design.
    • More accurate methods of locating expansion joints.
    • Revise formulae or charts for more accurate selection of thermal insulation.
  • Manufacturers’ committees develop foolproof materials and methods of installation. “An entirely new roof design based on new materials we do not now have might be the answer.”
    • Improve strength and elasticity of felts.
    • Develop special light-colored self-cleaning aggregate for use on built-up roofs that will protect the roof from hail and sunlight, and reduce the heat-absorbing characteristics of the roof.
    • Develop better fastening devices and methods.
    • Develop insulation with high insulating value that can be placed in plastic form (to eliminate joints) is unaffected by water, is impermeable, and is strong enough to support roof traffic.
  • Determine the suitable job conditions for proper application of materials and advise the applicators.

Let’s review some of the Construction Industry Council’s recommendations and see how well we’ve done in this half-century…

Recommendation No. 1: The U.S. Department of Labor should initiate an intensive program designed to train all roofing workmen, especially the newer men, to know when and how to best handle and apply roofing materials.

Unfortunately, this never happened, although grants from OSHA have been made to improve fall protection and deliver safety training in Spanish.

In Canada, especially through the Roofing Contractors Association of British Columbia (RCABC), a training center is available for training roofing workers.

In the United States, for built-up roofing, training was left to the contractors while the materials suppliers provided occasional inspection before bonds were issued. Roofing unions provided well-organized worker training, mostly in larger cities, such as Chicago, San Francisco, Philadelphia, and Kansas City. There continues to be a union presence estimated at 20 percent of the current workforce.

The Roofing Industry Educational Institute was created in 1979 to provide unbiased technological information on roofing systems. Economic conditions resulted in its demise and merger with the NRCA in 2000.

Meanwhile, suppliers of newer roofing systems, such as single-ply, modified bitumen, sprayed-in-place polyurethane foam, and metal systems, recognized that intensive education was necessary for these systems to succeed. Individual manufacturers provided this education, generally at central training centers. Technical field support was provided at start-ups of projects, along with more stringent inspections than for BUR systems.

Recommendation No. 2: The NRCA should accept responsibility for correlating major roof problems and directing a coordinated program of research and investigation.

The NRCA deserves major recognition in this regard. It has funded research in a number of technical areas, including cellular plastic foams (phenolic foams, delamination, or crushing of polyurethane foam, aged conductance of foams, etc.).

The NRCA’s manuals set a standard for the industry, and most manufacturers have revised their manuals to agree with the NRCA details and specifications. NRCA’s Material Guides provide an index, in a standardized format, of virtually all products available today with referenced specifications, such as ASTM, FM, UL, etc.

NRCA’s Project Pinpoint was a way to highlight problems within generic types of roofing.

Recommendation No. 3 (for Technical Committees): Develop more accurate methods for determining proper location for expansion joints in both structure and roofing.

This is more complex than it first seems. Most roofing manuals recommend that construction joints be provided at not over 150 to 200 feet. Perhaps the recommendation that “joints shall be provided wherever the roof is likely to split” is a tongue-in-cheek guideline with a modicum of accuracy. While elastomeric roof membranes can be elongated by several hundred percent, new concerns, such as for membrane shrinkage and wind loads, still recommend anchorage at perimeters and roof penetrations.


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Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.

Add highly responsive multi-zone comfort to any building project, in any climate. Our CITY MULTI H2i R2- and Y-Series VRF systems give you flexibility to fit the needs of any building. Enjoy 100% heating capacity at 0°F outdoor ambient, and 85% heating capacity at -13°F outdoor ambient.  For more information, log on to www.mitsubishipro.com

 
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