Horizontal vent pipes above or below insulation in attic?
Phil_in
| Posted in General Questions on
This seems like a simple question but I’m struggling to find a clear answer. I’m redoing the plumbing vent pipes in the attic of a ranch home that will get blown in insulation afterwards. Is it better to run the horizontal pipes below where the top of the insulation will be or above it?
On one hand, I lean towards visibility and accessibility if there were ever any issues. On the other hand, its a small attic and having them out of the way would be helpful. I’m guessing that having them insulated might also have some value. I’m in northern Indiana so things get cold but not that bad.
Thanks for any guidance.
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Replies
The only reason to worry about it at all is that in very cold weather, frost can build up in the vent pipe, though it's supposed to be large enough that it won't clog. So there may be a slight benefit to keeping it under the insulation. In practice, I've only seen horizontal runs in the attic up close to the rafters.
Thanks much, Michael. That makes sense to me.
Mainly, its nice to know that future remodels won't require as much insulation excavation.
cheers