sentences:  Where fire-resistance rated wall assemblies, be they masonry or drywall, meet the underside of the floor slab above, a movement joint results, which can be subject to compression, as the freshly placed concrete cures and shrinks all over a new building.This joint must be firestopped in a flexible manner.For concrete block walls that are not load-bearing, the contractor is often instructed to stop the wall about 25mm short of the slab above.