The plumber fixed the copper shower pipes though an adjacent closet area which had b urst. Everything is now ready to close back up. My question is, is it alright to cover the hot and cold pipes with batt insulation? Should the pipes be left open ( no insulation around them) behind the access panel? Of course what I don't want is the insualtion to get wet, from condensation on the cold pipes. Should the insulation cover the pipes thoughout the walls?

I am having an intermittent problem that is baffling me. Granted, I'm not a plumber but bear with me. I own a 2 story home that has two full size bathrooms on the 2nd floor, 1 half bath directly under the shared wall between the 2 full size bathrooms, and then another half bath in the basement. I had this water stain on the ceiling of my main floor half bath and decided to cut a hole in the ceiling to see what was leaking. I found that the subfloor around a particular 1.5" pipe was wet, and after some measuring I determined that pipe went up through the shared wall. I cut a hole in the drywall at this pipe on the 2nd floor, and found it not to be a drain for the toilets or the sinks. It went along the wall at a 45° angle and eventually went up to the attic (after cutting numerous holes in the wall trying to trace the leak). There was a Y fitting midway up the wall that was leaking in what I determined to be the vent pipe. So I cut the old one out and put a new one in. I repaired the drywall but never got around to patching the ceiling. Well yesterday I heard my wife flush the toilet upstairs and then I heard fast dripping water. Yep, the half bath on the main floor had water dripping pretty good from that same pipe. Needless to say either my Y-coupler repair was bad or its now leaking from another location. My main concern is how is water backing up into the vent pipe? This Y-coupler was midway up the wall on the 2nd floor, meaning there is a few feet of head to push water up that high. She flushed the toilet two more times and each time water came leaking down the vent pipe. Running the water in the bathroom sink or taking a shower did not result in a leak, neither does running the washing machine. I flushed the toilet multiple times today and it is not leaking, so it seems to be a random thing (except when it occurs it happens consistently until it sits for awhile). For those experience in this area, give me some suggestions or descriptions on how water is backing up into this vent pipe and how I can fix it (with exception to the obvious repair to the Y-coupler). If you need more info let me know