Lessons learned in masonry: Presenting 10 useful tips from the field

A good concept used by estimators is the rule of 200-mm (8-in.) heights. If your foot dimension is an even number, then the height to stay on module is either the even foot or the even foot plus 200 mm. If the foot dimension is an odd number, the height to stay on module is the foot dimension plus 100 mm (4 in.). Any other height and costs increase.

This concept works for brick as well. On a recent dormitory project in Ohio, a plan review noted window dimensions were slightly off module. Shifting them fractionally preserved the design intent, but saved over $10,000 on the bid cost for reduced cutting of brick.

Tip 4: Locate movement joints on the drawings

Some of the more popular questions the author’s firm (the International Masonry Institute [IMI]) receives revolve around movement control. Concrete products, including concrete masonry, tend to shrink as they cure and lose moisture. Clay masonry expands with moisture and experiences dimensional changes for thermal expansion as well. It is very helpful to recognize that and note on the drawings, locations and provisions for movement control. Placing this only in a specification can lead to confusion and potential cracks in the masonry system. Control joints should be placed at various intervals for concrete masonry, as it tends to shrink. Clay masonry should have expansion joints to allow small growth of the brick.

According to the Masonry Society (TMS) 402/602, Building Code Requirements and Specification for Masonry Structures, the masonry code referenced by the International Building Code (IBC), the coefficient of thermal expansion for clay masonry is 7.2 x 10^-6 mm/mm/C (0.000004 in./in./F), which works out to roughly a 13 mm (½ in.) of growth over a 30-m (100-ft) span with a 38 C (100 F) temperature difference.

Tip 5: The mason contractor should not locate the movement joints

While IMI and other groups offer advice on standard spacing for control and expansion joints, and review specific projects to make recommendations for movement joint location, the ultimate responsibility is with the designer of record. Decades ago, the masonry building code understood this need. The code now contains provisions requiring the designer, not a contractor or other source, to locate and detail provisions for movement control in masonry. While trained mason contractors are an asset to the project, they may not know the design intent or how the walls were structurally designed.

Properly designed masonry works with the adjacent materials as a system to control moisture penetration, vapor, airflow, and energy transfer. Most problems in the enclosure occur where two dissimilar building materials meet.

Tip 6: Pay extra attention to where dissimilar materials meet

It is important to take great care where dissimilar materials requiring installation by different trades meet. Specifications and contracts should carefully state responsibilities.

Putting masonry units together as a system is the next step toward high performance. Masonry walls fall into the general categories of barrier, cavity, or drainage and rain screen walls, which are a refinement of the cavity wall system. The most common issue with any masonry wall system is water penetration. Building professionals tend to assume moisture intrusion is a result of wind-driven rain, but designers should pay attention to other sources including rising damp, vapor diffusion, and airborne moisture that moves due to differences in temperature and pressure. With the rise in the use of air and moisture control systems and layers, there is an increase in moisture problems due to uninformed or incorrect placement of the air and vapor barriers, or unintended consequences of trapping moisture or vapor, and location of the dewpoint.

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