masonry control & expansion joints
A masonry expansion joint is a complete break in the masonry wall to allow for the entire structure to move under loading, temperature related expansion/contraction, etc. This allowed movement helps prevent distortion and cracking. The purpose of a masonry control joint is to allow free movement while maintaining the weathertightness of the construction. Masonry expansion material is most commonly a pre-manufactured rubber profile product but standard cork, self-expanding cork, closed cell neoprene sponge, rebonded rubber, and pvc are available as well for unique or specialty applications.
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A masonry control joint is a continuous groove formed or cut into a masonry wall forming a plane of weakness to control the location of the eventual cracking. Due to it’s massive and rigid nature; drying shrinkage, thermal stresses, and structural movement, control joints are used to plan and hide the look of an uncontrolled crack. Also, control joint anchors are often utilized at the control joint to help keep the wall from expanding and to maintain it’s purpose as a control joint only.
Movement joints are commonly spaced 100-125′ along unbroken masonry walls and as follows:
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-changes in wall height or thickness
-near corners
-on one side of openings < 6′
-on both sides of openings > 6′
-at columns, pilasters, and wall intersections
Uncontrolled crack