2.9 : 建筑物中的移动缝

Slight movements in buildings can occur during the expansion of building units exposed to moisture or the upward heaving of foundations when water in the soil expands while freezing.

Movements may form cracks in the building; movement joints such as working joints, structure enclosure joints, surface divider joints, and building separation joints are provided to avoid this.

Working joints are used in shingled roofs, where small strips are assembled in an overlapping pattern, tolerating slight movements without any distress.

In a cavity wall, the soft joint provided under the shelf angle supporting the non-structural exterior wythe is an example of a structure enclosure joint.

Surface divider joints include isolation joints, expansion joints, and control joints.

When new additions are made to an existing building, isolation joints are provided, enabling the movement of the new materials without impacting the existing building.

Expansion joints are open slots designed to allow the expansion of building materials, while control joints are lines of weakness created where cracks may occur when building materials shrink.

Lastly, building separation joints subdivide complex building structures into discrete segments that can be independent of each other's movements.