Letters

Information about CCA-treated cedar

I read with interest the article "Treated wood and roof assemblies," April issue, page 64. Although the information was accurate and informative regarding different treatment chemicals and fastener issues, details regarding treated cedar shakes were not provided.

Cedar shakes and shingles still are accepted with chromated copper arsenate (CCA) preservative treatment because the potential for environmental concerns is virtually nonexistent. CCA-treated shakes and shingles continue to perform well, and pressure preservative treatment factories offer warranties of up to 50 years for this treatment.

CCA treatments are compatible with galvanized, copper and stainless-steel fasteners. Because CCA-treated shakes and shingles do form a component of treated wood assemblies, I wanted to offer this information to your readership.

Randy Engh
British Columbia Shake and Shingle Association
Mission, British Columbia

Support for product differentiation

I fully support the views expressed by NRCA's Associate Executive Director of Technical Services Mark Graham in his column "Asphalt shingles and compliance," May issue, page 72. The current marketing of asphalt shingles in the United States and Canada has left a majority of consumers bewildered about their performances and made proper selection problematic.

The U.S. Department of Housing and Urban Development acknowledged this confusion in its 1999 Rehabilitation Guide, Volume 3: "The proliferation of different asphalt roofing shingle types and styles has made the selection of these materials difficult. In the recent past, shingles were categorized by weight, such as 235, 240, 280 pounds, etc. The weight was generally related to service life. Currently, shingles are classified by warranty duration, such as 20-, 25-, 30- or 40-year. There is no direct relationship between base mat thickness, shingle weight, performance and warranty. Furthermore, asphalt coatings, the type of fillers, mat thickness and shingle weight vary from one manufacturer to another, making it difficult to estimate relative performance."

In Canada, asphalt shingles should comply with the combined and recently revised standard CSA A123.1-05/A123.505, "Asphalt shingles made from organic felt and surfaced with mineral granules/Asphalt shingles made from glass felt surfaced with mineral granules." The scope (Part 1) clearly states the standards apply to shingles of single or multi-tab design and shingles of single or multilayer configuration. The property requirements of shingles consist of a set of minimum and/or maximum values regardless of the shingle design or configuration. As a result, there is no information within the standard that provides useful information to consumers regarding the relationship between these requirements and level of expected performance.

I am perplexed by the fact that in almost every other roofing material standard we have implemented some sort of rational categorization of products based on physical characteristics such as strength, thickness, weight, etc., but have not been able to do so with asphalt shingles. For example, insulation is classified by its compressive strength, asphalts by softening points and penetration, and modified bitumen membranes by surfacing and thickness. Although not perfect, such categorizations provide some indication to consumers as to how these properties may be related to performance and allow a more informed selection among the alternatives based on intended use and in-service conditions.

Surely asphalt shingle manufacturers could agree to develop and implement a coherent classification system for their products that could be included in the material standards. This is even more important given the vast array of new shingle designs and types available in the marketplace. They owe it to consumers and those contractors engaged in selling and installing their products.

Peter Kalinger
Canadian Roofing Contractors Association
Ottawa, Ontario

Following is Graham's reply to the letter:

Thank you for your comments and taking the time to share your thoughts with Professional Roofing's readers.

A number of years ago, NRCA proposed ASTM International develop such a classification for asphalt shingle products as you suggest in your letter. An ASTM International task group was established and met a number of times but disbanded when it became clear a consensus could not be reached. Because ASTM International is a consensus-based, standards-setting organization, a consensus is necessary for ASTM International to revise its standards or publish new ones.

It was interesting to see the efforts put forth at ASTM International by several asphalt shingle manufacturers to oppose the development of classifications for asphalt shingles. At the same time, several other manufacturers generally were supportive. The manufacturers that opposed such classifications claimed the classifications were inappropriate for ASTM International and differentiation between products is best left to the marketplace. ASTM International's rules and procedures clearly allow differentiation of products in their standards as evidenced with asphalt (Type I, II, III and IV), fiberglass roofing felts (Type IV and VI) and polymer-modified bitumen sheets (types and grades).

As far as letting the marketplace decide, I am perfectly fine with that approach if adequate information is provided by manufacturers to allow designers, roofing contractors and building owners to make educated purchasing decisions. As I indicate in my column, such information currently isn't readily available.