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My dryer vent is installed only a few inches above grade, as shown in this image.

enter image description here

I'd like to fix the grading around the house but I can't raise the grade here because of the vent. Short of rerouting the vent indoors, are there any reasnable options for extending it outdoors?

I was hoping to use 4" PVC to extend it upwards by a foot or so, like the photo below. It would need a rodent guard and draft blocker. Are there any issues with this approach?

enter image description here

EDIT: One suggestion is to route the dryer vent through the rim joist. The photo below shows the vent on the interior. It goes through what used to be a narrow window. The room joist sits on top of the window frame so moving the vent to the rim joist would raise the vent by about 8". That's certainly better than what I have now. One practical issue is routing the vent behind the gas line, though it could possibly be moved horizontally to avoid that. This whole area is a mess!

enter image description here

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    It might help to include a picture of what you actually have installed in addition to the pic of what you're looking to do.
    – FreeMan
    May 13 at 15:37
  • Thanks! I edited the post with a photo. May 13 at 16:08
  • What gas line? Are you talking about that metal duct pipe which presumably carries exhaust or HVAC air?
    – MonkeyZeus
    May 13 at 20:21
  • Mystery somewhat solved: it looks like there used to be a vent through the rim joist. The previous owner added a bathroom in the basement and it looks as if it's located where the dryer used to be. When the moved the dryer to it's current location, they took the easy route and vented it through the old window instead of through the rim joist. So it at least seems possible to do it that way, though it would be a serious PITA to do it. May 13 at 21:47

2 Answers 2

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You can, but you shouldn't.

PVC has a maximum operating temperature of 140°F. The air coming out of the vent can hit 180°F especially if you have a gas dryer. Your solution might be fine if you have an electric dryer but if the next owner comes in and hooks up a gas dryer all willy-nilly then that could be problematic.

Additionally the surface of PVC will actually attract more lint than metal because it has more imperfections further increasing the fire hazard.

Lastly, consider how the heck you're going to connect the PVC. Based on the picture it looks like you're hoping to just insert it into the hole. Well good luck cleaning the lint off of the PVC lip every week.

Realistically, you should look into 4 inch HVAC ducts and joints. You can install the existing rodent guard at the end of the pipe. It's just galvanized steel so it will rust so you should consider painting it with a high-heat rust-proofing paint like Rust-oleum Ultra High Heat.

The addition of two elbows shouldn't be an issue assuming you adhere to this:

The maximum developed length of a clothes dryer exhaust duct shall not exceed 35 feet from the dryer location to the wall or roof termination. The maximum length of the duct shall be reduced 2.5 feet for each 45-degree (0.8 rad) bend, and 5 feet for each 90-degree (1.6 rad) bend. The maximum length of the exhaust duct does not include the transition duct.

Source


Regardless of material I think you will find it to be an eyesore and end up wishing you just re-routed it.

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  • Thanks for your input! Aesthetics aside, it sounds like using metal duct would be acceptable. I would love to reroute it but have no idea how to do so without it turning into a huge job. The vent is installed right below the main floor so raising it would require routing up into the wall cavity of my bedroom. I'm definitely open to suggestions! May 13 at 18:49
  • @RedSpikeyThing Yeah, brick and cinder block aren't exactly trivial to drill a 4 inch hole. Behind the brick there should be a rim joist which is accessible from your basement. Could you take a picture in your basement where the current exhaust is? It would cost you upwards of $1,000 to convince a professional to do it for you. Albeit a 4 inch hole saw costs about $60. If you're patient and cool the end of the hole saw with some water then you could drill your own hole somewhere else.
    – MonkeyZeus
    May 13 at 18:56
  • Oof. I'm actually not convinced that going through the rim joist would give me enough clearance. May 13 at 19:14
  • @RedSpikeyThing I cannot confirm nor deny your situation because you have not provided a picture. My rim joist is 10 inches tall and was perpendicular to my floor joists so I had zero issues drilling a 4 inch hole. If it was parallel to my floor joists then it's technically called an end joist.
    – MonkeyZeus
    May 13 at 19:16
  • Fair enough! I edited my original post to include a photo of the interior. May 13 at 20:01
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Code-wise, I don't know if what you want to do is legal or not. However, I see a potential practical issue, so I think it's likely that code might forbid this.

I can see that curved vent pipe becoming clogged with lint, especially if it's a bit of a run from the dryer. There might not be enough air pressure to push all the lint up the pipe & out, so some settles in the bottom. The more lint that settles, the more pressure it takes to push the new lint past it, so the more settles. Vicious circle until the vent is completely blocked.

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  • I checked my local building code (Ontario) and it's surprisingly lax. I couldn't find anything about this at all. Your point about lint is a good one. I can keep an eye on it and revisit if it becomes a problem. May 13 at 16:57

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