I am going to replace roof, but there is some type of mold on sheathing ?
Water and bleach?
John, I own a mold remediation company so to CYA let me preface this with a " if you have concerns you should hire a professional certified and/or licensed in mold remediation." That being said, if you are set on doing it yourself (I see that you are a contractor), there are a number of anti-microbials available on the market that are much much better than bleach and are no more than $20-30/gallon. If you're still looking to do this yourself, feel free to reach out to me with questions.