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I am about to install a Dryer by mounting it on the wall in an inverted fashion, and then venting it through an existing dryer vent setup that has been designed with a duct joint that goes into the ceiling, and then there is a pipe that leads out of the roof to a roof vent. The two aren't connected, so that means air from the dryer would also circulate around the attic for a bit before finding it's way into the pipe leading to the roof vent.

From reading it seems that this would be bad practice and a potential fire hazard. There is insulation and other roof materials in there that would get exposed to this air.

My goal is to link the aluminium duct (semi-rigid) that I am going to buy directly to the pipe leading to the roof vent. However the way the roof is designed I can't get access to this well enough to attach it properly using a worm ring or metal duct tape.

The current setup looks nice, and I assume was used before with a dryer, I would like to know the risk of letting the air circulate somewhat in the roof area that is vented to the outside (but not sealed).

Or would anyone have any ideas on how I could attach the ducting directly to the pipe leading to the roof vent, thus eliminating any contact with the roof materials/insulation at all.

Ceiling - duct joint that leads to the roof cavity Ceiling - duct joint that leads to the roof cavity

Inside of duct joint, and pipe to roof vent you can see about 5 cm away Inside of duct joint, and pipe to roof vent you can see about 5 cm away

insulation in flat roof insulation in flat roof

pipe leading to roof vent pipe leading to roof vent

space under pipe leading to outside of roof space under pipe leading to outside of roof

Roof vent cap Dryer roof vent cap

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    Attic full of warm moist air -> mold heaven ...
    – brhans
    May 19 at 11:23
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    Two points: 1) Excellent close up pics! Unfortunately, they're so close up it's hard to tell what we're looking at. An over view pic or two of different areas with labels identifying where each of the details came from would help immeasurably. 2) "I am about to install a Dryer by mounting it on the wall in an inverted fashion," you're mounting a dryer upside down on the wall? I don't that that sentence says what you meant to say...
    – FreeMan
    May 19 at 11:43
  • Check if your dryer will support that exhaust stack height. If not it will become packed with lint.
    – Gil
    May 19 at 15:35
  • Thank you for the feedback on the description of my post, agree it is a bit unclear and confusing. The exhaust stack height is within the prescribed limits (under 2m) . I think I am going with point 3 below and going to cut out some of the drywall so I have access to the actual duct/vent that goes out of the roof. This should be the best solution with no air getting into the attic area.
    – Chris T
    May 20 at 11:07

1 Answer 1

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Long story short, you're going to want to figure out a way of connecting the ducting from the dryer to the ducting through the roof.

If you don't, you're going to end up with warm, moist air feeding mold growth in your attic, and you're going to end up with an attic full of lint, which is a fire hazard.

The vent through the roof is simply acting as a roof vent similar to the other roof vents you've got. It will do nothing special to vent your dryer until it's directly connected.


I see a couple of options for you:

  1. Noting just how close those are (you indicate 5cm), a piece of flex duct will probably be your only option to use this as is. You're just going to have to figure out how to get into this area of the attic and get the ducts connected.

    • It may be possible to place two large hose clamps around your flex duct then put the flex in position and slide the clamps down around the solid ends and tighten with a screwdriver bit in a powered driver (much easier to operate one-handed in a cramped environment).
    • Even better than a Phillips driver bit would be the appropriate sized nut driver - it will hold on better and be easier to keep connected. (Note: every hose clamp/jubilee clip I have seen has a combination Phillips/hex head where either type of driver will work. YMMV.)
  2. Have you checked up on the roof? Is it possible that you may be able to push the metal duct down from above to make it line up with the plastic fitting on the ceiling.

    • If so, a self-tapping sheet metal screw through the metal and into the plastic should hold it in place, or a hose clamp around the outside.
    • If you can't get it to line up perfectly, getting it "close enough" then sealing any remaining gap with duct tape might have to do. You'll get some lint stuck to the sticky inside of the tape, but once it's thoroughly covered, the rest of the lint should blow on past reasonably smoothly.
  3. If neither of these are workable, you may just have to bite the bullet and tear into the wall/ceiling to relocate the duct collar inside the house so that you can connect the duct work in the attic. The connection inside the laundry room is the easy one by comparison.

    • While this may seem to be a pain, repairing/patching drywall isn't a totally horrible experience and may be easier than squeezing into a rough/tight space in the attic. Plus, you'll learn how to repair drywall and will have a new skill for the next project you need to tackle.
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    I've been told to remove any such sheet metal screws, as their tips collect lint inside the duct. Instead, I've been told to just rely on exterior hose clamps and/or the good metal duct tape to both seal and mechanically secure connections. I'm not an expert, so am not sure if this is right.
    – Armand
    May 19 at 12:02
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    @Armand that sounds logical and may be the case. In any case, they'd collect less lint than flex duct would. I'm not an expert either, but I'm reasonably decent at figuring out workable (if not ideal) solutions...
    – FreeMan
    May 19 at 12:04
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    Check if your dryer will support that exhaust stack height. If not it will become packed with line.
    – Gil
    May 19 at 15:07
  • Good point, @Gil. You may want to put that on the main question to ensure the OP sees it. He won't be notified of the comment down here.
    – FreeMan
    May 19 at 15:08
  • Thank you @FreeMan for the detailed overview. and I've just seen these comments so understand the exhaust stack height concern. My spec dryer states that the "The vent system should be a maximum of 2 meters long with no more than 3 90 degree bends" - In the planned installation, the length of the complete system(from Dryer vent exhaust to top of the roof vent) is approximately: 1.2 meters. (Finding it's handy to have 1 meter wooden rulers around to measure this by poking it up through the duct until it hits the cap of the roof vent)
    – Chris T
    May 20 at 1:57

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