METRIC DESIGN GUIDE
Masonry walls have a critical wall thickness for fire resistance and compressive strength.
They also are never relocated after construction. Beyond this, it is not important what
dimension the height and width of a masonry unit is except for appearance, ability to
accommodate metric window and door openings, having even coursing for ties and round
dimensions between openings for ease of builder measurement, and weight of the unit for
lifting. Project requirements then should be limited to these factors, with total competitive
pricing determining the dimensioning. It should be noted that there are a number of
proprietary, nonmortar joint, concrete block systems using English measurements, with
builder labor advantages, that also require a local manufacturer to have different molds for
concrete masonry units, as do metric units.
The "metric modular brick" is the most common. Its size is 90 by 57 by 190mm (3-9/16
by 2-1/4 by 7-1/2 inches). American modular brick is:
3-5/8 by 2-1/4 by 7-5/8 inches (92 by 57 by 194 mm) when 3/8-inch joint is used.
3-1/2 by 2-3/16 by 7-1/2 inches (89 by 56 by 190 mm) when 1/2-inch joint is used.
The standard American modular brick used with a 1/2-inch joint is so close to the metric
modular brick that it can be used with only a slight variation in joint thickness during field
installation. Three vertical courses of metric modular brick with 10 mm joints equals 201
mm, which is rounded to 200.
Other sizes of metric brick are identified inGraphic Standards.
A standard American "8-inch" block is 194 by 194 by 397 mm for use with mortar joints.
A nonmortar joint stacking block is usually 203 by 203 by 406 mm. GSA has used 190 by
190 by 390 mm metric blocks on some projects, which is the size that companies shown in
the Product Information section responded to. The National Concrete Masonry
Association may set a size standard in the future.