Piers and columns

Q Is there a difference between a masonry pier and a masonry column?

A The terms are often used to describe any narrow vertical masonry element; however, they do have different meanings in the building codes.

In Section 1.6 - Definitions of ACI 530-05/ASCE 5-05/TMS 402-05 (MSJC 2005), a pier is defined as an “isolated vertical member whose horizontal dimension measured at right angles to its thickness is not less than 3 times its thickness nor greater than 6 times its thickness and whose height is less than 5 times its length.” A column is defined as an “isolated vertical member whose horizontal dimension measured at right angles to its thickness does not exceed 3 times its thickness and whose height is greater than 4 times its thickness.” A wall is defined as a “vertical element with a horizontal length to thickness ratio greater than 3, used to enclose a space.”

In summary, a column is not as wide as a pier or a wall because it cannot exceed 3 times its thickness. A wall, on the other hand, must be wider than 3 times its thickness. A pier overlaps the definition of a wall since it must be wider than 3 times its thickness, but cannot be wider than 6 times its thickness.

Copings and caps

Q A coping and a cap are often used interchangeably. What is the difference between the two?

Does the term coping refer to a masonry unit that extends beyond the face of the wall, and a cap is a unit that is flush with the face?

A The terms “cap” and “coping” are used to mean many different things. I personally prefer the definition for copings and caps provided in the Brick Industry Association (BIA) Technical Notes 36A. This document states, “For the purpose of this Technical Note, the word ‘coping' applies to the covering at the top of a wall, and the term ‘cap' refers to a covering within the height of the wall, normally where there is a change in wall thickness.”

Although many buildings are designed with copings and caps that are flush with the face of the wall, I do not recommend this practice, especially in parts of the country that experience freeze-thaw cycling. The purpose of copings and caps is to shed water away and prevent it from penetrating the masonry along the top of the wall.