Ok I've read conflicting stories, but I was up in my attic today and there is a bunch of what I'm assuming is rock wool insulation everywhere. Should I remove this before adding new insulation? What if there is a leak or seepage somewhere underneath it?
How old is your house anyway? Rock wool insulation is a relatively new type of insulation and only some is suggested for thermal insulation; depending on its age or whatever date any renewal was done up there, it may be cellulose - or some other form of insulation. You may be able to get it all out with a ShopVac but nothing beats a good scoop, gloves, mask - and a few dozen garbage bags.
If there is any question of damp or wetted insulation, remove it. If you get lucky, some insulation will dry but not for weeks. Ideally, you want a dry attic and, although that's a tall order in most places, wet or damp attics don't do anyone any favours. Any plan to go up there, get a good look around and seeing every nook and cranny (by moving the existing insulation) is, IMO, a good plan. Only then wil you be sure that you have either found or missed the leak causing the damage in the first place.
"Ignoring it won't make it go away"... I'm not saying you are - I'm talking from personal and professional experience here (we are in the water damage business). You have to have a Sherlock Holmes attitude sometimes and never rest till you find the source of the leak, but it's neither obvious nor easy up there; the consolation is that once fixed, you can do away with cables, pellets and any other symptom-treating methods that are good for now - but not permanent.
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