I think even if it isn't actually required for ethics, it's probably good practice to have documentation outlining step by step procedures that you're applying to your research. Firstly, it'll help focus your mind and make sure that your methodology is sound - it might help you to identify flaws/omissions that you might otherwise have missed. Secondly, when it comes the administrative things, I'm a firm believer in having a defined paper trail that shows what you did, what you didn't do, and why. It can be useful for all manner of reasons.