Joint (building)

When one or more of these vertical or horizontal elements that meet are required by the local building code to have a fire-resistance rating, the resulting opening that makes up the joint must be firestopped in order to restore the required compartmentalisation.

Firestops must be able to demonstrate the ability to withstand operational movement prior to fire testing.

Firestops for such building joints can be qualified to UL 2079 -- Tests for Fire Resistance of Building Joint Systems.

Timing is also important, as freshly poured concrete shrinks [1] particularly during the first few months of a new building, potentially causing joint size changes.

Where vertical fire-resistance rated wall assemblies 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.