Effectiveness of flame retardant treatments for fire reaction of pine linings and coverings in buildings
Abstract
Although widely used in construction in Brazil for ceilings and wall or partition claddings, some Pinus species exhibit poor fire reaction performance, commonly classified as V-B according to the criteria of ABNT NBR 16626:2025 and the fire protection regulations of Fire Departments in several states. This limitation restricts their use in buildings where fire safety is a critical requirement. The present study aimed to compile the effectiveness of different flame-retardant treatments in improving the fire reaction performance of these woods. Samples of untreated Pinus boards and boards treated with various methods were tested, including non-intumescent varnish, intumescent varnish, intumescent paint, immersion in flame-retardant solution, and autoclave treatment with flame-retardant product. The tests were conducted in accordance with ABNT NBR 9442:2024 (flame spread index) and ASTM E 662:2021 (smoke optical density). The results showed that some of the tested treatments had negative or negligible effects, meaning they worsened the fire behavior or did not provide significant improvement. However, certain treatments enabled the reclassification of the wood to Class II-A, demonstrating its potential for use in more demanding applications from a fire safety perspective.