What is the intumescent strip?
The intumescent strip – sometimes called a seal – is just one of the key components in a fire door. Running around the edge where the door meets the doorframe, it helps to trap the smoke in the area, preventing it from spreading, as well as assisting in keeping flames from spreading beyond the door.
The strip also expands when there is a fire, providing extra protection by filling out the gap around the door. With low friction fibres, the seal can also aid in the door closing effectively to form the seal.