Relieving Masonry's Distress Northampton MA

Source: MASONRY CONSTRUCTION MAGAZINE
Publication date: September 1, 2000

By J. Gilbert Kaufman

Many masonry buildings suffer distress. Proper design and detailing, in most cases, could have reduced the distress to acceptable levels or eliminated it completely. One common cause of distress is stress cracking of masonry elements caused by the absence or improper spacing of movement joints. The proper use of expansion joints or crack-control joints is not well understood.

We have produced thinner and lighter masonry elements in order to reduce both costs and weight. Older masonry buildings were far less prone to cracking since the thickness of the elements provided greater strength and resistance to tensile stresses. Modern thin masonry elements, however, are subjected to much higher stress from the same load since there is simply less material to absorb the load.

Often older mortars were of lower strength and sometimes of different composition than modern high-strength mortars. These softer mortars were more forgiving to building movements.

Proper design and adequate reinforcement can relieve tension without the use of control joints. The designer and contractor must therefore understand that movement joints are intended to provide relief from:

1. Differential movement at the foundation level.
2. Stresses resulting from thermally induced volume changes.
3. Differential movement between facing materials and backup materials in veneers or composite systems.

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