This Hole May Be the Biggest Air Leakage Site in Your Home
I'm talking about the hole the plumbers cut for the bathtub drain. If you have a bathtub sitting on a floor over an space like a vented crawl space or unconditioned basement, this hole allows air to move freely between inside and out. Often, the air these holes bring in is not the kind of air you want in your home. Nor are the critters.
I've spent a lot of time in crawl spaces over the past decade and have seen a lot of bad stuff there. It's not the kind of stuff you want to invite inside either, yet your bathtub hole gives easy access to the bad air, the critters, and the moisture.
Why is this hole there? You might think it's to accomodate the bathtub drain, which connects to the tub in two places and runs horizontally right at about the level of the subfloor. But maybe there's another reason. Look at the size and shape of that hole. Think about how big a six-pack of beer is. That's it! It's the six-pack hole, cut big enough so the plumber working down below can get a six-pack handed down through the hole.
OK, not really. Even though I did have trouble with plumbers when I was building my house ten years ago, that's not really the reason for the hole. It's just to accommodate the plumbing. There are some very good plumbers doing work on homes, and my grandfather was one of them.
You might think that maybe your house didn't get such a big hole. Or maybe the builder had the hole sealed up before they finished the job. You're probably wrong, though. I've got dozens and dozens of photos of bathtub holes. Here are three more, for your viewing pleasure.
And yes, they're still doing it. The one below is from a recent addition.
You may think that the nasty crawl space air can't move freely into the house because the bathtub will stop it. Yes, a bathtub, whether made of cast iron or fiberglass is a pretty good air barrier and won't let the air pass through. So the air does what it does best and finds other ways to move.
Look at the photo of that last bathtub hole. Notice the open wall studs. The air moves into those spaces and finds all the openings available to come out into your home: under baseboards, through electrical outlets and switches, behind cabinets... Air, being a fluid, is really good at finding ways into your home.
Now I guess I should apologize. If your home has a bathtub over a crawl space, you probably won't be able to rest until you've been down there and seen how bad it is. If you venture into that danger zone, please be careful. I've seen things much worse than the camel crickets shown above.
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