Construction Metrication Newsletter

Metric in Construction Volume 4, Issue 2 March-April 1995

The following is based in part on material provided by the Brick Institute of America (BIA).

The most commonly used masonry units are clay brick and concrete block. Both are largely modular products. ASTM E835/E835M, Standard Guide for Modular Construction of Clay and Concrete Masonry Units, sets forth metric dimensions for these products based on the basic building module of 100 mm. Many common brick sizes are within a millimeter or two of metric modular sizes and nearly all can fit within a 100-mm module vertically by using 10 mm joint widths. Thus, metrication poses little difficulty for the brick industry.

This is not the case for concrete block, a product too big to fit within a 100-mm module without changing size. Nominal 8 x 8 x 16-inch concrete masonry units must be resized to 200 x 200 x 400 mm--a 4-mm reduction in height and a 7-mm reduction in length. Consequently, block manufacturers will have to purchase new block molds, maintain dual inventories, and develop ways of distinguishing between similar looking metric and inch-pound masonry units during storage and shipping. To help ameliorate these problems, the General Services Administration's Metric Design Guide (July 1993) permits the use of either metric or inch-pound block in metric projects. Inch-pound block may require more cutting and fitting when used in a building built to metric dimensions but GSA's approach gives the block industry more flexibility in adapting to the change.

The following provides both inch-pound and metric dimensions for common brick sizes.

March-April 1995 Metric in Construction newsletter

* Not a modular unit in either the inch-pound or the metric system.

• BIA supports conversion to metric (SI) units of measure as an inevitable action.
• BIA recognizes that the conversion of the building industry is a gradual process and that there will continue to be a need for both metric and inch-pound units in product and design data until the exclusive use of metric is adopted by the construction industry.
• BIA technical publications will continue to provide information in both metric and inch-pound units, as they have since 1978.
• BIA encourages all brick manufacturers and distributors to provide their product literature and other design data in equivalent metric versions or with dual units.
• BIA will work with brick manufacturers to promote the use and manufacture of modular metric sizes through our technical, marketing, and informational publications.
• BIA will continue to work with the federal government and within the codes and standards organizations to provide masonry codes, standards, and specifications in correct metric units.
• BIA encourages the training of bricklayers in vocational programs in the use of the metric system as it relates to brick masonry, including the use of metric tape measures and metric coursing scales.

After over two years of planning, the Lehigh Portland Cement Company converted to the metric system on January 1, 1995. This effort anticipates the metrication of state and federal highway construction in October 1996. Lehigh announced the decision in a letter to its customers on November 1, 1993. Concurrently, it began to identify all activities, from purchasing to delivery, that would be affected by the conversion process. The company then prepared a schedule for converting each activity, held regional metric training sessions for marketing personnel, instructed office workers in metric usage, and met with suppliers.

In the spring of 1994, Lehigh began sending monthly letters to its customers to help prepare them for the change. Among the topics treated in the letters were:

• Bag weights and sizes (bag sizes would not immediately change).
• The conversion of short tons to metric tons.
• The history of the metric system and the progress of its adoption in the United States.
• How to calculate volumes in metric units.
• How Lehigh made the transition internally (coupled with an offer of customer help).
• Metric basics (base units, prefixes, derived units, symbols, and unit conversions).
• A reminder of how easy it has been to adjust to a variety of "metric" products (soft drinks, film, medical prescriptions, and automobiles).

Lehigh's last customer letter, issued this January, announced the switch to the metric system, reviewed upcoming bills of lading, and re-emphasized that bag sizes would not change until the industry became more familiar with metric measures.

One of the largest worldwide producers of cement products, Lehigh sees itself as a leader in the cement industry and predicts that the other major U.S. cement suppliers will convert to the metric system within a year or so.

The AASHTO (American Association of State Highway and Transportation Officials) Metrication Clearinghouse is up and running. Created to "facilitate highway metrication by gathering, organizing, and sharing information in a timely, efficient and cost-effective manner," the Clearinghouse collects and catalogs AASHTO and FHWA (Federal Highway Administration) metric standards, state conversion plans, and related publications and reference materials. It also provides information on the status of software conversion, state and industry metrication efforts, and ongoing metrication issues.

Clearinghouse information is communicated through AASHTO's computer network, the AASHTO VAN (Value-Added Network). For further information, contact Lenora Grier, Clearinghouse Coordinator, by phoning 409-845-5770, faxing 409-845-9848, or sending a message via the Internet at lenora@ttiadmin.tamu.edu.