It is important to any masonry project that the units themselves be suitable for their application. This is something carefully considered by designers but when it comes to the construction phase, it is important that a clear set of guidelines can be referenced when deciding which units are acceptable to be placed in the wall.
The purpose of this page is to provide insight and recommendations on specifying masonry unit quality control that addresses designer concerns while also referencing CSA Standards.
This page is part of a larger series of specification examples meant to highlight cases where vague or poorly written items have lead to issues on masonry jobs across Canada.
The information contained here is intended to serve as educational content for designers, specifiers, or contractors. It is not to be relied upon for formal technical advice, as masonry projects may have details and considerations that are unique to a particular project and may be beyond the scope of the content of this page.
How the specification typically appears:
X.Y.a Install masonry with exposed faces having straight arises and free from stains, chips and cracks. Do not use chipped, cracked or deformed units in exposed work. Replace damaged masonry units in exposed work.
Points to consider related to unit appearance:
Units containing cracks or other defects that would negatively affect the strength, finish, or durability of the masonry construction, or that would interfere with the placement of the unit in accordance with the masonry construction standard CSA A371-14, should be removed and replaced. However, minor cracks or minor chipping due to usual manufacturing methods and customary methods of handling in shipment and delivery are acceptable within certain limits.
CSA masonry standards for concrete units, CSA A165-14, and for clay brick units, CSA A82-14, each contain requirements for an allowable or maximum level of chippage or cracking in the masonry units acceptable within masonry construction. Each standard independently defines the maximum acceptable size of chips and cracks, and the maximum percentage of exposed units permitted to have chippage or cracks. Units exceeding the limits established by the standards should be removed and replaced.
In addition, the standards indicate that the faces of units to be exposed shall not have other imperfections affecting the appearance of the masonry when viewed from a distance of 6 m under diffused lighting, when the surfaces are constructed with standard masonry units; more restrictive requirements may be applied where units manufactured with a higher degree of precision and a smaller permissible variation in size are used (i.e. Type X clay brick units).
It is important to recognize that light sources that act coincident with a wall’s surface will cause minor imperfections to appear worse for a wall that is constructed within the limits referenced in the CSA A371-14 standard.
Suggested changes to the specification:
X.Y.a Install masonry in accordance with CSA A371-14. Remove chipped, cracked and otherwise damaged concrete masonry units in accordance with CSA A165.1-14 Remove chipped, cracked and otherwise damaged clay brick units in accordance with CSA A82-14
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