Page 362 - IGC BOOK

Flame-retardant paints and intumescent paints are also available. These bubbles up to protect
the timber beneath.

Plastics
There are two types of plastic:

• Thermosetting plastics, which are formed by the action of heat and compression – these
will not soften and melt when involved in a fire but will decompose.
• Thermoplastic plastics, which are moulded into the required shape by heating and on
cooling, remain in that shape – if involved in a fire they will melt and flow.
Plastics are used primarily in building services and surface fascia’s. The principal hazards they
present in fires are the dripping of molten plastic and giving off products of incomplete combustion
in the form of toxic smoke.

Compartmentation

Compartmentation is the process or design of isolating zones of a building to ensure a fire in one
area does not spread uncontrolled to another area. The design technique of compartmentation is
not only applied to roof voids and other concealed spaces, but can be applied to most areas creating
specific fire protection zones within a building. The potential for such fire protection zones is in fact
inherent to the building design i.e. the walls or rooms of the structure - if suitably designed,
constructed or modified - create the boundaries for compartmentation. A simplified analogy is that
the property has been divided up into 'boxes', each of which intend to inhibit fire growth; again, in
simple terms an example is the difference between a room with either on open or closed door. The
division of a building into these fire zones offers perhaps the most effective passive means of
limiting fire damage.

Properties of Intumescent Coatings

Intumescent coatings provide an appearance similar to that of a paint finish, and remain stable at
ambient temperatures. However, in a fire situation, the increase in temperature causes a chemical
reaction, and the intumescent coating expands to many times its original thickness. This provides an
insulating foam-like coating or ‘char’ which protects the substrate. In the protection steelwork, the
intumescent coating is designed to insulate the steel and prevent the temperature of the steel from
rising above a certain point. This in turn protects the steel and other materials from the high
temperatures of fires, thus preventing or retarding structural damage during fires. Intumescent
coatings are also used on wood but work in a different manner; timber structures are more
susceptible to the surface spread of flame and heat propagation. Intumescent are designed to
reduce heat propagation, and reduce the spread of flame. Intumescent coatings are made of a

ENSIGN | Unit IG2 – Element 10 –Fire 17