Cross Section of a Masonry Wall
(44 St.George St. - SW corner, now repaired) |
Background
Until recently, you could find an excellent "cross section" of a solid masonry wall here on the campus. Unfortunately, shortly after this photo was taken, this ragged wall was repaired. However, this photo illustrates a solid masonry wall that is typical of walls built prior to the 1950's. Notice the numerous gaps and cavities where the mortar incompletely fills the joints between the wythes (collar joints) and between the courses (bed and head joints). The existence of such cavities provides numerous pathways for the leakage of air. Further, while such walls have a rather large thermal mass, they offer relatively low resistance to heat flow. The exterior face has well-tooled and complete joints. These exterior bricks were usually the best-fired bricks in the kiln, while weaker, or poorly-fired bricks known as "seconds" were used in the inside of the wall. These "seconds" can be re-used, but should only be used in protected indoor conditions. |
