Metrics

METRIC DESIGN GUIDELINES FOR CONCRETE MASONRY CONSTRUCTION

in. (mm)

in. (mm)

in. (mm)

Metric Design Guidelines For Concrete Masonry Construction Table of Contents
Introduction ........................................................................................................................... Modular Design..................................................................................................................... Metric Design Based on 100 mm Modules........................................................................... Metric Design Based on Inch-Pound Building Modules ....................................................... Inch-Pound Units Used in 100 mm Module Design.............................................................. Recommendations................................................................................................................ Training ................................................................................................................................. Sample Panels ...................................................................................................................... Architectural Units................................................................................................................. Attachment A......................................................................................................................... Attachment B......................................................................................................................... 1 1 2 2 2 3 3 3 3 4 5The Construction Metrication Council has participated in the development of this Design Guide and encourages its use where concrete masonry units are used in metric construction projects. Construction Metrication Council, National Institute of Building Sciences 1090 Vermont Avenue NW, Suite 700 Washington, DC 20005-4905 www.nibs.org

Copyright  2000 National Concrete Masonry AssociationNCMA Publication Number TR-172
NATIONAL CONCRETE MASONRY ASSOCIATION

2302 Horse Pen Road Herndon, VA 20171-3499 www.ncma.org Phone (703) 713-1900 Fax (703) 713-191

Introduction
The Federal government has been taking steps to change the system of measurement used in the United States of America from the conventional inch-pound system to the metric system since the early 1970's. The efforts tomake this change surged forward with the passage of P.L. 100-408, the Omnibus Trade and Competitiveness Act of 1988 (the 1988 Trade Bill), and the subsequent issue of Presidential Order 12770. The 1988 Trade Bill named the metric system as the preferred system of measurement for the U. S. and the Executive Order required federal agencies to convert federal procurement to the metric system.However, the government mandate to convert was not absolute. Both government actions limited this mandate with conditions taking into account the serious practical concerns that were certain to arise. Congress set forth that the conversion should not be required in cases where it would be impractical or likely to cause significant inefficiencies or loss of markets to United States firms. The most commoneffect of the conversion effort has been a simple relabeling of products with equivalent metric dimensions without requiring a physical change in product dimensions. This is commonly called soft metric conversion. The practical implications of soft metric conversion are not difficult to manage and do not create inefficiencies or loss of markets to U.S. firms. Hard metric conversion, on the otherhand, means resizing products to new, rational metric sizes and is principally applied to modular products, where dimensional tolerances are critical. In the inchpound system, modular products are based on a module of 4 inches and in the metric system on a module of 100 mm. Typical modular products are concrete masonry units, recessed lighting fixtures, doors, and sheet products such as gypsum...