I've been talking with my fire marshal lately about this longstanding gray area. I have natural fiber curtains that are FR treated. The most recent cleaning and re-treatment happened in September 2014. Usually, when I buy fabric I get a certificate guaranteeing the treatment for one year and saying it'll likely last longer but testing is recommended. In other cases, like the 2014 treatment, I see a cert with only a date of application and nothing about longevity. Until recently, I've been the only one bugged by this and my AHJs haven't cared one bit (even when I bring it up) as long as they have a cert on file. I suspect that's true in many or most localities. We have a new fire marshal now, on the job less than a year, and he has taken more of an interest in this issue. I'm glad, because I want a more firm and reliable code based ruling. I don't like being surprised with "oh, I was reading the code today and noticed I have to shut down your show". I recently brought a sample from the same batch of 2014 treated material to the fire station and we did the NFPA 705 field test. It went really well, so we're both unofficially satisfied that the 5 year treatment interval I've historically used is at least adequate. But NFPA 705 is explicitly not a reliable substitute for 701. I personally see the language in 705 allowing room for the AHJ to make a judgement, but that isn't something my guy is presently comfortable with, so we're both researching what others are doing with the issue. So, from those of you who have a direct relationship with your AHJs, how are you handling this and what's the rationale? Have you arrived at a code or other research based solution for compliance that doesn't involve re-treating annually or replacing with IFR material?