Sunday, 22 March 2015

Masonry Terminology

Construction terminology can be confusing, especially where masonry is concerned. Many terms unique to masonry construction can leave laypeople scratching their heads. In this post, we make sense of some of the terminology used within the masonry industry.

Masonry is simply an assemblage of modular units, which are usually either solid bricks or hollow blocks. Units are typically bound together with mortar made from sand, water, and cement. Other options for assembling the units also exist, such as dry-stacked masonry, where no binder is used, interlocking masonry, where the units fit together like puzzle pieces to provide mechanical connection to each other, and glued masonry, where units are bound together with a thin layer of adhesive.

A layer of a wall that is one unit thick is called a wythe, though the term leaf is also sometimes used. A row of units along the length of the wall is known as a course. Horizontal mortar joints are called bed joints and vertical mortar joints are called head joints



Masonry units can be laid in six different orientations, each of which has been given a name to differentiate them: stretcher, header, rowlock, soldier, sailor, and shiner. Stretchers are laid with the long, narrow side facing out and the long edge horizontal. Soldiers are also laid with the long, narrow side facing out, but the long edge is vertical. Headers are laid on their broad side, like stretchers, but have the small face exposed. Rowlocks also have the small face exposed but are laid on the long, narrow side.  Sailors and shiners are laid with the broad side exposed and the long edge vertical for sailors or the long edge horizontal for shiners.




Hollow blocks are typically laid as stretchers, occasionally as headers, and should never be laid as sailors or shiners. Solid bricks are also typically laid as stretchers, but headers, rowlocks, and soldiers are also pretty common, especially in older buildings. Sailors and shiners are rare in solid brick masonry, but have been used in the past to produce some interesting brickwork patterns. Masonry is strongest when loaded as a stretcher or header, so rowlocks, soldiers, sailors, and shiners are typically used for decorative purposes where the strength demand is low.

After the bricks have been laid, the mortar joints have to be finished. Mortar joints can be finished in several different ways to produce different aesthetics, as illustrated below.



The most common joints are concave joints (occasionally called bucket handle joints), which provide a finished look without negatively affecting the overall strength or ability to manage moisture. Flush joints work well for masonry that will be coated with parging or plaster because flush joints aren’t as likely to show through the coating as it ages. Raked joints are made by raking out some of the mortar before it hardens. This emphasizes the edges of the units and can create a good aesthetic. However, raked joints are generally weaker and more susceptible to moisture intrusion than most other joints. Extruded joints, also known as weeping joints and occasionally called skintled joints, are really just unfinished joints. The extrusion is formed from mortar that’s squeezed out of the joint when the brick is laid in place. Some people like extruded joints, claiming they give the brickwork a rustic look, while others feel extruded joints just look messy and unprofessional.

We looked at some of the different terminology used within the masonry industry, including the six orientations of a brick and nine different ways to finish mortar joints. In a follow-up post we will take a closer look at some of the many different patterns masonry can be constructed in.

References
BIA. (1975). Technical Note 2: Glossary of Terms Relating to Brick Masonry. Brick Industry Association, Reston, VA.
Brunskill, R. W. (1997). Brick Building in Britain. Gollancz, London, UK.
Hatzinikolas, M. A. and Korany, Y. (2005). Masonry Design for Engineers and Architects. Canadian Masonry Publications, Edmonton, AB.
Lloyd, N. (1925). A History of English Brickwork. Antique Collectors' Club, Woodbridge, UK.


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