What are Movement Ratings?
A movement rating is an attempt to categorize the anticipated range of horizontal change in a joint opening. For example, a 100mm nominal joint which is expected to have a range of horizontal movement of plus 50mm or minus 50mm, could be denoted as (100mm+/- 50%) Alternatively the actual physical movements may be defined – 100mm ±50mm. Joints designed for thermal movement will typically have a movement rating in the +/- 10% to +/- 20% range. Joints designed for seismic movement will typically have a movement rating of +/- 50% to +/- 100%. Joints designed for windload movement will normally be rated as seismic.
