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My wife and I are having a home built and they’ve nearly completed insulating and have installed the vapor barrier. The vent pipe to the kitchen sink is located on an exterior wall and walking through yesterday I noticed the installers had insulated next to the T11 behind the vent pipe but not over the pipe which leaves the stud cavity in this 2×6 wall only half full of insulation. Was wondering if this is a common practice? Since the vent penetrates the roof and will probably be full of cold air wouldn’t leaving it uninsulated next to heated space cause a cold spot on the wall? As the drain for the kitchen sink is located below this area, no water will be flowing through it so freezeup shouldn’t be a problem. Would appreciate any opinions on this. Thanks much!
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IMHO, as much plumbing as possible should be run in interior walls in cold climates. Where I had to supply the kitchen sink in my own house, I run the lines close to the inside, used nail strike plates, and insulated BEHIND the pipes.
My concern was that when it is 70F inside and -40F outside, the middle of an insulated wall will get down to 15F. Actually a bit lower because there is wind on the outside but kitchen cabinets on the inside.
Possibly your builders were reacting to the same concern. Or maybe just being lazy. But less insulation inside of a pipe can be a good thing.
Yes, the heat loss through the bay will be a bit more, but a tiny effect overall. Poorly sealed penetrations are a much bigger issue in heating costs. I'd consider sealing where the vent pipe penetrates the top plates with closed-cell foam (like is used under the bottom plate). -David
*It might be common, but even if it is, it's wrong.At least in theory, that section of wall be a little cooler because of the vent, but leavoing out insulation is a bad idea, especially in a high moisture area like a kitchen: potential for lots of condensation.Make sure it's filled before they close the wall.
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My wife and I are having a home built and they've nearly completed insulating and have installed the vapor barrier. The vent pipe to the kitchen sink is located on an exterior wall and walking through yesterday I noticed the installers had insulated next to the T11 behind the vent pipe but not over the pipe which leaves the stud cavity in this 2x6 wall only half full of insulation. Was wondering if this is a common practice? Since the vent penetrates the roof and will probably be full of cold air wouldn't leaving it uninsulated next to heated space cause a cold spot on the wall? As the drain for the kitchen sink is located below this area, no water will be flowing through it so freezeup shouldn't be a problem. Would appreciate any opinions on this. Thanks much!