If you want to make a window in the bathroom yourself, you must have good knowledge and skills in this area, if you want to do the job qualitatively. in this you can help hphtools.com. If you, with proper knowledge, do your work well and qualitatively, the problem with drafts will be solved and will not come back to you for a very long time. I would have hired workers if I were you, but everyone has his own opinion on this matter.