3.8 Masonry—Assembling the Pieces 
       and Ingredients into a Building

Working with the components as they are—to build a structure 
that manages movement, water, fire, and sound

Masonry Works with the Entire Building Structure  
Not just a stack of bricks

Using compression and managing all other forces 
Design improvements require increased knowledge

For most of the history of masonry construction, the thickness and heights of masonry walls were done by rules—based on experience. 'This made for a very tall, skinny triangle. A common rule went, “the top story is two bricks wide, the next story down three, and adding a brick-width per story down to the basement.” 'This would produce walls up to twenty feet thick. Since this rule, in many cases, produced significantly overbuilt walls, not a lot of knowledge was necessary. However, starting in about 1950, acceptance of engineering advances, and the introduction of steel into masonry construction produced entirely different ways of calculating the “right” wall height and reinforcing—and made comparatively thin wall assemblies the norm. 'This, however, does require some understanding of the structure of a wall so that you know how to build it and how to brace it in a temporary mode until the building is finally completed.

Wall strength varies with direction of stress

As stated in a number of places previously, masonry walls are very strong in compression. For example, if a wall is intended to support a floor above, it will be very strong if the floor is placed entirely over the top of the wall. However, typically, the floor structure favors the interior side of the building. 'This is called “eccentric loading” and tends to make the outboard face of the wall bow out slightly—causing tension at the bulged-out part of this bow. 'This means the wall must be vertically reinforced and its reinforcing grout cured, before it can take this eccentric load.

Wind and earth loads—timing matters

Other loads imposed on a wall are wind above ground, and earth below grade. Walls are weakest against horizontal forces that produce tension and bending (it is easier to push the top over, or the middle out)