Structural Protection of your building

Structural timber protection

When timber heats up during a fire, the material starts to burn at the surface, forming a layer of char. During the fire, the charred depth will gradually increase. The charred material has no strength left, and also the pyrolysis zone (between the char and the still unburned wood) has a very limited mechanical resistance. Therefore, the remaining cross-section of the timber element gradually reduces, and at some point, the load can no longer be carried and the element will collapse.

The fire resistance can be improved by applying fire protection. This beneficial effect comes in two ways:

• The fire protection will delay the heating up of the timber, therefore postponing the start of the charring process.

• Once the charring starts, the fire protection will slow down the speed of the charring ( ‘charring rate’ ).

Promat offers board and paint products that have been tested and assessed by independent institutes. The assessment report states the time that the fire protection system delays the start of the charring, as well as the slowed-down rate of charring that occurs during more prolonged fire exposure. With these data, the engineer can calculate the effectively remaining cross-section of the timber element after a certain fire exposure and check that it is still able to carry the loads.