We are finishing documents for a publicly bid project and Thermax is being used in the exterior wall cavity. Does anyone know of any products that would be considered equivalent? We need the flame spread to be 25 or less.
Thanks!
Why do you have a restricted flame spread IN a wall cavity? Should not be required.
Thermax’s flame spread is rated for exposed insulation applications, and is one of the few plastic insulations so rated.
I was told that was a project requirement.
Foam plastic insulation located within an exterior wall of Type I, II, III, and IV buildings must have a flame spread of 25 or less per IBC (2006) Section 2603.5.4 as tested IAW ASTM E 84. The 2009 IBC allows testing IAW UL 723.
Also keep in mind that the exterior wall assembly needs to have been tested IAW NFPA 285, unless the building is a single story, per IBC Section 2603.5.5.
If you are including sheathing and barrier, why not include XPS? See related Discussion Forum thread “Polyisocyanurate Insulation R-Value”. There are plenty of manufacturers and it’s a proven system. If the Thermax comes in cheaper, it seems like you have provided fair competition.