Reaction to fire tests — Spread of flame — Part 4: Intermediate-scale test of vertical spread of flame with vertically oriented specimen

1.1 This part of ISO 5658 specifies an intermediate-scale method of test for measuring the vertical spread

(upward and downward) of flame over a specimen of a product orientated in the vertical position. A measure of

lateral spread can also be obtained. It provides data suitable for comparing the performance of materials,

composites or assemblies, which are used as the exposed surfaces of walls or other vertically orientated products

in construction applications. Some products with profiled surfaces can also be tested with a modified procedure

representative of the end-use conditions of the product.

1.2 Upward flame spread is not limited to surfaces which are vertical. It is recognized that an enhanced form of

upward, wind-aided flame spread can also occur on surfaces at an angle greater than 20° from the horizontal

without any external ventilation. This type of flame spread can occur in both planar sloping surfaces and stepped

surfaces such as stairs. Flame spread in these situations can become very rapid and can cause serious problems

in escape ways such as staircases. When assessing stepped or sloping surface materials, it may be more

appropriate to use a vertical fla