Boractin is boric acid. It usually lasts about 8 months when applied. If exposed to water or heat it won't last at all. It is not water repellent and heat will usually destroy it. The overall time it could last in an attic is one of those things that you just can't really determine. If it works, and controls what you are trying to control, then that's all you can hope for. It won't last forever, but is one of the longest lasting dusts with the lowest toxicity available.