Concrete encasement

Until the late 1970s concrete was by far the most common form of fire protection for structural steelwork, Figure 27 shown below.  However the introduction of lightweight, proprietary systems such as boards, sprays and intumescents has seen a dramatic reduction in its use. At present concrete encasement has only a small percentage of the fire protection market with other traditional methods such as blockwork encasement also used occasionally.

The principal advantage of concrete and blockwork is:

Durability - these robust encasement methods tend to be used where resistance to impact damage, abrasion and weather exposure are important e.g. warehouses, underground car parks and external structures.

The principal disadvantages are:

Cost - concrete encasement is normally one of the most expensive forms of fire protection.

Speed - time consuming on-site.

Space Utilisation - large protection thicknesses take up valuable space around columns.

Weight - building weight can increase considerably.

Information on thickness of concrete encasement for specific periods of fire resistance can be found in Guidelines for the Construction of Fire Resisting Structural Elements.