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.

If there are any questions or concerns regarding masonry design or construction, CMDC offers technical assistance to our supporting members, as well as the design community.

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.

In the case of natural stone masonry, additional care and attention may be needed. It is recommended that designers specify the construction of a “mock up” or sample panel, as a segment of a masonry assemblage or stand-alone panel (see CSA A371-14, Annex A) before the start of general masonry construction. And as previously stated, evaluation of workmanship should be done by viewing the assemblage from a distance of 6 m under diffused lighting. Construction that otherwise falls outside the CSA standards should adopt manufacturer recommendations and follow any other requirements from the authority having jurisdiction. Workmanship requirements described in CSA A371 may be adapted to other types of masonry-related construction; however, designers should be aware that the provisions contained in the CSA standards have been written within the context of Unit Masonry Construction, as defined in CSA A371, only.