I've been researching how to vent my basement dryer, using galvanized steel ducts. There are lots of things on Google that show how to do this under a normal situation, but mine is unique, and I can't find a good answer yet.

Normally one would drill a hole through the wall that faces the outdoors, and run the duct through there. But I can't because my walls to my house are stone, and I would never want to drill a 4 1/4" hole through it.

Instead, I'd like to dig a hole in the yard, where the vent will come through the basement cinder block, and then drill through the underground cinder block. This requires three 90 degree turns, but the total equation is less than 25' (counting 5' for each turn).

Is this ok (I follow Maryland code)? Will the weight of the dirt harm the steel duct when I refill the ground around the vertical duct? And which kind of cap should I use at the end (assuming this is ok to do in the first place)?

Hopefully this picture helps: enter image description here

  • Is that a floor above the dryer or something else? Commented Apr 24, 2019 at 19:21
  • @MicahMontoya Hi, yes, that is the ground floor of the house, and it is supported by the joists that are at the basement's ceiling.
    – Mark
    Commented Apr 24, 2019 at 20:34
  • If you have to do it via this route. Rather than backfilling install a window well type enclose with proper drainage instead of backfilling.
    – Tyson
    Commented Apr 24, 2019 at 23:59

2 Answers 2


You can get duct that is rated for underground use. It's more expensive of course, usually stainless steel.

Your MUCH bigger problem with this idea however is that you are introducing a place for ground water to enter your basement. There is no good way to seal something as large and flimsy as vent pipe penetrating a basement cinder block wall. This will result in a long term nightmare that will be very difficult and expensive to fix. The only possibility I can think of is to use cast iron pipe, like a sewer pipe, with an approved wall penetration method and all joints sealed against water leaking IN to the pipe and thereby into your basement. Making your dryer vent connect to the cast iron pipe may be a challenge, but creativity should win out.

But rather than that, I would call a "concrete coring company" as ask about them coring a hole for you in the stone wall. It's done all the time.

  • This makes sense. I don't know if I want to bore through the stone though, because I don't know how much space is between the upstairs stone and the interior plaster wall. This is a tricky one all around.
    – Mark
    Commented Apr 24, 2019 at 20:39
  • @jraefield Do you know if there is a sturdier type of vent pipe that will both connect to the rest of the piping, and also be strong enough to seal to the cinder block?
    – Mark
    Commented Apr 24, 2019 at 20:59
  • Not that I know of, that's why I suggested cast iron sewer pipe. When you penetrate the cinder block wall, you need a really tight seal around the pipe and against the edges of the hole. This is done with an expanding seal mechanism, so it puts a lot of pressure on the pipe. Nothing made of sheet metal is going to withstand that. Plastic pipe would, but that would not work for a dryer vent.
    – JRaef
    Commented Apr 24, 2019 at 22:14
  • I didn't even finish reading. Below grade? gtfouta here. +1
    – Mazura
    Commented Apr 25, 2019 at 2:01
  • @Mazura A penny for your thoughts, haha?!
    – Mark
    Commented Apr 25, 2019 at 2:29

You can do what you are suggesting. I like the bore through the stone better though.

If you want your method I'd use a plastic pipe as a sleeve or a corrugated metal, parge/concrete around the sleeve, run your underground rated sheet metal through the sleeve, parge/caulk between the sleeve and your sheet metal (you might want a fire rated caulk), then depending on your foundation wall you might want to use a fiber tape meant for foundation cracks, embed it with a foundation coating and put it around your sleeve/sheet metal penetration, further you could put a dimple board and blue skin the dimpleboard back to the sheet metal. Backfill after that. I am not sure what kind of cap to use once you penetrate the surface though.

I did something similar for air input as an earth tube but I used hdpe pipe 6" ID. It is 8' underground, comes through my poured foundation, is blue skinned and dimpled boarded on the outside. No water comes in.

A lot of work though so I'd go with coring the stone as a first pass.

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