TABLE OF CONTENTS Masonry exteriors suggest beauty, stability, security, and fire resistance. The thick loadbeaiing barrier walls of yesterday provided all four, but today such walls are uneconomical to build. Since the mid-twentieth century, those monumental walls have been replaced by single-wythe walls of concrete masonry units (CMU) and by brick-veneer walls, in which the thickness of brick is less than 4 in (10 cm). The old massive brick walls and today's single-wythe CMU walls are barrier walls, whereas brick veneer, discussed in the next section, is an example of cavity wall construction.
Solid masonry walls made of brick or single-wythe CMU can suffer from the three main causes of distress in exterior walls discussed in Sec. 13.1.1: fa ade disintegration, problems stemming from thermal and moisture movements or movement of building structure, and water penetration or condensation.
The most common signs of damage in masonry walls are deterioration of joint mortar and delamination and cracking of exterior brick or masonry units. Crumbling and cracked mortar is the result of freeze-thaw cycles and the attack of harmful chemicals. The aging process accelerates if the mortar is not sufficiently compacted, or if the joint profile encourages water to linger there. When this water freezes, it damages both mortar and brick,
Disintegration of brick most often involves delamination and cracking of the exterior brick surfaces as a result of weathering and freeze-thaw cycles. The speed of this process depends greatly...
