Ask the Expert Question-and-Answer Archive

by Ron Joseph

February, 2004

3-Hour Intumescent Paint

Q. I am overseeing the construction of a performing arts theater. The contract documents require a 3-hr intumescent paint to be applied at the steel trusses that span the auditorium. This is applicable where mechanical ducts run between diagonal bracing and above the balcony and private boxes. The contractor claims that there is no such product for a project of this size. The contractor claims that this is only applicable to large bridge projects. Is the general contractor correct? The general contractor would rather use a "CAFCO" product.

A. Recently I spoke to someone at the UL labs concerning fire ratings. He told me that ratings are based on actual tests that are performed on different structural configurations and that you might not be able to simply find a coating that has a generic 3-hour rating. In other words, you would need to find a coating manufacturer who has run performance tests on a specific coating formulation under specified test conditions. your contractor might be giving you good information, but I don't have sufficient knowledge to asisst you further.

UL has published several documents on this topic and you might want to visit their website and download applicable information. In addition, you might want to speak to the technical folks in their intumescent lab.

If you choose to do this I would be grateful if you would please get back to me and let me know what you find.