Q.: While studying a blueprint I discovered that in one place the architect specified 6 x 6--W1.4 x W1.4 mesh to be used in a 4-inch slab. Yet in another place in the same plan the architect called for 6 x 6--10 x 10 mesh. What is the difference between these two kinds of mesh? The service appears to be about the same.

A.: There is no difference between the two products specified. The architect used two different methods of designating the same welded wire mesh. He should have been consistent, using only the new 6 x 6--W1.4 x W1.4 designation. This is a designation established by the Wire Reinforcement Institute several years ago. It expresses the wire size in terms of hundredths of a square inch of cross-sectional area for the convenience of the designer. "W1.4" represents a cross-sectional area of wire equal to 0.014 square inch. The new system of designation is discussed in the article "New Welded Wire Fabric Numbering System Explained," published in our October 1975 issue, page 454. For more detailed information, see the brochure "How to Specify and Order Welded Wire Fabric," Publication TF 501, Wire Reinforcement Institute, 7900 Westpark Drive, McLean, Virginia 22101.